kernel.git
2 years agoKVM: x86: nSVM: implement nested vGIF
Maxim Levitsky [Tue, 22 Mar 2022 17:40:48 +0000 (19:40 +0200)]
KVM: x86: nSVM: implement nested vGIF

In case L1 enables vGIF for L2, the L2 cannot affect L1's GIF, regardless
of STGI/CLGI intercepts, and since VM entry enables GIF, this means
that L1's GIF is always 1 while L2 is running.

Thus in this case leave L1's vGIF in vmcb01, while letting L2
control the vGIF thus implementing nested vGIF.

Also allow KVM to toggle L1's GIF during nested entry/exit
by always using vmcb01.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322174050.241850-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: nSVM: support PAUSE filtering when L0 doesn't intercept PAUSE
Maxim Levitsky [Tue, 22 Mar 2022 17:40:47 +0000 (19:40 +0200)]
KVM: x86: nSVM: support PAUSE filtering when L0 doesn't intercept PAUSE

Expose the pause filtering and threshold in the guest CPUID
and support PAUSE filtering when possible:

- If the L0 doesn't intercept PAUSE (cpu_pm=on), then allow L1 to
  have full control over PAUSE filtering.

- if the L1 doesn't intercept PAUSE, use host values and update
  the adaptive count/threshold even when running nested.

- Otherwise always exit to L1; it is not really possible to merge
  the fields correctly.  It is expected that in this case, userspace
  will not enable this feature in the guest CPUID, to avoid having the
  guest update both fields pointlessly.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322174050.241850-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: nSVM: implement nested LBR virtualization
Maxim Levitsky [Tue, 22 Mar 2022 17:40:46 +0000 (19:40 +0200)]
KVM: x86: nSVM: implement nested LBR virtualization

This was tested with kvm-unit-test that was developed
for this purpose.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322174050.241850-3-mlevitsk@redhat.com>
[Copy all of DEBUGCTL except for reserved bits. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: nSVM: correctly virtualize LBR msrs when L2 is running
Maxim Levitsky [Tue, 22 Mar 2022 17:40:45 +0000 (19:40 +0200)]
KVM: x86: nSVM: correctly virtualize LBR msrs when L2 is running

When L2 is running without LBR virtualization, we should ensure
that L1's LBR msrs continue to update as usual.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322174050.241850-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: SVM: remove vgif_enabled()
Maxim Levitsky [Tue, 22 Mar 2022 17:24:49 +0000 (19:24 +0200)]
KVM: x86: SVM: remove vgif_enabled()

KVM always uses vgif when allowed, thus there is
no need to query current vmcb for it

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-9-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agokvm: x86: SVM: use vmcb* instead of svm->vmcb where it makes sense
Maxim Levitsky [Tue, 22 Mar 2022 17:24:44 +0000 (19:24 +0200)]
kvm: x86: SVM: use vmcb* instead of svm->vmcb where it makes sense

This makes the code a bit shorter and cleaner.

No functional change intended.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: SVM: use vmcb01 in init_vmcb
Maxim Levitsky [Tue, 22 Mar 2022 17:24:43 +0000 (18:24 +0100)]
KVM: x86: SVM: use vmcb01 in init_vmcb

Clarify that this function is not used to initialize any part of
the vmcb02.  No functional change intended.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Support the vCPU preemption check with nopvspin and realtime hint
Li RongQing [Wed, 9 Mar 2022 08:46:50 +0000 (16:46 +0800)]
KVM: x86: Support the vCPU preemption check with nopvspin and realtime hint

If guest kernel is configured with nopvspin, or CONFIG_PARAVIRT_SPINLOCK
is disabled, or guest find its has dedicated pCPUs from realtime hint
feature, the pvspinlock will be disabled, and vCPU preemption check
is disabled too.

Hoever, KVM still can emulating HLT for vCPU for both cases.  Checking if a vCPU
is preempted or not can still boost performance in IPI-heavy scenarios such as
unixbench file copy and pipe-based context switching tests:  Here the vCPU is
running with a dedicated pCPU, so the guest kernel has nopvspin but is
emulating HLT for the vCPU:

Testcase                                  Base    with patch
System Benchmarks Index Values            INDEX     INDEX
Dhrystone 2 using register variables     3278.4    3277.7
Double-Precision Whetstone                822.8     825.8
Execl Throughput                         1296.5     941.1
File Copy 1024 bufsize 2000 maxblocks    2124.2    2142.7
File Copy 256 bufsize 500 maxblocks      1335.9    1353.6
File Copy 4096 bufsize 8000 maxblocks    4256.3    4760.3
Pipe Throughput                          1050.1    1054.0
Pipe-based Context Switching              243.3     352.0
Process Creation                          820.1     814.4
Shell Scripts (1 concurrent)             2169.0    2086.0
Shell Scripts (8 concurrent)             7710.3    7576.3
System Call Overhead                      672.4     673.9
                                      ========    =======
System Benchmarks Index Score             1467.2   1483.0

Move the setting of pv_ops.lock.vcpu_is_preempted to kvm_guest_init, so
that it does not depend on pvspinlock.

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1646815610-43315-1-git-send-email-lirongqing@baidu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Test case for TSC scaling and offset sync
David Woodhouse [Fri, 25 Feb 2022 14:53:04 +0000 (14:53 +0000)]
KVM: x86: Test case for TSC scaling and offset sync

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220225145304.36166-4-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Don't snapshot "max" TSC if host TSC is constant
Sean Christopherson [Fri, 25 Feb 2022 14:53:03 +0000 (14:53 +0000)]
KVM: x86: Don't snapshot "max" TSC if host TSC is constant

Don't snapshot tsc_khz into max_tsc_khz during KVM initialization if the
host TSC is constant, in which case the actual TSC frequency will never
change and thus capturing the "max" TSC during initialization is
unnecessary, KVM can simply use tsc_khz during VM creation.

On CPUs with constant TSC, but not a hardware-specified TSC frequency,
snapshotting max_tsc_khz and using that to set a VM's default TSC
frequency can lead to KVM thinking it needs to manually scale the guest's
TSC if refining the TSC completes after KVM snapshots tsc_khz.  The
actual frequency never changes, only the kernel's calculation of what
that frequency is changes.  On systems without hardware TSC scaling, this
either puts KVM into "always catchup" mode (extremely inefficient), or
prevents creating VMs altogether.

Ideally, KVM would not be able to race with TSC refinement, or would have
a hook into tsc_refine_calibration_work() to get an alert when refinement
is complete.  Avoiding the race altogether isn't practical as refinement
takes a relative eternity; it's deliberately put on a work queue outside
of the normal boot sequence to avoid unnecessarily delaying boot.

Adding a hook is doable, but somewhat gross due to KVM's ability to be
built as a module.  And if the TSC is constant, which is likely the case
for every VMX/SVM-capable CPU produced in the last decade, the race can
be hit if and only if userspace is able to create a VM before TSC
refinement completes; refinement is slow, but not that slow.

For now, punt on a proper fix, as not taking a snapshot can help some
uses cases and not taking a snapshot is arguably correct irrespective of
the race with refinement.

[ dwmw2: Rebase on top of KVM-wide default_tsc_khz to ensure that all
         vCPUs get the same frequency even if we hit the race. ]

Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Anton Romanov <romanton@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220225145304.36166-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Accept KVM_[GS]ET_TSC_KHZ as a VM ioctl.
David Woodhouse [Fri, 25 Feb 2022 14:53:02 +0000 (14:53 +0000)]
KVM: x86: Accept KVM_[GS]ET_TSC_KHZ as a VM ioctl.

This sets the default TSC frequency for subsequently created vCPUs.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220225145304.36166-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/i8259: Remove a dead store of irq in a conditional block
Like Xu [Tue, 1 Mar 2022 12:02:17 +0000 (20:02 +0800)]
KVM: x86/i8259: Remove a dead store of irq in a conditional block

The [clang-analyzer-deadcode.DeadStores] helper reports
that the value stored to 'irq' is never read.

Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220301120217.38092-1-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: VMX: Prepare VMCS setting for posted interrupt enabling when APICv is available
Zeng Guang [Tue, 15 Mar 2022 14:58:36 +0000 (22:58 +0800)]
KVM: VMX: Prepare VMCS setting for posted interrupt enabling when APICv is available

Currently KVM setup posted interrupt VMCS only depending on
per-vcpu APICv activation status at the vCPU creation time.
However, this status can be toggled dynamically under some
circumstance. So potentially, later posted interrupt enabling
may be problematic without VMCS readiness.

To fix this, always settle the VMCS setting for posted interrupt
as long as APICv is available and lapic locates in kernel.

Signed-off-by: Zeng Guang <guang.zeng@intel.com>
Message-Id: <20220315145836.9910-1-guang.zeng@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Update self test for Xen PV timers
David Woodhouse [Wed, 9 Mar 2022 14:38:35 +0000 (14:38 +0000)]
KVM: x86/xen: Update self test for Xen PV timers

Add test cases for timers in the past, and reading the status of a timer
which has already fired.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220309143835.253911-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Add self tests for KVM_XEN_HVM_CONFIG_EVTCHN_SEND
David Woodhouse [Thu, 3 Mar 2022 15:41:27 +0000 (15:41 +0000)]
KVM: x86/xen: Add self tests for KVM_XEN_HVM_CONFIG_EVTCHN_SEND

Test a combination of event channel send, poll and timer operations.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220303154127.202856-18-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: handle PV spinlocks slowpath
Boris Ostrovsky [Thu, 3 Mar 2022 15:41:26 +0000 (15:41 +0000)]
KVM: x86/xen: handle PV spinlocks slowpath

Add support for SCHEDOP_poll hypercall.

This implementation is optimized for polling for a single channel, which
is what Linux does. Polling for multiple channels is not especially
efficient (and has not been tested).

PV spinlocks slow path uses this hypercall, and explicitly crash if it's
not supported.

[ dwmw2: Rework to use kvm_vcpu_halt(), not supported for 32-bit guests ]

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-17-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Advertise and document KVM_XEN_HVM_CONFIG_EVTCHN_SEND
David Woodhouse [Thu, 3 Mar 2022 15:41:25 +0000 (15:41 +0000)]
KVM: x86/xen: Advertise and document KVM_XEN_HVM_CONFIG_EVTCHN_SEND

At the end of the patch series adding this batch of event channel
acceleration features, finally add the feature bit which advertises
them and document it all.

For SCHEDOP_poll we need to wake a polling vCPU when a given port
is triggered, even when it's masked — and we want to implement that
in the kernel, for efficiency. So we want the kernel to know that it
has sole ownership of event channel delivery. Thus, we allow
userspace to make the 'promise' by setting the corresponding feature
bit in its KVM_XEN_HVM_CONFIG call. As we implement SCHEDOP_poll
bypass later, we will do so only if that promise has been made by
userspace.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-16-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Support per-vCPU event channel upcall via local APIC
David Woodhouse [Thu, 3 Mar 2022 15:41:24 +0000 (15:41 +0000)]
KVM: x86/xen: Support per-vCPU event channel upcall via local APIC

Windows uses a per-vCPU vector, and it's delivered via the local APIC
basically like an MSI (with associated EOI) unlike the traditional
guest-wide vector which is just magically asserted by Xen (and in the
KVM case by kvm_xen_has_interrupt() / kvm_cpu_get_extint()).

Now that the kernel is able to raise event channel events for itself,
being able to do so for Windows guests is also going to be useful.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-15-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Kernel acceleration for XENVER_version
David Woodhouse [Thu, 3 Mar 2022 15:41:23 +0000 (15:41 +0000)]
KVM: x86/xen: Kernel acceleration for XENVER_version

Turns out this is a fast path for PV guests because they use it to
trigger the event channel upcall. So letting it bounce all the way up
to userspace is not great.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-14-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: handle PV timers oneshot mode
Joao Martins [Thu, 3 Mar 2022 15:41:22 +0000 (15:41 +0000)]
KVM: x86/xen: handle PV timers oneshot mode

If the guest has offloaded the timer virq, handle the following
hypercalls for programming the timer:

    VCPUOP_set_singleshot_timer
    VCPUOP_stop_singleshot_timer
    set_timer_op(timestamp_ns)

The event channel corresponding to the timer virq is then used to inject
events once timer deadlines are met. For now we back the PV timer with
hrtimer.

[ dwmw2: Add save/restore, 32-bit compat mode, immediate delivery,
         don't check timer in kvm_vcpu_has_event() ]

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-13-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Add KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID
David Woodhouse [Thu, 3 Mar 2022 15:41:21 +0000 (15:41 +0000)]
KVM: x86/xen: Add KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID

In order to intercept hypercalls such as VCPUOP_set_singleshot_timer, we
need to be aware of the Xen CPU numbering.

This looks a lot like the Hyper-V handling of vpidx, for obvious reasons.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-12-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: handle PV IPI vcpu yield
Joao Martins [Thu, 3 Mar 2022 15:41:20 +0000 (15:41 +0000)]
KVM: x86/xen: handle PV IPI vcpu yield

Cooperative Linux guests after an IPI-many may yield vcpu if
any of the IPI'd vcpus were preempted (i.e. runstate is 'runnable'.)
Support SCHEDOP_yield for handling yield.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-11-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: intercept EVTCHNOP_send from guests
Joao Martins [Thu, 3 Mar 2022 15:41:19 +0000 (15:41 +0000)]
KVM: x86/xen: intercept EVTCHNOP_send from guests

Userspace registers a sending @port to either deliver to an @eventfd
or directly back to a local event channel port.

After binding events the guest or host may wish to bind those
events to a particular vcpu. This is usually done for unbound
and and interdomain events. Update requests are handled via the
KVM_XEN_EVTCHN_UPDATE flag.

Unregistered ports are handled by the emulator.

Co-developed-by: Ankur Arora <ankur.a.arora@oracle.com>
Co-developed-By: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-10-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Support direct injection of event channel events
David Woodhouse [Thu, 3 Mar 2022 15:41:18 +0000 (15:41 +0000)]
KVM: x86/xen: Support direct injection of event channel events

This adds a KVM_XEN_HVM_EVTCHN_SEND ioctl which allows direct injection
of events given an explicit { vcpu, port, priority } in precisely the
same form that those fields are given in the IRQ routing table.

Userspace is currently able to inject 2-level events purely by setting
the bits in the shared_info and vcpu_info, but FIFO event channels are
harder to deal with; we will need the kernel to take sole ownership of
delivery when we support those.

A patch advertising this feature with a new bit in the KVM_CAP_XEN_HVM
ioctl will be added in a subsequent patch.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-9-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Make kvm_xen_set_evtchn() reusable from other places
David Woodhouse [Thu, 3 Mar 2022 15:41:17 +0000 (15:41 +0000)]
KVM: x86/xen: Make kvm_xen_set_evtchn() reusable from other places

Clean it up to return -errno on error consistently, while still being
compatible with the return conventions for kvm_arch_set_irq_inatomic()
and the kvm_set_irq() callback.

We use -ENOTCONN to indicate when the port is masked. No existing users
care, except that it's negative.

Also allow it to optimise the vCPU lookup. Unless we abuse the lapic
map, there is no quick lookup from APIC ID to a vCPU; the logic in
kvm_get_vcpu_by_id() will just iterate over all vCPUs till it finds
the one it wants. So do that just once and stash the result in the
struct kvm_xen_evtchn for next time.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-8-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Use gfn_to_pfn_cache for vcpu_time_info
David Woodhouse [Thu, 3 Mar 2022 15:41:16 +0000 (15:41 +0000)]
KVM: x86/xen: Use gfn_to_pfn_cache for vcpu_time_info

This switches the final pvclock to kvm_setup_pvclock_pfncache() and now
the old kvm_setup_pvclock_page() can be removed.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-7-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Use gfn_to_pfn_cache for vcpu_info
David Woodhouse [Thu, 3 Mar 2022 15:41:15 +0000 (15:41 +0000)]
KVM: x86/xen: Use gfn_to_pfn_cache for vcpu_info

Currently, the fast path of kvm_xen_set_evtchn_fast() doesn't set the
index bits in the target vCPU's evtchn_pending_sel, because it only has
a userspace virtual address with which to do so. It just sets them in
the kernel, and kvm_xen_has_interrupt() then completes the delivery to
the actual vcpu_info structure when the vCPU runs.

Using a gfn_to_pfn_cache allows kvm_xen_set_evtchn_fast() to do the full
delivery in the common case.

Clean up the fallback case too, by moving the deferred delivery out into
a separate kvm_xen_inject_pending_events() function which isn't ever
called in atomic contexts as __kvm_xen_has_interrupt() is.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-6-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Use gfn_to_pfn_cache for pv_time
David Woodhouse [Thu, 3 Mar 2022 15:41:14 +0000 (15:41 +0000)]
KVM: x86: Use gfn_to_pfn_cache for pv_time

Add a new kvm_setup_guest_pvclock() which parallels the existing
kvm_setup_pvclock_page(). The latter will be removed once we convert
all users to the gfn_to_pfn_cache version.

Using the new cache, we can potentially let kvm_set_guest_paused() set
the PVCLOCK_GUEST_STOPPED bit directly rather than having to delegate
to the vCPU via KVM_REQ_CLOCK_UPDATE. But not yet.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-5-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/xen: Use gfn_to_pfn_cache for runstate area
David Woodhouse [Thu, 3 Mar 2022 15:41:13 +0000 (15:41 +0000)]
KVM: x86/xen: Use gfn_to_pfn_cache for runstate area

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-4-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: mark synthetic SMM vmexit as SVM_EXIT_SW
Maxim Levitsky [Tue, 1 Mar 2022 13:55:23 +0000 (15:55 +0200)]
KVM: x86: mark synthetic SMM vmexit as SVM_EXIT_SW

Use a dummy unused vmexit reason to mark the 'VM exit' that is happening
when kvm exits to handle SMM, which is not a real VM exit.

This makes it a bit easier to read the KVM trace, and avoids
other potential problems due to a stale vmexit reason in the vmcb.
If SVM_EXIT_SW somehow reaches svm_invoke_exit_handler(), instead,
svm_check_exit_valid() will return false and a WARN will be logged.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220301135526.136554-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: SVM: allow to force AVIC to be enabled
Maxim Levitsky [Tue, 1 Mar 2022 14:36:49 +0000 (16:36 +0200)]
KVM: x86: SVM: allow to force AVIC to be enabled

Apparently on some systems AVIC is disabled in CPUID but still usable.

Allow the user to override the CPUID if the user is willing to
take the risk.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220301143650.143749-7-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: nSVM: implement nested VMLOAD/VMSAVE
Maxim Levitsky [Tue, 1 Mar 2022 14:36:46 +0000 (16:36 +0200)]
KVM: x86: nSVM: implement nested VMLOAD/VMSAVE

This was tested by booting L1,L2,L3 (all Linux) and checking
that no VMLOAD/VMSAVE vmexits happened.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220301143650.143749-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoselftests: KVM: Test KVM_X86_QUIRK_FIX_HYPERCALL_INSN
Oliver Upton [Wed, 16 Mar 2022 00:55:38 +0000 (00:55 +0000)]
selftests: KVM: Test KVM_X86_QUIRK_FIX_HYPERCALL_INSN

Add a test that asserts KVM rewrites guest hypercall instructions to
match the running architecture (VMCALL on VMX, VMMCALL on SVM).
Additionally, test that with the quirk disabled, KVM no longer rewrites
guest instructions and instead injects a #UD.

Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220316005538.2282772-3-oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Allow userspace to opt out of hypercall patching
Oliver Upton [Wed, 16 Mar 2022 00:55:37 +0000 (00:55 +0000)]
KVM: x86: Allow userspace to opt out of hypercall patching

KVM handles the VMCALL/VMMCALL instructions very strangely. Even though
both of these instructions really should #UD when executed on the wrong
vendor's hardware (i.e. VMCALL on SVM, VMMCALL on VMX), KVM replaces the
guest's instruction with the appropriate instruction for the vendor.
Nonetheless, older guest kernels without commit 7f9e1d9e973e ("x86: kvm:
use alternatives for VMCALL vs. VMMCALL if kernel text is read-only")
do not patch in the appropriate instruction using alternatives, likely
motivating KVM's intervention.

Add a quirk allowing userspace to opt out of hypercall patching. If the
quirk is disabled, KVM synthesizes a #UD in the guest.

Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220316005538.2282772-2-oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: fix sending PV IPI
Li RongQing [Wed, 9 Mar 2022 08:35:44 +0000 (16:35 +0800)]
KVM: x86: fix sending PV IPI

If apic_id is less than min, and (max - apic_id) is greater than
KVM_IPI_CLUSTER_SIZE, then the third check condition is satisfied but
the new apic_id does not fit the bitmask.  In this case __send_ipi_mask
should send the IPI.

This is mostly theoretical, but it can happen if the apic_ids on three
iterations of the loop are for example 1, KVM_IPI_CLUSTER_SIZE, 0.

Fixes: 3c7773d7663 ("KVM: X86: Implement PV IPIs in linux guest")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1646814944-51801-1-git-send-email-lirongqing@baidu.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/mmu: do compare-and-exchange of gPTE via the user address
Paolo Bonzini [Tue, 29 Mar 2022 16:56:24 +0000 (12:56 -0400)]
KVM: x86/mmu: do compare-and-exchange of gPTE via the user address

FNAME(cmpxchg_gpte) is an inefficient mess.  It is at least decent if it
can go through get_user_pages_fast(), but if it cannot then it tries to
use memremap(); that is not just terribly slow, it is also wrong because
it assumes that the VM_PFNMAP VMA is contiguous.

The right way to do it would be to do the same thing as
hva_to_pfn_remapped() does since commit a59d68b54670 ("KVM: MMU: try to
fix up page faults before giving up", 2016-07-05), using follow_pte()
and fixup_user_fault() to determine the correct address to use for
memremap().  To do this, one could for example extract hva_to_pfn()
for use outside virt/kvm/kvm_main.c.  But really there is no reason to
do that either, because there is already a perfectly valid address to
do the cmpxchg() on, only it is a userspace address.  That means doing
user_access_begin()/user_access_end() and writing the code in assembly
to handle exceptions correctly.  Worse, the guest PTE can be 8-byte
even on i686 so there is the extra complication of using cmpxchg8b to
account for.  But at least it is an efficient mess.

(Thanks to Linus for suggesting improvement on the inline assembly).

Reported-by: Qiuhao Li <qiuhao@sysec.org>
Reported-by: Gaoning Pan <pgn@zju.edu.cn>
Reported-by: Yongkang Jia <kangel@zju.edu.cn>
Reported-by: syzbot+6cde2282daa792c49ab8@syzkaller.appspotmail.com
Debugged-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Tested-by: Maxim Levitsky <mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Fixes: b89f9ae1559d ("X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Remove redundant vm_entry_controls_clearbit() call
Zhenzhong Duan [Fri, 11 Mar 2022 10:26:43 +0000 (18:26 +0800)]
KVM: x86: Remove redundant vm_entry_controls_clearbit() call

When emulating exit from long mode, EFER_LMA is cleared with
vmx_set_efer().  This will already unset the VM_ENTRY_IA32E_MODE control
bit as requested by SDM, so there is no need to unset VM_ENTRY_IA32E_MODE
again in exit_lmode() explicitly.  In case EFER isn't supported by
hardware, long mode isn't supported, so exit_lmode() cannot be reached.

Note that, thanks to the shadow controls mechanism, this change doesn't
eliminate vmread or vmwrite.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220311102643.807507-3-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: cleanup enter_rmode()
Zhenzhong Duan [Fri, 11 Mar 2022 10:26:42 +0000 (18:26 +0800)]
KVM: x86: cleanup enter_rmode()

vmx_set_efer() sets uret->data but, in fact if the value of uret->data
will be used vmx_setup_uret_msrs() will have rewritten it with the value
returned by update_transition_efer().  uret->data is consumed if and only
if uret->load_into_hardware is true, and vmx_setup_uret_msrs() takes care
of (a) updating uret->data before setting uret->load_into_hardware to true
(b) setting uret->load_into_hardware to false if uret->data isn't updated.

Opportunistically use "vmx" directly instead of redoing to_vmx().

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220311102643.807507-2-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: SVM: fix tsc scaling when the host doesn't support it
Maxim Levitsky [Tue, 22 Mar 2022 17:24:48 +0000 (19:24 +0200)]
KVM: x86: SVM: fix tsc scaling when the host doesn't support it

It was decided that when TSC scaling is not supported,
the virtual MSR_AMD64_TSC_RATIO should still have the default '1.0'
value.

However in this case kvm_max_tsc_scaling_ratio is not set,
which breaks various assumptions.

Fix this by always calculating kvm_max_tsc_scaling_ratio regardless of
host support.  For consistency, do the same for VMX.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-8-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agokvm: x86: SVM: remove unused defines
Maxim Levitsky [Tue, 22 Mar 2022 17:24:47 +0000 (19:24 +0200)]
kvm: x86: SVM: remove unused defines

Remove some unused #defines from svm.c

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-7-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: SVM: move tsc ratio definitions to svm.h
Maxim Levitsky [Tue, 22 Mar 2022 17:24:46 +0000 (19:24 +0200)]
KVM: x86: SVM: move tsc ratio definitions to svm.h

Another piece of SVM spec which should be in the header file

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-6-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: SVM: fix avic spec based definitions again
Maxim Levitsky [Tue, 22 Mar 2022 17:24:45 +0000 (19:24 +0200)]
KVM: x86: SVM: fix avic spec based definitions again

Due to wrong rebase, commit
b4c1e60675cf5 ("KVM: SVM: Allow AVIC support on system w/ physical APIC ID > 255")

moved avic spec #defines back to avic.c.

Move them back, and while at it extend AVIC_DOORBELL_PHYSICAL_ID_MASK to 12
bits as well (it will be used in nested avic)

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: MIPS: remove reference to trap&emulate virtualization
Paolo Bonzini [Sun, 13 Mar 2022 14:05:22 +0000 (15:05 +0100)]
KVM: MIPS: remove reference to trap&emulate virtualization

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220313140522.1307751-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: document limitations of MSR filtering
Paolo Bonzini [Tue, 15 Mar 2022 22:17:15 +0000 (18:17 -0400)]
KVM: x86: document limitations of MSR filtering

MSR filtering requires an exit to userspace that is hard to implement and
would be very slow in the case of nested VMX vmexit and vmentry MSR
accesses.  Document the limitation.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Only do MSR filtering when access MSR by rdmsr/wrmsr
Hou Wenlong [Mon, 7 Mar 2022 12:26:33 +0000 (20:26 +0800)]
KVM: x86: Only do MSR filtering when access MSR by rdmsr/wrmsr

If MSR access is rejected by MSR filtering,
kvm_set_msr()/kvm_get_msr() would return KVM_MSR_RET_FILTERED,
and the return value is only handled well for rdmsr/wrmsr.
However, some instruction emulation and state transition also
use kvm_set_msr()/kvm_get_msr() to do msr access but may trigger
some unexpected results if MSR access is rejected, E.g. RDPID
emulation would inject a #UD but RDPID wouldn't cause a exit
when RDPID is supported in hardware and ENABLE_RDTSCP is set.
And it would also cause failure when load MSR at nested entry/exit.
Since msr filtering is based on MSR bitmap, it is better to only
do MSR filtering for rdmsr/wrmsr.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <2b2774154f7532c96a6f04d71c82a8bec7d9e80b.1646655860.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/emulator: Emulate RDPID only if it is enabled in guest
Hou Wenlong [Wed, 2 Mar 2022 13:15:14 +0000 (21:15 +0800)]
KVM: x86/emulator: Emulate RDPID only if it is enabled in guest

When RDTSCP is supported but RDPID is not supported in host,
RDPID emulation is available. However, __kvm_get_msr() would
only fail when RDTSCP/RDPID both are disabled in guest, so
the emulator wouldn't inject a #UD when RDPID is disabled but
RDTSCP is enabled in guest.

Fixes: 809be93a1ef1 ("KVM: x86: emulate RDPID")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <1dfd46ae5b76d3ed87bde3154d51c64ea64c99c1.1646226788.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/pmu: Fix and isolate TSX-specific performance event logic
Like Xu [Wed, 9 Mar 2022 08:42:57 +0000 (16:42 +0800)]
KVM: x86/pmu: Fix and isolate TSX-specific performance event logic

HSW_IN_TX* bits are used in generic code which are not supported on
AMD. Worse, these bits overlap with AMD EventSelect[11:8] and hence
using HSW_IN_TX* bits unconditionally in generic code is resulting in
unintentional pmu behavior on AMD. For example, if EventSelect[11:8]
is 0x2, pmc_reprogram_counter() wrongly assumes that
HSW_IN_TX_CHECKPOINTED is set and thus forces sampling period to be 0.

Also per the SDM, both bits 32 and 33 "may only be set if the processor
supports HLE or RTM" and for "IN_TXCP (bit 33): this bit may only be set
for IA32_PERFEVTSEL2."

Opportunistically eliminate code redundancy, because if the HSW_IN_TX*
bit is set in pmc->eventsel, it is already set in attr.config.

Reported-by: Ravi Bangoria <ravi.bangoria@amd.com>
Reported-by: Jim Mattson <jmattson@google.com>
Fixes: bbe6638bf4f6 ("perf, kvm: Support the in_tx/in_tx_cp modifiers in KVM arch perfmon emulation v5")
Co-developed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220309084257.88931-1-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: mmu: trace kvm_mmu_set_spte after the new SPTE was set
Maxim Levitsky [Wed, 2 Mar 2022 10:24:57 +0000 (12:24 +0200)]
KVM: x86: mmu: trace kvm_mmu_set_spte after the new SPTE was set

It makes more sense to print new SPTE value than the
old value.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220302102457.588450-1-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/svm: Clear reserved bits written to PerfEvtSeln MSRs
Jim Mattson [Sat, 26 Feb 2022 23:41:31 +0000 (15:41 -0800)]
KVM: x86/svm: Clear reserved bits written to PerfEvtSeln MSRs

AMD EPYC CPUs never raise a #GP for a WRMSR to a PerfEvtSeln MSR. Some
reserved bits are cleared, and some are not. Specifically, on
Zen3/Milan, bits 19 and 42 are not cleared.

When emulating such a WRMSR, KVM should not synthesize a #GP,
regardless of which bits are set. However, undocumented bits should
not be passed through to the hardware MSR. So, rather than checking
for reserved bits and synthesizing a #GP, just clear the reserved
bits.

This may seem pedantic, but since KVM currently does not support the
"Host/Guest Only" bits (41:40), it is necessary to clear these bits
rather than synthesizing #GP, because some popular guests (e.g Linux)
will set the "Host Only" bit even on CPUs that don't support
EFER.SVME, and they don't expect a #GP.

For example,

root@Ubuntu1804:~# perf stat -e r26 -a sleep 1

 Performance counter stats for 'system wide':

                 0      r26

       1.001070977 seconds time elapsed

Feb 23 03:59:58 Ubuntu1804 kernel: [  405.379957] unchecked MSR access error: WRMSR to 0xc0010200 (tried to write 0x0000020000130026) at rIP: 0xffffffff9b276a28 (native_write_msr+0x8/0x30)
Feb 23 03:59:58 Ubuntu1804 kernel: [  405.379958] Call Trace:
Feb 23 03:59:58 Ubuntu1804 kernel: [  405.379963]  amd_pmu_disable_event+0x27/0x90

Fixes: c97977012838 ("KVM: x86/vPMU: Implement AMD vPMU code for KVM")
Reported-by: Lotus Fenn <lotusf@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Like Xu <likexu@tencent.com>
Reviewed-by: David Dunn <daviddunn@google.com>
Message-Id: <20220226234131.2167175-1-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Trace all APICv inhibit changes and capture overall status
Sean Christopherson [Fri, 11 Mar 2022 04:35:17 +0000 (04:35 +0000)]
KVM: x86: Trace all APICv inhibit changes and capture overall status

Trace all APICv inhibit changes instead of just those that result in
APICv being (un)inhibited, and log the current state.  Debugging why
APICv isn't working is frustrating as it's hard to see why APICv is still
inhibited, and logging only the first inhibition means unnecessary onion
peeling.

Opportunistically drop the export of the tracepoint, it is not and should
not be used by vendor code due to the need to serialize toggling via
apicv_update_lock.

Note, using the common flow means kvm_apicv_init() switched from atomic
to non-atomic bitwise operations.  The VM is unreachable at init, so
non-atomic is perfectly ok.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220311043517.17027-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Add wrappers for setting/clearing APICv inhibits
Sean Christopherson [Fri, 11 Mar 2022 04:35:16 +0000 (04:35 +0000)]
KVM: x86: Add wrappers for setting/clearing APICv inhibits

Add set/clear wrappers for toggling APICv inhibits to make the call sites
more readable, and opportunistically rename the inner helpers to align
with the new wrappers and to make them more readable as well.  Invert the
flag from "activate" to "set"; activate is painfully ambiguous as it's
not obvious if the inhibit is being activated, or if APICv is being
activated, in which case the inhibit is being deactivated.

For the functions that take @set, swap the order of the inhibit reason
and @set so that the call sites are visually similar to those that bounce
through the wrapper.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220311043517.17027-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Make APICv inhibit reasons an enum and cleanup naming
Sean Christopherson [Fri, 11 Mar 2022 04:35:15 +0000 (04:35 +0000)]
KVM: x86: Make APICv inhibit reasons an enum and cleanup naming

Use an enum for the APICv inhibit reasons, there is no meaning behind
their values and they most definitely are not "unsigned longs".  Rename
the various params to "reason" for consistency and clarity (inhibit may
be confused as a command, i.e. inhibit APICv, instead of the reason that
is getting toggled/checked).

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220311043517.17027-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: X86: Handle implicit supervisor access with SMAP
Lai Jiangshan [Fri, 11 Mar 2022 07:03:44 +0000 (15:03 +0800)]
KVM: X86: Handle implicit supervisor access with SMAP

There are two kinds of implicit supervisor access
implicit supervisor access when CPL = 3
implicit supervisor access when CPL < 3

Current permission_fault() handles only the first kind for SMAP.

But if the access is implicit when SMAP is on, data may not be read
nor write from any user-mode address regardless the current CPL.

So the second kind should be also supported.

The first kind can be detect via CPL and access mode: if it is
supervisor access and CPL = 3, it must be implicit supervisor access.

But it is not possible to detect the second kind without extra
information, so this patch adds an artificial PFERR_EXPLICIT_ACCESS
into @access. This extra information also works for the first kind, so
the logic is changed to use this information for both cases.

The value of PFERR_EXPLICIT_ACCESS is deliberately chosen to be bit 48
which is in the most significant 16 bits of u64 and less likely to be
forced to change due to future hardware uses it.

This patch removes the call to ->get_cpl() for access mode is determined
by @access.  Not only does it reduce a function call, but also remove
confusions when the permission is checked for nested TDP.  The nested
TDP shouldn't have SMAP checking nor even the L2's CPL have any bearing
on it.  The original code works just because it is always user walk for
NPT and SMAP fault is not set for EPT in update_permission_bitmask.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <20220311070346.45023-5-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: X86: Rename variable smap to not_smap in permission_fault()
Lai Jiangshan [Fri, 11 Mar 2022 07:03:43 +0000 (15:03 +0800)]
KVM: X86: Rename variable smap to not_smap in permission_fault()

Comments above the variable says the bit is set when SMAP is overridden
or the same meaning in update_permission_bitmask(): it is not subjected
to SMAP restriction.

Renaming it to reflect the negative implication and make the code better
readability.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <20220311070346.45023-4-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: X86: Fix comments in update_permission_bitmask
Lai Jiangshan [Fri, 11 Mar 2022 07:03:42 +0000 (15:03 +0800)]
KVM: X86: Fix comments in update_permission_bitmask

The commit 67fc7b2f1473 ("KVM: MMU: speedup update_permission_bitmask")
refactored the code of update_permission_bitmask() and change the
comments.  It added a condition into a list to match the new code,
so the number/order for conditions in the comments should be updated
too.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <20220311070346.45023-3-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: X86: Change the type of access u32 to u64
Lai Jiangshan [Fri, 11 Mar 2022 07:03:41 +0000 (15:03 +0800)]
KVM: X86: Change the type of access u32 to u64

Change the type of access u32 to u64 for FNAME(walk_addr) and
->gva_to_gpa().

The kinds of accesses are usually combinations of UWX, and VMX/SVM's
nested paging adds a new factor of access: is it an access for a guest
page table or for a final guest physical address.

And SMAP relies a factor for supervisor access: explicit or implicit.

So @access in FNAME(walk_addr) and ->gva_to_gpa() is better to include
all these information to do the walk.

Although @access(u32) has enough bits to encode all the kinds, this
patch extends it to u64:
o Extra bits will be in the higher 32 bits, so that we can
  easily obtain the traditional access mode (UWX) by converting
  it to u32.
o Reuse the value for the access kind defined by SVM's nested
  paging (PFERR_GUEST_FINAL_MASK and PFERR_GUEST_PAGE_MASK) as
  @error_code in kvm_handle_page_fault().

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <20220311070346.45023-2-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: Remove dirty handling from gfn_to_pfn_cache completely
David Woodhouse [Thu, 3 Mar 2022 15:41:12 +0000 (15:41 +0000)]
KVM: Remove dirty handling from gfn_to_pfn_cache completely

It isn't OK to cache the dirty status of a page in internal structures
for an indefinite period of time.

Any time a vCPU exits the run loop to userspace might be its last; the
VMM might do its final check of the dirty log, flush the last remaining
dirty pages to the destination and complete a live migration. If we
have internal 'dirty' state which doesn't get flushed until the vCPU
is finally destroyed on the source after migration is complete, then
we have lost data because that will escape the final copy.

This problem already exists with the use of kvm_vcpu_unmap() to mark
pages dirty in e.g. VMX nesting.

Note that the actual Linux MM already considers the page to be dirty
since we have a writeable mapping of it. This is just about the KVM
dirty logging.

For the nesting-style use cases (KVM_GUEST_USES_PFN) we will need to
track which gfn_to_pfn_caches have been used and explicitly mark the
corresponding pages dirty before returning to userspace. But we would
have needed external tracking of that anyway, rather than walking the
full list of GPCs to find those belonging to this vCPU which are dirty.

So let's rely *solely* on that external tracking, and keep it simple
rather than laying a tempting trap for callers to fall into.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: Use enum to track if cached PFN will be used in guest and/or host
Sean Christopherson [Thu, 3 Mar 2022 15:41:11 +0000 (15:41 +0000)]
KVM: Use enum to track if cached PFN will be used in guest and/or host

Replace the guest_uses_pa and kernel_map booleans in the PFN cache code
with a unified enum/bitmask. Using explicit names makes it easier to
review and audit call sites.

Opportunistically add a WARN to prevent passing garbage; instantating a
cache without declaring its usage is either buggy or pointless.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: SVM: Fix kvm_cache_regs.h inclusions for is_guest_mode()
Peter Gonda [Fri, 4 Mar 2022 16:10:32 +0000 (08:10 -0800)]
KVM: SVM: Fix kvm_cache_regs.h inclusions for is_guest_mode()

Include kvm_cache_regs.h to pick up the definition of is_guest_mode(),
which is referenced by nested_svm_virtualize_tpr() in svm.h. Remove
include from svm_onhpyerv.c which was done only because of lack of
include in svm.h.

Fixes: cf74f5b50cd6d ("KVM: SVM: Move Nested SVM Implementation to nested.c")
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Peter Gonda <pgonda@google.com>
Message-Id: <20220304161032.2270688-1-pgonda@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/pmu: Use different raw event masks for AMD and Intel
Jim Mattson [Tue, 8 Mar 2022 01:24:52 +0000 (17:24 -0800)]
KVM: x86/pmu: Use different raw event masks for AMD and Intel

The third nybble of AMD's event select overlaps with Intel's IN_TX and
IN_TXCP bits. Therefore, we can't use AMD64_RAW_EVENT_MASK on Intel
platforms that support TSX.

Declare a raw_event_mask in the kvm_pmu structure, initialize it in
the vendor-specific pmu_refresh() functions, and use that mask for
PERF_TYPE_RAW configurations in reprogram_gp_counter().

Fixes: 9d0055ac0e41 ("KVM: x86/pmu: Use AMD64_RAW_EVENT_MASK for PERF_TYPE_RAW")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220308012452.3468611-1-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: Don't actually set a request when evicting vCPUs for GFN cache invd
Sean Christopherson [Wed, 23 Feb 2022 16:53:02 +0000 (16:53 +0000)]
KVM: Don't actually set a request when evicting vCPUs for GFN cache invd

Don't actually set a request bit in vcpu->requests when making a request
purely to force a vCPU to exit the guest.  Logging a request but not
actually consuming it would cause the vCPU to get stuck in an infinite
loop during KVM_RUN because KVM would see the pending request and bail
from VM-Enter to service the request.

Note, it's currently impossible for KVM to set KVM_REQ_GPC_INVALIDATE as
nothing in KVM is wired up to set guest_uses_pa=true.  But, it'd be all
too easy for arch code to introduce use of kvm_gfn_to_pfn_cache_init()
without implementing handling of the request, especially since getting
test coverage of MMU notifier interaction with specific KVM features
usually requires a directed test.

Opportunistically rename gfn_to_pfn_cache_invalidate_start()'s wake_vcpus
to evict_vcpus.  The purpose of the request is to get vCPUs out of guest
mode, it's supposed to _avoid_ waking vCPUs that are blocking.

Opportunistically rename KVM_REQ_GPC_INVALIDATE to be more specific as to
what it wants to accomplish, and to genericize the name so that it can
used for similar but unrelated scenarios, should they arise in the future.
Add a comment and documentation to explain why the "no action" request
exists.

Add compile-time assertions to help detect improper usage.  Use the inner
assertless helper in the one s390 path that makes requests without a
hardcoded request.

Cc: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220223165302.3205276-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: avoid double put_page with gfn-to-pfn cache
David Woodhouse [Tue, 29 Mar 2022 17:11:47 +0000 (13:11 -0400)]
KVM: avoid double put_page with gfn-to-pfn cache

If the cache's user host virtual address becomes invalid, there
is still a path from kvm_gfn_to_pfn_cache_refresh() where __release_gpc()
could release the pfn but the gpc->pfn field has not been overwritten
with an error value.  If this happens, kvm_gfn_to_pfn_cache_unmap will
call put_page again on the same page.

Cc: stable@vger.kernel.org
Fixes: a6e521f19aee ("KVM: Reinstate gfn_to_pfn_cache with invalidation support")
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86/mmu: Zap only TDP MMU leafs in zap range and mmu_notifier unmap
Sean Christopherson [Fri, 25 Mar 2022 23:03:48 +0000 (23:03 +0000)]
KVM: x86/mmu: Zap only TDP MMU leafs in zap range and mmu_notifier unmap

Re-introduce zapping only leaf SPTEs in kvm_zap_gfn_range() and
kvm_tdp_mmu_unmap_gfn_range(), this time without losing a pending TLB
flush when processing multiple roots (including nested TDP shadow roots).
Dropping the TLB flush resulted in random crashes when running Hyper-V
Server 2019 in a guest with KSM enabled in the host (or any source of
mmu_notifier invalidations, KSM is just the easiest to force).

This effectively revert commits a57228559d9de5b1ace0b99fcef1713e9ccad601
and 6e1bd1e4895f394fb10aa97dc23cd035fdcd82cc, and thus restores commit
340052296c0b97853e8a0e1e60b76333fa033843, plus this delta on top:

bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, int as_id, gfn_t start, gfn_t end,
        struct kvm_mmu_page *root;

        for_each_tdp_mmu_root_yield_safe(kvm, root, as_id)
-               flush = tdp_mmu_zap_leafs(kvm, root, start, end, can_yield, false);
+               flush = tdp_mmu_zap_leafs(kvm, root, start, end, can_yield, flush);

        return flush;
 }

Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220325230348.2587437-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: SVM: fix panic on out-of-bounds guest IRQ
Yi Wang [Wed, 9 Mar 2022 11:30:25 +0000 (19:30 +0800)]
KVM: SVM: fix panic on out-of-bounds guest IRQ

As guest_irq is coming from KVM_IRQFD API call, it may trigger
crash in svm_update_pi_irte() due to out-of-bounds:

crash> bt
PID: 22218  TASK: ffff951a6ad74980  CPU: 73  COMMAND: "vcpu8"
 #0 [ffffb1ba6707fa40] machine_kexec at ffffffff8565b397
 #1 [ffffb1ba6707fa90] __crash_kexec at ffffffff85788a6d
 #2 [ffffb1ba6707fb58] crash_kexec at ffffffff8578995d
 #3 [ffffb1ba6707fb70] oops_end at ffffffff85623c0d
 #4 [ffffb1ba6707fb90] no_context at ffffffff856692c9
 #5 [ffffb1ba6707fbf8] exc_page_fault at ffffffff85f95b51
 #6 [ffffb1ba6707fc50] asm_exc_page_fault at ffffffff86000ace
    [exception RIP: svm_update_pi_irte+227]
    RIP: ffffffffc0761b53  RSP: ffffb1ba6707fd08  RFLAGS: 00010086
    RAX: ffffb1ba6707fd78  RBX: ffffb1ba66d91000  RCX: 0000000000000001
    RDX: 00003c803f63f1c0  RSI: 000000000000019a  RDI: ffffb1ba66db2ab8
    RBP: 000000000000019a   R8: 0000000000000040   R9: ffff94ca41b82200
    R10: ffffffffffffffcf  R11: 0000000000000001  R12: 0000000000000001
    R13: 0000000000000001  R14: ffffffffffffffcf  R15: 000000000000005f
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ffffb1ba6707fdb8] kvm_irq_routing_update at ffffffffc09f19a1 [kvm]
 #8 [ffffb1ba6707fde0] kvm_set_irq_routing at ffffffffc09f2133 [kvm]
 #9 [ffffb1ba6707fe18] kvm_vm_ioctl at ffffffffc09ef544 [kvm]
    RIP: 00007f143c36488b  RSP: 00007f143a4e04b8  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 00007f05780041d0  RCX: 00007f143c36488b
    RDX: 00007f05780041d0  RSI: 000000004008ae6a  RDI: 0000000000000020
    RBP: 00000000000004e8   R8: 0000000000000008   R9: 00007f05780041e0
    R10: 00007f0578004560  R11: 0000000000000246  R12: 00000000000004e0
    R13: 000000000000001a  R14: 00007f1424001c60  R15: 00007f0578003bc0
    ORIG_RAX: 0000000000000010  CS: 0033  SS: 002b

Vmx have been fix this in commit 7145f459eb74 (KVM: VMX: Do not BUG() on
out-of-bounds guest IRQ), so we can just copy source from that to fix
this.

Co-developed-by: Yi Liu <liu.yi24@zte.com.cn>
Signed-off-by: Yi Liu <liu.yi24@zte.com.cn>
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Message-Id: <20220309113025.44469-1-wang.yi59@zte.com.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: MMU: propagate alloc_workqueue failure
Paolo Bonzini [Fri, 25 Mar 2022 16:42:52 +0000 (12:42 -0400)]
KVM: MMU: propagate alloc_workqueue failure

If kvm->arch.tdp_mmu_zap_wq cannot be created, the failure has
to be propagated up to kvm_mmu_init_vm and kvm_arch_init_vm.
kvm_arch_init_vm also has to undo all the initialization, so
group all the MMU initialization code at the beginning and
handle cleaning up of kvm_page_track_init.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Forbid VMM to set SYNIC/STIMER MSRs when SynIC wasn't activated
Vitaly Kuznetsov [Fri, 25 Mar 2022 13:21:40 +0000 (14:21 +0100)]
KVM: x86: Forbid VMM to set SYNIC/STIMER MSRs when SynIC wasn't activated

Setting non-zero values to SYNIC/STIMER MSRs activates certain features,
this should not happen when KVM_CAP_HYPERV_SYNIC{,2} was not activated.

Note, it would've been better to forbid writing anything to SYNIC/STIMER
MSRs, including zeroes, however, at least QEMU tries clearing
HV_X64_MSR_STIMER0_CONFIG without SynIC. HV_X64_MSR_EOM MSR is somewhat
'special' as writing zero there triggers an action, this also should not
happen when SynIC wasn't activated.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220325132140.25650-4-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Avoid theoretical NULL pointer dereference in kvm_irq_delivery_to_apic_fast()
Vitaly Kuznetsov [Fri, 25 Mar 2022 13:21:39 +0000 (14:21 +0100)]
KVM: x86: Avoid theoretical NULL pointer dereference in kvm_irq_delivery_to_apic_fast()

When kvm_irq_delivery_to_apic_fast() is called with APIC_DEST_SELF
shorthand, 'src' must not be NULL. Crash the VM with KVM_BUG_ON()
instead of crashing the host.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220325132140.25650-3-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Check lapic_in_kernel() before attempting to set a SynIC irq
Vitaly Kuznetsov [Fri, 25 Mar 2022 13:21:38 +0000 (14:21 +0100)]
KVM: x86: Check lapic_in_kernel() before attempting to set a SynIC irq

When KVM_CAP_HYPERV_SYNIC{,2} is activated, KVM already checks for
irqchip_in_kernel() so normally SynIC irqs should never be set. It is,
however,  possible for a misbehaving VMM to write to SYNIC/STIMER MSRs
causing erroneous behavior.

The immediate issue being fixed is that kvm_irq_delivery_to_apic()
(kvm_irq_delivery_to_apic_fast()) crashes when called with
'irq.shorthand = APIC_DEST_SELF' and 'src == NULL'.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220325132140.25650-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoDocumentation: KVM: add API issues section
Paolo Bonzini [Tue, 22 Mar 2022 11:07:12 +0000 (12:07 +0100)]
Documentation: KVM: add API issues section

Add a section to document all the different ways in which the KVM API sucks.

I am sure there are way more, give people a place to vent so that userspace
authors are aware.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220322110712.222449-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoDocumentation: KVM: add virtual CPU errata documentation
Paolo Bonzini [Tue, 22 Mar 2022 11:07:11 +0000 (12:07 +0100)]
Documentation: KVM: add virtual CPU errata documentation

Add a file to document all the different ways in which the virtual CPU
emulation is imperfect.  Include an example to show how to document
such errata.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Message-Id: <20220322110712.222449-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoDocumentation: KVM: add separate directories for architecture-specific documentation
Paolo Bonzini [Tue, 22 Mar 2022 11:07:10 +0000 (12:07 +0100)]
Documentation: KVM: add separate directories for architecture-specific documentation

ARM already has an arm/ subdirectory, but s390 and x86 do not even though
they have a relatively large number of files specific to them.  Create
new directories in Documentation/virt/kvm for these two architectures
as well.

While at it, group the API documentation and the developer documentation
in the table of contents.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220322110712.222449-2-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoDocumentation: kvm: include new locks
Paolo Bonzini [Tue, 22 Mar 2022 11:07:20 +0000 (12:07 +0100)]
Documentation: kvm: include new locks

kvm->mn_invalidate_lock and kvm->slots_arch_lock were not included in the
documentation, add them.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220322110720.222499-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoDocumentation: kvm: fixes for locking.rst
Paolo Bonzini [Tue, 22 Mar 2022 11:07:19 +0000 (12:07 +0100)]
Documentation: kvm: fixes for locking.rst

Separate the various locks clearly, and include the new names of blocked_vcpu_on_cpu_lock
and blocked_vcpu_on_cpu.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220322110720.222499-2-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Fix clang -Wimplicit-fallthrough in do_host_cpuid()
Nathan Chancellor [Tue, 22 Mar 2022 15:29:06 +0000 (08:29 -0700)]
KVM: x86: Fix clang -Wimplicit-fallthrough in do_host_cpuid()

Clang warns:

  arch/x86/kvm/cpuid.c:739:2: error: unannotated fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
          default:
          ^
  arch/x86/kvm/cpuid.c:739:2: note: insert 'break;' to avoid fall-through
          default:
          ^
          break;
  1 error generated.

Clang is a little more pedantic than GCC, which does not warn when
falling through to a case that is just break or return. Clang's version
is more in line with the kernel's own stance in deprecated.rst, which
states that all switch/case blocks must end in either break,
fallthrough, continue, goto, or return. Add the missing break to silence
the warning.

Fixes: f7cb9809520f ("KVM: x86: synthesize CPUID leaf 0x80000021h if useful")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Message-Id: <20220322152906.112164-1-nathan@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoRevert "KVM: set owner of cpu and vm file operations"
David Matlack [Thu, 3 Mar 2022 18:33:28 +0000 (18:33 +0000)]
Revert "KVM: set owner of cpu and vm file operations"

This reverts commit 2c67e1ebd8d0ace1120955916f4c103ad066f8b6.

Now that the KVM module's lifetime is tied to kvm.users_count, there is
no need to also tie it's lifetime to the lifetime of the VM and vCPU
file descriptors.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220303183328.1499189-3-dmatlack@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: Prevent module exit until all VMs are freed
David Matlack [Thu, 3 Mar 2022 18:33:27 +0000 (18:33 +0000)]
KVM: Prevent module exit until all VMs are freed

Tie the lifetime the KVM module to the lifetime of each VM via
kvm.users_count. This way anything that grabs a reference to the VM via
kvm_get_kvm() cannot accidentally outlive the KVM module.

Prior to this commit, the lifetime of the KVM module was tied to the
lifetime of /dev/kvm file descriptors, VM file descriptors, and vCPU
file descriptors by their respective file_operations "owner" field.
This approach is insufficient because references grabbed via
kvm_get_kvm() do not prevent closing any of the aforementioned file
descriptors.

This fixes a long standing theoretical bug in KVM that at least affects
async page faults. kvm_setup_async_pf() grabs a reference via
kvm_get_kvm(), and drops it in an asynchronous work callback. Nothing
prevents the VM file descriptor from being closed and the KVM module
from being unloaded before this callback runs.

Fixes: 62cd8956f013 ("KVM: Halt vcpu if page it tries to access is swapped out")
Fixes: 2c67e1ebd8d0 ("KVM: set owner of cpu and vm file operations")
Cc: stable@vger.kernel.org
Suggested-by: Ben Gardon <bgardon@google.com>
[ Based on a patch from Ben implemented for Google's kernel. ]
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220303183328.1499189-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: use kvcalloc for array allocations
Paolo Bonzini [Tue, 8 Mar 2022 09:57:39 +0000 (04:57 -0500)]
KVM: use kvcalloc for array allocations

Instead of using array_size, use a function that takes care of the
multiplication.  While at it, switch to kvcalloc since this allocation
should not be very large.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2
Oliver Upton [Tue, 1 Mar 2022 06:03:47 +0000 (06:03 +0000)]
KVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2

KVM_CAP_DISABLE_QUIRKS is irrevocably broken. The capability does not
advertise the set of quirks which may be disabled to userspace, so it is
impossible to predict the behavior of KVM. Worse yet,
KVM_CAP_DISABLE_QUIRKS will tolerate any value for cap->args[0], meaning
it fails to reject attempts to set invalid quirk bits.

The only valid workaround for the quirky quirks API is to add a new CAP.
Actually advertise the set of quirks that can be disabled to userspace
so it can predict KVM's behavior. Reject values for cap->args[0] that
contain invalid bits.

Finally, add documentation for the new capability and describe the
existing quirks.

Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220301060351.442881-5-oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agokvm: x86: Require const tsc for RT
Thomas Gleixner [Sun, 6 Nov 2011 11:26:18 +0000 (12:26 +0100)]
kvm: x86: Require const tsc for RT

Non constant TSC is a nightmare on bare metal already, but with
virtualization it becomes a complete disaster because the workarounds
are horrible latency wise. That's also a preliminary for running RT in
a guest on top of a RT host.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Message-Id: <Yh5eJSG19S2sjZfy@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: synthesize CPUID leaf 0x80000021h if useful
Paolo Bonzini [Thu, 21 Oct 2021 21:19:27 +0000 (17:19 -0400)]
KVM: x86: synthesize CPUID leaf 0x80000021h if useful

Guests X86_BUG_NULL_SEG if and only if the host has them.  Use the info
from static_cpu_has_bug to form the 0x80000021 CPUID leaf that was
defined for Zen3.  Userspace can then set the bit even on older CPUs
that do not have the bug, such as Zen2.

Do the same for X86_FEATURE_LFENCE_RDTSC as well, since various processors
have had very different ways of detecting it and not all of them are
available to userspace.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: add support for CPUID leaf 0x80000021
Paolo Bonzini [Thu, 28 Oct 2021 17:26:38 +0000 (13:26 -0400)]
KVM: x86: add support for CPUID leaf 0x80000021

CPUID leaf 0x80000021 defines some features (or lack of bugs) of AMD
processors.  Expose the ones that make sense via KVM_GET_SUPPORTED_CPUID.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoKVM: x86: do not use KVM_X86_OP_OPTIONAL_RET0 for get_mt_mask
Maxim Levitsky [Fri, 18 Mar 2022 16:27:41 +0000 (12:27 -0400)]
KVM: x86: do not use KVM_X86_OP_OPTIONAL_RET0 for get_mt_mask

KVM_X86_OP_OPTIONAL_RET0 can only be used with 32-bit return values on 32-bit
systems, because unsigned long is only 32-bits wide there and 64-bit values
are returned in edx:eax.

Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoRevert "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()"
Paolo Bonzini [Fri, 18 Mar 2022 16:30:32 +0000 (12:30 -0400)]
Revert "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()"

This reverts commit 340052296c0b97853e8a0e1e60b76333fa033843.

Multi-vCPU Hyper-V guests started crashing randomly on boot with the
latest kvm/queue and the problem can be bisected the problem to this
particular patch. Basically, I'm not able to boot e.g. 16-vCPU guest
successfully anymore. Both Intel and AMD seem to be affected. Reverting
the commit saves the day.

Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agokvm: x86/mmu: Flush TLB before zap_gfn_range releases RCU
Paolo Bonzini [Mon, 21 Mar 2022 09:05:08 +0000 (05:05 -0400)]
kvm: x86/mmu: Flush TLB before zap_gfn_range releases RCU

Since "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()"
is going to be reverted, it's not going to be true anymore that
the zap-page flow does not free any 'struct kvm_mmu_page'.  Introduce
an early flush before tdp_mmu_zap_leafs() returns, to preserve
bisectability.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 years agoMerge tag 'kvmarm-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmar...
Paolo Bonzini [Fri, 18 Mar 2022 16:43:24 +0000 (12:43 -0400)]
Merge tag 'kvmarm-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for 5.18

- Proper emulation of the OSLock feature of the debug architecture

- Scalibility improvements for the MMU lock when dirty logging is on

- New VMID allocator, which will eventually help with SVA in VMs

- Better support for PMUs in heterogenous systems

- PSCI 1.1 support, enabling support for SYSTEM_RESET2

- Implement CONFIG_DEBUG_LIST at EL2

- Make CONFIG_ARM64_ERRATUM_2077057 default y

- Reduce the overhead of VM exit when no interrupt is pending

- Remove traces of 32bit ARM host support from the documentation

- Updated vgic selftests

- Various cleanups, doc updates and spelling fixes

2 years agoKVM: arm64: fix typos in comments
Julia Lawall [Fri, 18 Mar 2022 10:37:19 +0000 (11:37 +0100)]
KVM: arm64: fix typos in comments

Various spelling mistakes in comments.
Detected with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220318103729.157574-24-Julia.Lawall@inria.fr
2 years agoKVM: arm64: Generalise VM features into a set of flags
Marc Zyngier [Fri, 11 Mar 2022 17:39:47 +0000 (17:39 +0000)]
KVM: arm64: Generalise VM features into a set of flags

We currently deal with a set of booleans for VM features,
while they could be better represented as set of flags
contained in an unsigned long, similarily to what we are
doing on the CPU side.

Signed-off-by: Marc Zyngier <maz@kernel.org>
[Oliver: Flag-ify the 'ran_once' boolean]
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220311174001.605719-2-oupton@google.com
2 years agoMerge tag 'kvm-riscv-5.18-1' of https://github.com/kvm-riscv/linux into HEAD
Paolo Bonzini [Tue, 15 Mar 2022 21:20:25 +0000 (17:20 -0400)]
Merge tag 'kvm-riscv-5.18-1' of https://github.com/kvm-riscv/linux into HEAD

KVM/riscv changes for 5.18

- Prevent KVM_COMPAT from being selected
- Refine __kvm_riscv_switch_to() implementation
- RISC-V SBI v0.3 support

2 years agoMerge tag 'kvm-s390-next-5.18-2' of https://git.kernel.org/pub/scm/linux/kernel/git...
Paolo Bonzini [Tue, 15 Mar 2022 21:19:02 +0000 (17:19 -0400)]
Merge tag 'kvm-s390-next-5.18-2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fix, test and feature for 5.18 part 2

- memop selftest
- fix SCK locking
- adapter interruptions virtualization for secure guests

2 years agoKVM: s390: selftests: Add error memop tests
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:41 +0000 (13:58 +0100)]
KVM: s390: selftests: Add error memop tests

Test that errors occur if key protection disallows access, including
tests for storage and fetch protection override. Perform tests for both
logical vcpu and absolute vm ioctls.
Also extend the existing tests to the vm ioctl.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-6-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2 years agoKVM: s390: selftests: Add more copy memop tests
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:40 +0000 (13:58 +0100)]
KVM: s390: selftests: Add more copy memop tests

Do not just test the actual copy, but also that success is indicated
when using the check only flag.
Add copy test with storage key checking enabled, including tests for
storage and fetch protection override.
These test cover both logical vcpu ioctls as well as absolute vm ioctls.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-5-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2 years agoKVM: s390: selftests: Add named stages for memop test
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:39 +0000 (13:58 +0100)]
KVM: s390: selftests: Add named stages for memop test

The stages synchronize guest and host execution.
This helps the reader and constraits the execution of the test -- if the
observed staging differs from the expected the test fails.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-4-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2 years agoKVM: s390: selftests: Add macro as abstraction for MEM_OP
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:38 +0000 (13:58 +0100)]
KVM: s390: selftests: Add macro as abstraction for MEM_OP

In order to achieve good test coverage we need to be able to invoke the
MEM_OP ioctl with all possible parametrizations.
However, for a given test, we want to be concise and not specify a long
list of default values for parameters not relevant for the test, so the
readers attention is not needlessly diverted.
Add a macro that enables this and convert the existing test to use it.
The macro emulates named arguments and hides some of the ioctl's
redundancy, e.g. sets the key flag if an access key is specified.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-3-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2 years agoKVM: s390: selftests: Split memop tests
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:37 +0000 (13:58 +0100)]
KVM: s390: selftests: Split memop tests

Split success case/copy test from error test, making them independent.
This means they do not share state and are easier to understand.
Also, new test can be added in the same manner without affecting the old
ones. In order to make that simpler, introduce functionality for the
setup of commonly used variables.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-2-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2 years agoKVM: s390x: fix SCK locking
Claudio Imbrenda [Tue, 1 Mar 2022 14:33:40 +0000 (15:33 +0100)]
KVM: s390x: fix SCK locking

When handling the SCK instruction, the kvm lock is taken, even though
the vcpu lock is already being held. The normal locking order is kvm
lock first and then vcpu lock. This is can (and in some circumstances
does) lead to deadlocks.

The function kvm_s390_set_tod_clock is called both by the SCK handler
and by some IOCTLs to set the clock. The IOCTLs will not hold the vcpu
lock, so they can safely take the kvm lock. The SCK handler holds the
vcpu lock, but will also somehow need to acquire the kvm lock without
relinquishing the vcpu lock.

The solution is to factor out the code to set the clock, and provide
two wrappers. One is called like the original function and does the
locking, the other is called kvm_s390_try_set_tod_clock and uses
trylock to try to acquire the kvm lock. This new wrapper is then used
in the SCK handler. If locking fails, -EAGAIN is returned, which is
eventually propagated to userspace, thus also freeing the vcpu lock and
allowing for forward progress.

This is not the most efficient or elegant way to solve this issue, but
the SCK instruction is deprecated and its performance is not critical.

The goal of this patch is just to provide a simple but correct way to
fix the bug.

Fixes: 4fa1473a345b ("KVM: s390: Intercept SCK instruction")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220301143340.111129-1-imbrenda@linux.ibm.com
Cc: stable@vger.kernel.org
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2 years agoRISC-V: KVM: Implement SBI HSM suspend call
Anup Patel [Mon, 31 Jan 2022 07:01:36 +0000 (12:31 +0530)]
RISC-V: KVM: Implement SBI HSM suspend call

The SBI v0.3 specification extends SBI HSM extension by adding SBI HSM
suspend call and related HART states. This patch extends the KVM RISC-V
HSM implementation to provide KVM guest a minimal SBI HSM suspend call
which is equivalent to a WFI instruction.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
2 years agoRISC-V: KVM: Add common kvm_riscv_vcpu_wfi() function
Anup Patel [Mon, 31 Jan 2022 06:29:44 +0000 (11:59 +0530)]
RISC-V: KVM: Add common kvm_riscv_vcpu_wfi() function

The wait for interrupt (WFI) instruction emulation can share the VCPU
halt logic with SBI HSM suspend emulation so this patch adds a common
kvm_riscv_vcpu_wfi() function for this purpose.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
2 years agoRISC-V: Add SBI HSM suspend related defines
Anup Patel [Mon, 15 Feb 2021 05:13:39 +0000 (10:43 +0530)]
RISC-V: Add SBI HSM suspend related defines

We add defines related to SBI HSM suspend call and also update HSM states
naming as-per the latest SBI specification.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
2 years agoRISC-V: KVM: Implement SBI v0.3 SRST extension
Anup Patel [Mon, 31 Jan 2022 05:23:13 +0000 (10:53 +0530)]
RISC-V: KVM: Implement SBI v0.3 SRST extension

The SBI v0.3 specification defines SRST (System Reset) extension which
provides a standard poweroff and reboot interface. This patch implements
SRST extension for the KVM Guest.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
2 years agoRISC-V: KVM: Add common kvm_riscv_vcpu_sbi_system_reset() function
Anup Patel [Mon, 31 Jan 2022 04:59:31 +0000 (10:29 +0530)]
RISC-V: KVM: Add common kvm_riscv_vcpu_sbi_system_reset() function

We rename kvm_sbi_system_shutdown() to kvm_riscv_vcpu_sbi_system_reset()
and move it to vcpu_sbi.c so that it can be shared by SBI v0.1 shutdown
and SBI v0.3 SRST extension.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>