KVM: SVM: Fix TSC_AUX virtualization setup

commit e0096d01c4fcb8c96c05643cfc2c20ab78eae4da upstream.

The checks for virtualizing TSC_AUX occur during the vCPU reset processing
path. However, at the time of initial vCPU reset processing, when the vCPU
is first created, not all of the guest CPUID information has been set. In
this case the RDTSCP and RDPID feature support for the guest is not in
place and so TSC_AUX virtualization is not established.

This continues for each vCPU created for the guest. On the first boot of
an AP, vCPU reset processing is executed as a result of an APIC INIT
event, this time with all of the guest CPUID information set, resulting
in TSC_AUX virtualization being enabled, but only for the APs. The BSP
always sees a TSC_AUX value of 0 which probably went unnoticed because,
at least for Linux, the BSP TSC_AUX value is 0.

Move the TSC_AUX virtualization enablement out of the init_vmcb() path and
into the vcpu_after_set_cpuid() path to allow for proper initialization of
the support after the guest CPUID information has been set.

With the TSC_AUX virtualization support now in the vcpu_set_after_cpuid()
path, the intercepts must be either cleared or set based on the guest
CPUID input.

Fixes: 296d5a17e793 ("KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <4137fbcb9008951ab5f0befa74a0399d2cce809a.1694811272.git.thomas.lendacky@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index e0d14f964fe74d064f6ecedee2079188098f4552..3060fe4e9731aaa421970f0a271af65a73d286e4 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2941,6 +2941,32 @@ int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in)
                                    count, in);
 }
 
+static void sev_es_vcpu_after_set_cpuid(struct vcpu_svm *svm)
+{
+       struct kvm_vcpu *vcpu = &svm->vcpu;
+
+       if (boot_cpu_has(X86_FEATURE_V_TSC_AUX)) {
+               bool v_tsc_aux = guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) ||
+                                guest_cpuid_has(vcpu, X86_FEATURE_RDPID);
+
+               set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, v_tsc_aux, v_tsc_aux);
+       }
+}
+
+void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm)
+{
+       struct kvm_vcpu *vcpu = &svm->vcpu;
+       struct kvm_cpuid_entry2 *best;
+
+       /* For sev guests, the memory encryption bit is not reserved in CR3.  */
+       best = kvm_find_cpuid_entry(vcpu, 0x8000001F);
+       if (best)
+               vcpu->arch.reserved_gpa_bits &= ~(1UL << (best->ebx & 0x3f));
+
+       if (sev_es_guest(svm->vcpu.kvm))
+               sev_es_vcpu_after_set_cpuid(svm);
+}
+
 static void sev_es_init_vmcb(struct vcpu_svm *svm)
 {
        struct kvm_vcpu *vcpu = &svm->vcpu;
@@ -2987,11 +3013,6 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm)
        set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTBRANCHTOIP, 1, 1);
        set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTFROMIP, 1, 1);
        set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTTOIP, 1, 1);
-
-       if (boot_cpu_has(X86_FEATURE_V_TSC_AUX) &&
-           (guest_cpuid_has(&svm->vcpu, X86_FEATURE_RDTSCP) ||
-            guest_cpuid_has(&svm->vcpu, X86_FEATURE_RDPID)))
-               set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, 1, 1);
 }
 
 void sev_init_vmcb(struct vcpu_svm *svm)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7e4d66be18ef596687e8b5c330190fe395a69519..c871a6d6364ca4710bcf4da43ee32b1dad8c3bc1 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4173,7 +4173,6 @@ static bool svm_has_emulated_msr(struct kvm *kvm, u32 index)
 static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 {
        struct vcpu_svm *svm = to_svm(vcpu);
-       struct kvm_cpuid_entry2 *best;
 
        vcpu->arch.xsaves_enabled = guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) &&
                                    boot_cpu_has(X86_FEATURE_XSAVE) &&
@@ -4198,12 +4197,8 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 
        svm_recalc_instruction_intercepts(vcpu, svm);
 
-       /* For sev guests, the memory encryption bit is not reserved in CR3.  */
-       if (sev_guest(vcpu->kvm)) {
-               best = kvm_find_cpuid_entry(vcpu, 0x8000001F);
-               if (best)
-                       vcpu->arch.reserved_gpa_bits &= ~(1UL << (best->ebx & 0x3f));
-       }
+       if (sev_guest(vcpu->kvm))
+               sev_vcpu_after_set_cpuid(svm);
 
        init_vmcb_after_set_cpuid(vcpu);
 }

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 62f87492763e07e26c7aa05f3cd7eb20c7660025..4cb1425900c6da402a7726338fce7faefd8e8f01 100644 (file)
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -677,6 +677,7 @@ void __init sev_hardware_setup(void);
 void sev_hardware_unsetup(void);
 int sev_cpu_init(struct svm_cpu_data *sd);
 void sev_init_vmcb(struct vcpu_svm *svm);
+void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm);
 void sev_free_vcpu(struct kvm_vcpu *vcpu);
 int sev_handle_vmgexit(struct kvm_vcpu *vcpu);
 int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);