From 33719fb9cfe29466cb3966d679e42f004b210f02 Mon Sep 17 00:00:00 2001 From: "Maciej S. Szmigiero" Date: Mon, 2 May 2022 00:07:25 +0200 Subject: [PATCH] KVM: nSVM: Sync next_rip field from vmcb12 to vmcb02 The next_rip field of a VMCB is *not* an output-only field for a VMRUN. This field value (instead of the saved guest RIP) in used by the CPU for the return address pushed on stack when injecting a software interrupt or INT3 or INTO exception. Make sure this field gets synced from vmcb12 to vmcb02 when entering L2 or loading a nested state and NRIPS is exposed to L1. If NRIPS is supported in hardware but not exposed to L1 (nrips=0 or hidden by userspace), stuff vmcb02's next_rip from the new L2 RIP to emulate a !NRIPS CPU (which saves RIP on the stack as-is). Reviewed-by: Maxim Levitsky Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Signed-off-by: Maciej S. Szmigiero Message-Id: Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/nested.c | 22 +++++++++++++++++++--- arch/x86/kvm/svm/svm.h | 1 + 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 3361258640a27..e8aa95a74564a 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -371,6 +371,7 @@ void __nested_copy_vmcb_control_to_cache(struct kvm_vcpu *vcpu, to->nested_ctl = from->nested_ctl; to->event_inj = from->event_inj; to->event_inj_err = from->event_inj_err; + to->next_rip = from->next_rip; to->nested_cr3 = from->nested_cr3; to->virt_ext = from->virt_ext; to->pause_filter_count = from->pause_filter_count; @@ -608,7 +609,8 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 } } -static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) +static void nested_vmcb02_prepare_control(struct vcpu_svm *svm, + unsigned long vmcb12_rip) { u32 int_ctl_vmcb01_bits = V_INTR_MASKING_MASK; u32 int_ctl_vmcb12_bits = V_TPR_MASK | V_IRQ_INJECTION_BITS_MASK; @@ -662,6 +664,19 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) vmcb02->control.event_inj = svm->nested.ctl.event_inj; vmcb02->control.event_inj_err = svm->nested.ctl.event_inj_err; + /* + * next_rip is consumed on VMRUN as the return address pushed on the + * stack for injected soft exceptions/interrupts. If nrips is exposed + * to L1, take it verbatim from vmcb12. If nrips is supported in + * hardware but not exposed to L1, stuff the actual L2 RIP to emulate + * what a nrips=0 CPU would do (L1 is responsible for advancing RIP + * prior to injecting the event). + */ + if (svm->nrips_enabled) + vmcb02->control.next_rip = svm->nested.ctl.next_rip; + else if (boot_cpu_has(X86_FEATURE_NRIPS)) + vmcb02->control.next_rip = vmcb12_rip; + vmcb02->control.virt_ext = vmcb01->control.virt_ext & LBR_CTL_ENABLE_MASK; if (svm->lbrv_enabled) @@ -745,7 +760,7 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa, nested_svm_copy_common_state(svm->vmcb01.ptr, svm->nested.vmcb02.ptr); svm_switch_vmcb(svm, &svm->nested.vmcb02); - nested_vmcb02_prepare_control(svm); + nested_vmcb02_prepare_control(svm, vmcb12->save.rip); nested_vmcb02_prepare_save(svm, vmcb12); ret = nested_svm_load_cr3(&svm->vcpu, svm->nested.save.cr3, @@ -1418,6 +1433,7 @@ static void nested_copy_vmcb_cache_to_control(struct vmcb_control_area *dst, dst->nested_ctl = from->nested_ctl; dst->event_inj = from->event_inj; dst->event_inj_err = from->event_inj_err; + dst->next_rip = from->next_rip; dst->nested_cr3 = from->nested_cr3; dst->virt_ext = from->virt_ext; dst->pause_filter_count = from->pause_filter_count; @@ -1602,7 +1618,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, nested_copy_vmcb_control_to_cache(svm, ctl); svm_switch_vmcb(svm, &svm->nested.vmcb02); - nested_vmcb02_prepare_control(svm); + nested_vmcb02_prepare_control(svm, svm->vmcb->save.rip); /* * While the nested guest CR3 is already checked and set by diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 500348c1cb350..de076d658390c 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -139,6 +139,7 @@ struct vmcb_ctrl_area_cached { u64 nested_ctl; u32 event_inj; u32 event_inj_err; + u64 next_rip; u64 nested_cr3; u64 virt_ext; u32 clean; -- 2.39.5