| Message ID | 20200529153934.11694-26-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: nSVM: event fixes and migration support | expand |
On 5/29/20 8:39 AM, Paolo Bonzini wrote: > According to the AMD manual, the effect of turning off EFER.SVME while a > guest is running is undefined. We make it leave guest mode immediately, > similar to the effect of clearing the VMX bit in MSR_IA32_FEAT_CTL. I see that svm_set_efer() is called in enter_svm_guest_mode() and nested_svm_vmexit(). In the VMRUN path, we have already checked EFER.SVME in nested_vmcb_checks(). So if it was not set, we wouldn't come to enter_svm_guest_mode(). Your fix is only for the #VMEXIT path then ? > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/kvm/svm/nested.c | 16 ++++++++++++++++ > arch/x86/kvm/svm/svm.c | 10 ++++++++-- > arch/x86/kvm/svm/svm.h | 1 + > 3 files changed, 25 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c > index bd3a89cd4070..369eca73fe3e 100644 > --- a/arch/x86/kvm/svm/nested.c > +++ b/arch/x86/kvm/svm/nested.c > @@ -618,6 +618,22 @@ int nested_svm_vmexit(struct vcpu_svm *svm) > return 0; > } > > +/* > + * Forcibly leave nested mode in order to be able to reset the VCPU later on. > + */ > +void svm_leave_nested(struct vcpu_svm *svm) > +{ > + if (is_guest_mode(&svm->vcpu)) { > + struct vmcb *hsave = svm->nested.hsave; > + struct vmcb *vmcb = svm->vmcb; > + > + svm->nested.nested_run_pending = 0; > + leave_guest_mode(&svm->vcpu); > + copy_vmcb_control_area(&vmcb->control, &hsave->control); > + nested_svm_uninit_mmu_context(&svm->vcpu); > + } > +} > + > static int nested_svm_exit_handled_msr(struct vcpu_svm *svm) > { > u32 offset, msr, value; > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index bc08221f6743..b4db9a980469 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -265,6 +265,7 @@ static int get_npt_level(struct kvm_vcpu *vcpu) > > void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer) > { > + struct vcpu_svm *svm = to_svm(vcpu); > vcpu->arch.efer = efer; > > if (!npt_enabled) { > @@ -275,8 +276,13 @@ void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer) > efer &= ~EFER_LME; > } > > - to_svm(vcpu)->vmcb->save.efer = efer | EFER_SVME; > - mark_dirty(to_svm(vcpu)->vmcb, VMCB_CR); > + if (!(efer & EFER_SVME)) { > + svm_leave_nested(svm); > + svm_set_gif(svm, true); > + } > + > + svm->vmcb->save.efer = efer | EFER_SVME; > + mark_dirty(svm->vmcb, VMCB_CR); > } > > static int is_external_interrupt(u32 info) > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index be8e830f83fa..6ac4c00a5d82 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -389,6 +389,7 @@ static inline bool nested_exit_on_nmi(struct vcpu_svm *svm) > > void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa, > struct vmcb *nested_vmcb); > +void svm_leave_nested(struct vcpu_svm *svm); > int nested_svm_vmrun(struct vcpu_svm *svm); > void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb); > int nested_svm_vmexit(struct vcpu_svm *svm);
On 01/06/20 04:26, Krish Sadhukhan wrote: > On 5/29/20 8:39 AM, Paolo Bonzini wrote: >> According to the AMD manual, the effect of turning off EFER.SVME while a >> guest is running is undefined. We make it leave guest mode immediately, >> similar to the effect of clearing the VMX bit in MSR_IA32_FEAT_CTL. > > I see that svm_set_efer() is called in enter_svm_guest_mode() and > nested_svm_vmexit(). In the VMRUN path, we have already checked > EFER.SVME in nested_vmcb_checks(). So if it was not set, we wouldn't > come to enter_svm_guest_mode(). Your fix is only for the #VMEXIT path > then ? No, it's for KVM_SET_MSR. Paolo
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index bd3a89cd4070..369eca73fe3e 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -618,6 +618,22 @@ int nested_svm_vmexit(struct vcpu_svm *svm) return 0; } +/* + * Forcibly leave nested mode in order to be able to reset the VCPU later on. + */ +void svm_leave_nested(struct vcpu_svm *svm) +{ + if (is_guest_mode(&svm->vcpu)) { + struct vmcb *hsave = svm->nested.hsave; + struct vmcb *vmcb = svm->vmcb; + + svm->nested.nested_run_pending = 0; + leave_guest_mode(&svm->vcpu); + copy_vmcb_control_area(&vmcb->control, &hsave->control); + nested_svm_uninit_mmu_context(&svm->vcpu); + } +} + static int nested_svm_exit_handled_msr(struct vcpu_svm *svm) { u32 offset, msr, value; diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index bc08221f6743..b4db9a980469 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -265,6 +265,7 @@ static int get_npt_level(struct kvm_vcpu *vcpu) void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer) { + struct vcpu_svm *svm = to_svm(vcpu); vcpu->arch.efer = efer; if (!npt_enabled) { @@ -275,8 +276,13 @@ void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer) efer &= ~EFER_LME; } - to_svm(vcpu)->vmcb->save.efer = efer | EFER_SVME; - mark_dirty(to_svm(vcpu)->vmcb, VMCB_CR); + if (!(efer & EFER_SVME)) { + svm_leave_nested(svm); + svm_set_gif(svm, true); + } + + svm->vmcb->save.efer = efer | EFER_SVME; + mark_dirty(svm->vmcb, VMCB_CR); } static int is_external_interrupt(u32 info) diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index be8e830f83fa..6ac4c00a5d82 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -389,6 +389,7 @@ static inline bool nested_exit_on_nmi(struct vcpu_svm *svm) void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa, struct vmcb *nested_vmcb); +void svm_leave_nested(struct vcpu_svm *svm); int nested_svm_vmrun(struct vcpu_svm *svm); void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb); int nested_svm_vmexit(struct vcpu_svm *svm);
According to the AMD manual, the effect of turning off EFER.SVME while a guest is running is undefined. We make it leave guest mode immediately, similar to the effect of clearing the VMX bit in MSR_IA32_FEAT_CTL. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/svm/nested.c | 16 ++++++++++++++++ arch/x86/kvm/svm/svm.c | 10 ++++++++-- arch/x86/kvm/svm/svm.h | 1 + 3 files changed, 25 insertions(+), 2 deletions(-)