| Message ID | ff66ee115d05d698813f54e10497698da21d1b73.1600114548.git.thomas.lendacky@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | SEV-ES hypervisor support | expand |
On Mon, Sep 14, 2020 at 03:15:42PM -0500, Tom Lendacky wrote: > From: Tom Lendacky <thomas.lendacky@amd.com> > > The register state for an SEV-ES guest is encrypted so the value of the > RIP cannot be updated. For an automatic exit, the RIP will be advanced > as necessary. For a non-automatic exit, it is up to the #VC handler in > the guest to advance the RIP. > > Add support to skip any RIP updates in kvm_skip_emulated_instruction() > for an SEV-ES guest. Is there a reason this can't be handled in svm? E.g. can KVM be reworked to effectively split the emulation logic so that it's a bug for KVM to end up trying to modify RIP? Also, patch 06 modifies SVM's skip_emulated_instruction() to skip the RIP update, but keeps the "svm_set_interrupt_shadow(vcpu, 0)" logic. Seems like either that change or this one is wrong. > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> > --- > arch/x86/kvm/x86.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 23564d02d158..1dbdca607511 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6874,13 +6874,17 @@ static int kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu) > > int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu) > { > - unsigned long rflags = kvm_x86_ops.get_rflags(vcpu); > + unsigned long rflags; > int r; > > r = kvm_x86_ops.skip_emulated_instruction(vcpu); > if (unlikely(!r)) > return 0; > > + if (vcpu->arch.vmsa_encrypted) > + return 1; > + > + rflags = kvm_x86_ops.get_rflags(vcpu); > /* > * rflags is the old, "raw" value of the flags. The new value has > * not been saved yet. > -- > 2.28.0 >
On 9/14/20 4:51 PM, Sean Christopherson wrote: > On Mon, Sep 14, 2020 at 03:15:42PM -0500, Tom Lendacky wrote: >> From: Tom Lendacky <thomas.lendacky@amd.com> >> >> The register state for an SEV-ES guest is encrypted so the value of the >> RIP cannot be updated. For an automatic exit, the RIP will be advanced >> as necessary. For a non-automatic exit, it is up to the #VC handler in >> the guest to advance the RIP. >> >> Add support to skip any RIP updates in kvm_skip_emulated_instruction() >> for an SEV-ES guest. > > Is there a reason this can't be handled in svm? E.g. can KVM be reworked > to effectively split the emulation logic so that it's a bug for KVM to end > up trying to modify RIP? > > Also, patch 06 modifies SVM's skip_emulated_instruction() to skip the RIP > update, but keeps the "svm_set_interrupt_shadow(vcpu, 0)" logic. Seems like > either that change or this one is wrong. I added this because of the get_rflags() call. But let me look into changing get_rflags() in svm.c and see if this patch can go away. Thanks, Tom > >> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> >> --- >> arch/x86/kvm/x86.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 23564d02d158..1dbdca607511 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -6874,13 +6874,17 @@ static int kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu) >> >> int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu) >> { >> - unsigned long rflags = kvm_x86_ops.get_rflags(vcpu); >> + unsigned long rflags; >> int r; >> >> r = kvm_x86_ops.skip_emulated_instruction(vcpu); >> if (unlikely(!r)) >> return 0; >> >> + if (vcpu->arch.vmsa_encrypted) >> + return 1; >> + >> + rflags = kvm_x86_ops.get_rflags(vcpu); >> /* >> * rflags is the old, "raw" value of the flags. The new value has >> * not been saved yet. >> -- >> 2.28.0 >>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 23564d02d158..1dbdca607511 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6874,13 +6874,17 @@ static int kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu) int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu) { - unsigned long rflags = kvm_x86_ops.get_rflags(vcpu); + unsigned long rflags; int r; r = kvm_x86_ops.skip_emulated_instruction(vcpu); if (unlikely(!r)) return 0; + if (vcpu->arch.vmsa_encrypted) + return 1; + + rflags = kvm_x86_ops.get_rflags(vcpu); /* * rflags is the old, "raw" value of the flags. The new value has * not been saved yet.