| Message ID | 20240605114810.1304-1-ravi.bangoria@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: SNP: Fix LBR Virtualization for SNP guest | expand |
On Wed, Jun 5, 2024 at 1:49 PM Ravi Bangoria <ravi.bangoria@amd.com> wrote: > > SEV-ES and thus SNP guest mandates LBR Virtualization to be _always_ ON. > Although commit b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization > to the processor") did the correct change for SEV-ES guests, it missed > the SNP. Fix it. > > Reported-by: Srikanth Aithal <sraithal@amd.com> > Fixes: b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization to the processor") > Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com> > --- > - SNP support was not present while I prepared the original patches and > that lead to this confusion. Sorry about that. No problem, this is a semantic conflict and your original patches will go in 6.10. Applied to kvm/next. Paolo > arch/x86/kvm/svm/sev.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 7d401f8a3001..57291525e084 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -2395,6 +2395,14 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) > } > > svm->vcpu.arch.guest_state_protected = true; > + /* > + * SEV-ES (and thus SNP) guest mandates LBR Virtualization to > + * be _always_ ON. Enable it only after setting > + * guest_state_protected because KVM_SET_MSRS allows dynamic > + * toggling of LBRV (for performance reason) on write access to > + * MSR_IA32_DEBUGCTLMSR when guest_state_protected is not set. > + */ > + svm_enable_lbrv(vcpu); > } > > return 0; > -- > 2.45.1 >
On 6/5/2024 5:18 PM, Ravi Bangoria wrote: > SEV-ES and thus SNP guest mandates LBR Virtualization to be _always_ ON. > Although commit b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization > to the processor") did the correct change for SEV-ES guests, it missed > the SNP. Fix it. > > Reported-by: Srikanth Aithal <sraithal@amd.com> > Fixes: b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization to the processor") > Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com> > --- > - SNP support was not present while I prepared the original patches and > that lead to this confusion. Sorry about that. > > arch/x86/kvm/svm/sev.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 7d401f8a3001..57291525e084 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -2395,6 +2395,14 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) > } > > svm->vcpu.arch.guest_state_protected = true; > + /* > + * SEV-ES (and thus SNP) guest mandates LBR Virtualization to > + * be _always_ ON. Enable it only after setting > + * guest_state_protected because KVM_SET_MSRS allows dynamic > + * toggling of LBRV (for performance reason) on write access to > + * MSR_IA32_DEBUGCTLMSR when guest_state_protected is not set. > + */ > + svm_enable_lbrv(vcpu); > } > > return 0; Tested-by: Srikanth Aithal <sraithal@amd.com>
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 7d401f8a3001..57291525e084 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2395,6 +2395,14 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) } svm->vcpu.arch.guest_state_protected = true; + /* + * SEV-ES (and thus SNP) guest mandates LBR Virtualization to + * be _always_ ON. Enable it only after setting + * guest_state_protected because KVM_SET_MSRS allows dynamic + * toggling of LBRV (for performance reason) on write access to + * MSR_IA32_DEBUGCTLMSR when guest_state_protected is not set. + */ + svm_enable_lbrv(vcpu); } return 0;
SEV-ES and thus SNP guest mandates LBR Virtualization to be _always_ ON. Although commit b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization to the processor") did the correct change for SEV-ES guests, it missed the SNP. Fix it. Reported-by: Srikanth Aithal <sraithal@amd.com> Fixes: b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization to the processor") Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com> --- - SNP support was not present while I prepared the original patches and that lead to this confusion. Sorry about that. arch/x86/kvm/svm/sev.c | 8 ++++++++ 1 file changed, 8 insertions(+)