| Message ID | 20230503041631.3368796-1-mizhang@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: VMX: add MSR_IA32_TSX_CTRL into msrs_to_save | expand |
On Wed, May 03, 2023, Mingwei Zhang wrote: > Add MSR_IA32_TSX_CTRL into msrs_to_save[] to explicitly tell userspace to > save/restore the register value during migration. Missing this may cause > userspace that relies on KVM ioctl(KVM_GET_MSR_INDEX_LIST) fail to port the > value to the target VM. > > Fixes: b07a5c53d42a ("KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it") > Reported-by: Jim Mattson <jmattson@google.com> > Signed-off-by: Mingwei Zhang <mizhang@google.com> > --- > arch/x86/kvm/x86.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 237c483b1230..2236cfee4b7a 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1431,7 +1431,7 @@ static const u32 msrs_to_save_base[] = { > #endif > MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA, > MSR_IA32_FEAT_CTL, MSR_IA32_BNDCFGS, MSR_TSC_AUX, > - MSR_IA32_SPEC_CTRL, > + MSR_IA32_SPEC_CTRL, MSR_IA32_TSX_CTRL, > MSR_IA32_RTIT_CTL, MSR_IA32_RTIT_STATUS, MSR_IA32_RTIT_CR3_MATCH, > MSR_IA32_RTIT_OUTPUT_BASE, MSR_IA32_RTIT_OUTPUT_MASK, > MSR_IA32_RTIT_ADDR0_A, MSR_IA32_RTIT_ADDR0_B, > -- Hmm, KVM shouldn't report the MSR if it can't be written by the guest. Over- reporting won't cause functional issues, and the odds of the MSR existing but not being reported in ARCH_CAPILIBITES are basically zilch, but IMO it's worth adding the check if only to document when the MSRs is fully supported. diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e7f78fe79b32..d8608c6753ff 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7152,6 +7152,10 @@ static void kvm_probe_msr_to_save(u32 msr_index) if (!kvm_cpu_cap_has(X86_FEATURE_XFD)) return; break; + case MSR_IA32_TSX_CTRL: + if (!(kvm_get_arch_capabilities() & ARCH_CAP_TSX_CTRL_MSR)) + return; + break; default: break; }
On Wed, May 3, 2023 at 9:25 AM Sean Christopherson <seanjc@google.com> wrote: > > On Wed, May 03, 2023, Mingwei Zhang wrote: > > Add MSR_IA32_TSX_CTRL into msrs_to_save[] to explicitly tell userspace to > > save/restore the register value during migration. Missing this may cause > > userspace that relies on KVM ioctl(KVM_GET_MSR_INDEX_LIST) fail to port the > > value to the target VM. > > > > Fixes: b07a5c53d42a ("KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it") > > Reported-by: Jim Mattson <jmattson@google.com> > > Signed-off-by: Mingwei Zhang <mizhang@google.com> > > --- > > arch/x86/kvm/x86.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 237c483b1230..2236cfee4b7a 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -1431,7 +1431,7 @@ static const u32 msrs_to_save_base[] = { > > #endif > > MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA, > > MSR_IA32_FEAT_CTL, MSR_IA32_BNDCFGS, MSR_TSC_AUX, > > - MSR_IA32_SPEC_CTRL, > > + MSR_IA32_SPEC_CTRL, MSR_IA32_TSX_CTRL, > > MSR_IA32_RTIT_CTL, MSR_IA32_RTIT_STATUS, MSR_IA32_RTIT_CR3_MATCH, > > MSR_IA32_RTIT_OUTPUT_BASE, MSR_IA32_RTIT_OUTPUT_MASK, > > MSR_IA32_RTIT_ADDR0_A, MSR_IA32_RTIT_ADDR0_B, > > -- > > Hmm, KVM shouldn't report the MSR if it can't be written by the guest. Over- I think you mean to say that KVM shouldn't report the MSR if it can't be written by *any* guest. KVM_GET_MSR_INDEX_LIST is a device ioctl, so it isn't capable of filtering out MSRs that can't be written by *the* guest, for some occurrence of "the." > reporting won't cause functional issues, and the odds of the MSR existing but not > being reported in ARCH_CAPILIBITES are basically zilch, but IMO it's worth adding > the check if only to document when the MSRs is fully supported. > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index e7f78fe79b32..d8608c6753ff 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -7152,6 +7152,10 @@ static void kvm_probe_msr_to_save(u32 msr_index) > if (!kvm_cpu_cap_has(X86_FEATURE_XFD)) > return; > break; > + case MSR_IA32_TSX_CTRL: > + if (!(kvm_get_arch_capabilities() & ARCH_CAP_TSX_CTRL_MSR)) > + return; > + break; > default: > break; > }
On Wed, May 03, 2023, Jim Mattson wrote: > On Wed, May 3, 2023 at 9:25 AM Sean Christopherson <seanjc@google.com> wrote: > > > > On Wed, May 03, 2023, Mingwei Zhang wrote: > > > Add MSR_IA32_TSX_CTRL into msrs_to_save[] to explicitly tell userspace to > > > save/restore the register value during migration. Missing this may cause > > > userspace that relies on KVM ioctl(KVM_GET_MSR_INDEX_LIST) fail to port the > > > value to the target VM. > > > > > > Fixes: b07a5c53d42a ("KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it") > > > Reported-by: Jim Mattson <jmattson@google.com> > > > Signed-off-by: Mingwei Zhang <mizhang@google.com> > > > --- > > > arch/x86/kvm/x86.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > > index 237c483b1230..2236cfee4b7a 100644 > > > --- a/arch/x86/kvm/x86.c > > > +++ b/arch/x86/kvm/x86.c > > > @@ -1431,7 +1431,7 @@ static const u32 msrs_to_save_base[] = { > > > #endif > > > MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA, > > > MSR_IA32_FEAT_CTL, MSR_IA32_BNDCFGS, MSR_TSC_AUX, > > > - MSR_IA32_SPEC_CTRL, > > > + MSR_IA32_SPEC_CTRL, MSR_IA32_TSX_CTRL, > > > MSR_IA32_RTIT_CTL, MSR_IA32_RTIT_STATUS, MSR_IA32_RTIT_CR3_MATCH, > > > MSR_IA32_RTIT_OUTPUT_BASE, MSR_IA32_RTIT_OUTPUT_MASK, > > > MSR_IA32_RTIT_ADDR0_A, MSR_IA32_RTIT_ADDR0_B, > > > -- > > > > Hmm, KVM shouldn't report the MSR if it can't be written by the guest. Over- > > I think you mean to say that KVM shouldn't report the MSR if it can't > be written by *any* guest. KVM_GET_MSR_INDEX_LIST is a device ioctl, > so it isn't capable of filtering out MSRs that can't be written by > *the* guest, for some occurrence of "the." Doh, yes, "the guest" was a handwavy reference to any/all guests.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 237c483b1230..2236cfee4b7a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1431,7 +1431,7 @@ static const u32 msrs_to_save_base[] = { #endif MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA, MSR_IA32_FEAT_CTL, MSR_IA32_BNDCFGS, MSR_TSC_AUX, - MSR_IA32_SPEC_CTRL, + MSR_IA32_SPEC_CTRL, MSR_IA32_TSX_CTRL, MSR_IA32_RTIT_CTL, MSR_IA32_RTIT_STATUS, MSR_IA32_RTIT_CR3_MATCH, MSR_IA32_RTIT_OUTPUT_BASE, MSR_IA32_RTIT_OUTPUT_MASK, MSR_IA32_RTIT_ADDR0_A, MSR_IA32_RTIT_ADDR0_B,
Add MSR_IA32_TSX_CTRL into msrs_to_save[] to explicitly tell userspace to save/restore the register value during migration. Missing this may cause userspace that relies on KVM ioctl(KVM_GET_MSR_INDEX_LIST) fail to port the value to the target VM. Fixes: b07a5c53d42a ("KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it") Reported-by: Jim Mattson <jmattson@google.com> Signed-off-by: Mingwei Zhang <mizhang@google.com> --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)