| Message ID | 1242375740-31222-5-git-send-email-agraf@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Alexander Graf wrote: > Hyper-V uses some MSRs, some of which are actually reserved for BIOS usage. > > But let's be nice today and have it its way, because otherwise it fails > terribly. > > For MSRs where I could find a name I used the name, otherwise they're just > added in their hex form for now. > > Most of these are not Hyper-V MSRs. They are x86 MSRs that happen to be hit by Hyper-v. > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index ef43a18..30e6b43 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -1932,6 +1932,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data) > *data = svm->hsave_msr; > break; > case MSR_VM_CR: > + case 0x40000081: > *data = 0; > break; > This probably is a Hyper-V MSR, but I don't see how it expects it to be present in real hardware. Are you sure this is really needed? > @@ -2034,6 +2035,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data) > case MSR_VM_HSAVE_PA: > svm->hsave_msr = data; > break; > + case MSR_VM_CR: > + case MSR_VM_IGNNE: > + case MSR_K8_HWCR: > + break; > Please add a ratelimited printk() if any value is written which would cause behaviour which we do not emulate. This will prevent a guest getting unexpected behaviour silently.
On 17.05.2009, at 11:54, Avi Kivity <avi@redhat.com> wrote: > Alexander Graf wrote: >> Hyper-V uses some MSRs, some of which are actually reserved for >> BIOS usage. >> >> But let's be nice today and have it its way, because otherwise it >> fails >> terribly. >> >> For MSRs where I could find a name I used the name, otherwise >> they're just >> added in their hex form for now. >> >> > > Most of these are not Hyper-V MSRs. They are x86 MSRs that happen > to be hit by Hyper-v. > > >> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c >> index ef43a18..30e6b43 100644 >> --- a/arch/x86/kvm/svm.c >> +++ b/arch/x86/kvm/svm.c >> @@ -1932,6 +1932,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, >> unsigned ecx, u64 *data) >> *data = svm->hsave_msr; >> break; >> case MSR_VM_CR: >> + case 0x40000081: >> *data = 0; >> break; >> > > This probably is a Hyper-V MSR, but I don't see how it expects it to > be present in real hardware. Are you sure this is really needed? Well hyper-v just crashes/reboots if it get a #gp on that msr, so I suppose yes. > > >> @@ -2034,6 +2035,10 @@ static int svm_set_msr(struct kvm_vcpu >> *vcpu, unsigned ecx, u64 data) >> case MSR_VM_HSAVE_PA: >> svm->hsave_msr = data; >> break; >> + case MSR_VM_CR: >> + case MSR_VM_IGNNE: >> + case MSR_K8_HWCR: >> + break; >> > > Please add a ratelimited printk() if any value is written which > would cause behaviour which we do not emulate. This will prevent a > guest getting unexpected behaviour silently. Right. Good catch. Alex > > > -- > error compiling committee.c: too many arguments to function > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Alexander Graf wrote: >>> case MSR_VM_CR: >>> + case 0x40000081: >>> *data = 0; >>> break; >>> >> >> This probably is a Hyper-V MSR, but I don't see how it expects it to >> be present in real hardware. Are you sure this is really needed? > > Well hyper-v just crashes/reboots if it get a #gp on that msr, so I > suppose yes. This is suspicious. It won't get this MSR on real hardware. Maybe this was with cpuid.hypervisor enabled?
On 17.05.2009, at 22:00, Avi Kivity <avi@redhat.com> wrote: > Alexander Graf wrote: >>>> case MSR_VM_CR: >>>> + case 0x40000081: >>>> *data = 0; >>>> break; >>>> >>> >>> This probably is a Hyper-V MSR, but I don't see how it expects it >>> to be present in real hardware. Are you sure this is really needed? >> >> Well hyper-v just crashes/reboots if it get a #gp on that msr, so I >> suppose yes. > > This is suspicious. It won't get this MSR on real hardware. > > Maybe this was with cpuid.hypervisor enabled? Before I sent out this patch I rechecked if the 0x4 msr is really required because it seemed awkward to me too and it did, but I can recheck for a 3rd time :) Alex > > > -- > Do not meddle in the internals of kernels, for they are subtle and > quick to panic. > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 17.05.2009, at 22:00, Avi Kivity <avi@redhat.com> wrote: > Alexander Graf wrote: >>>> case MSR_VM_CR: >>>> + case 0x40000081: >>>> *data = 0; >>>> break; >>>> >>> >>> This probably is a Hyper-V MSR, but I don't see how it expects it >>> to be present in real hardware. Are you sure this is really needed? >> >> Well hyper-v just crashes/reboots if it get a #gp on that msr, so I >> suppose yes. > > This is suspicious. It won't get this MSR on real hardware. > > Maybe this was with cpuid.hypervisor enabled? Hm - seems to boot fine without. Oh well :). Alex > > > -- > Do not meddle in the internals of kernels, for they are subtle and > quick to panic. > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index ef43a18..30e6b43 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1932,6 +1932,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data) *data = svm->hsave_msr; break; case MSR_VM_CR: + case 0x40000081: *data = 0; break; case MSR_IA32_UCODE_REV: @@ -2034,6 +2035,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data) case MSR_VM_HSAVE_PA: svm->hsave_msr = data; break; + case MSR_VM_CR: + case MSR_VM_IGNNE: + case MSR_K8_HWCR: + break; default: return kvm_set_msr_common(vcpu, ecx, data); }
Hyper-V uses some MSRs, some of which are actually reserved for BIOS usage. But let's be nice today and have it its way, because otherwise it fails terribly. For MSRs where I could find a name I used the name, otherwise they're just added in their hex form for now. Signed-off-by: Alexander Graf <agraf@suse.de> --- arch/x86/kvm/svm.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-)