Avi Kivity wrote:
Alexander Graf wrote:
+ pr_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
+ __func__, data);
We can avoid the printout if data == 0, since we support that case
fully.
I was thinking a lot about that. Even though we support data == 0,
usually the kernel log output is useful for people trying to find if
something is cause a problem. If they see that DEBUGCTL gets set, but
won't see it getting unset, they'd get confused IMHO.
So the current behavior is on purpose, but if you oppose to that
idea, please tell me.
Once it gets set, you can expect brokenness. It doesn't matter if it
gets unset later. So IMO not printing on data == 0 is best: quiet on
the cases we support, and loud on cases we don't. So yes, I'd prefer
it changed.
Corrected patch follows...
---
Netware writes to DEBUGCTL and reads from the DEBUGCTL and LAST*IP MSRs
without further checks and is really confused to receive a #GP during
that. To make it happy we should just make them stubs, which is exactly
what SVM already does.
Writes to DEBUGCTL that are vendor-specific are resembled to behave as
if the virtual CPU does not know them.
Signed-off-by: Alexander Graf <[EMAIL PROTECTED]>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fc0721e..10f5e95 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -609,6 +609,15 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
pr_unimpl(vcpu, "%s: MSR_IA32_MCG_CTL 0x%llx, nop\n",
__func__, data);
break;
+ case MSR_IA32_DEBUGCTLMSR:
+ if (!data) {
+ /* We support the non-activated case already */
+ break;
+ } else if (data & ~(DEBUGCTLMSR_LBR | DEBUGCTLMSR_BTF)) {
+ /* Values other than LBR and BTF are vendor-specific,
+ thus reserved and should throw a #GP */
+ return 1;
+ }
+ pr_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
+ __func__, data);
+ break;
case MSR_IA32_UCODE_REV:
case MSR_IA32_UCODE_WRITE:
break;
@@ -705,6 +714,11 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
case MSR_IA32_MC0_MISC+16:
case MSR_IA32_UCODE_REV:
case MSR_IA32_EBL_CR_POWERON:
+ case MSR_IA32_DEBUGCTLMSR:
+ case MSR_IA32_LASTBRANCHFROMIP:
+ case MSR_IA32_LASTBRANCHTOIP:
+ case MSR_IA32_LASTINTFROMIP:
+ case MSR_IA32_LASTINTTOIP:
data = 0;
break;
case MSR_MTRRcap:
