Paolo Bonzini <pbonzini@xxxxxxxxxx> writes: > On 23/01/20 09:55, Vitaly Kuznetsov wrote: >>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c >>> index 7608924ee8c1..985d3307ec56 100644 >>> --- a/arch/x86/kvm/vmx/nested.c >>> +++ b/arch/x86/kvm/vmx/nested.c >>> @@ -5165,7 +5165,7 @@ static int handle_invvpid(struct kvm_vcpu *vcpu) >>> break; >>> default: >>> WARN_ON_ONCE(1); >>> - return kvm_skip_emulated_instruction(vcpu); >>> + break; >>> } >>> >>> return nested_vmx_succeed(vcpu); >> Your patch seems to do the right thing, however, I started wondering if >> WARN_ON_ONCE() is the right thing to do. SDM says that "If an >> unsupported INVVPID type is specified, the instruction fails." and this >> is similar to INVEPT and I decided to check what handle_invept() >> does. Well, it does BUG_ON(). >> >> Are we doing the right thing in any of these cases? > > Yes, both INVEPT and INVVPID catch this earlier. > > For INVEPT: > > types = (vmx->nested.msrs.ept_caps >> VMX_EPT_EXTENT_SHIFT) & 6; > > if (type >= 32 || !(types & (1 << type))) > return nested_vmx_failValid(vcpu, > VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID); > > > > For INVVPID: > > types = (vmx->nested.msrs.vpid_caps & > VMX_VPID_EXTENT_SUPPORTED_MASK) >> 8; > > if (type >= 32 || !(types & (1 << type))) > return nested_vmx_failValid(vcpu, > VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID); > Ah, true, thanks for checking! > So I'm leaning towards not applying Miaohe's patch. Well, we may at least want to converge on BUG_ON() for both handle_invvpid()/handle_invept(), there's no need for them to differ. -- Vitaly
