Re: [PATCH 2/4] Implement Hyper-V MSRs v2

[Avi Kivity <avi@redhat.com>]

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.
>
> v2 changes:
>   - remove the 0x40000081 MSR definition
>   - add pr_unimpl() on unimplemented writes
>
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  arch/x86/kvm/svm.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index ef43a18..4b4eadd 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2034,6 +2034,11 @@ 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:
> +		pr_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", ecx, data);
> +		break;
>   

We can be nicer, if the write doesn't set bits which we don't implement, 
we can let it proceed silently.  See for example MSR_IA32_DEBUGCTLMSR.  
Most likely the values written are already correctly implemented (by 
doing nothing).

-- 
error compiling committee.c: too many arguments to function