Re: [PATCH v3 2/8] x86/svm: silently drop writes to SYSCFG and related MSRs

[Jan Beulich <jbeulich@xxxxxxxx>]

On 01.09.2020 12:54, Roger Pau Monne wrote:
> The SYSCFG, TOP_MEM1 and TOP_MEM2 MSRs are currently exposed to guests
> and writes are silently discarded. Make this explicit in the SVM code
> now, and just return default constant values when attempting to read
> any of the MSRs, while continuing to silently drop writes.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -1917,6 +1917,9 @@ static int svm_msr_read_intercept(unsigned int msr, 
> uint64_t *msr_content)
>              goto gpf;
>          break;
>  
> +    case MSR_K8_SYSCFG:
> +    case MSR_K8_TOP_MEM1:
> +    case MSR_K8_TOP_MEM2:
>      case MSR_K8_VM_CR:
>          *msr_content = 0;
>          break;

Andrew, since you did suggest otherwise before, may I ask for an
explicit statement of yours here, be it in ack/nak form or something
less formal?

Jan