Re: [Xen-devel] [PATCH 2/2] x86emul: in_longmode() should not ignore ->read_msr() errors

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 22/11/16 14:20, Jan Beulich wrote:
> Suggested-by: George Dunlap <george.dunlap@xxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Possibly worth nothing in the commit message that the current
implementation of this hook when present never fails with MSR_EFER?

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

>
> --- a/xen/arch/x86/x86_emulate/x86_emulate.c
> +++ b/xen/arch/x86/x86_emulate/x86_emulate.c
> @@ -1296,10 +1296,10 @@ in_longmode(
>  {
>      uint64_t efer;
>  
> -    if (ops->read_msr == NULL)
> +    if ( !ops->read_msr ||
> +         unlikely(ops->read_msr(MSR_EFER, &efer, ctxt) != X86EMUL_OKAY) )
>          return -1;
>  
> -    ops->read_msr(MSR_EFER, &efer, ctxt);
>      return !!(efer & EFER_LMA);
>  }
>  
>
>
>


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