Re: [Xen-devel] [PATCH 4/6] x86: stop handling MSR_IA32_XSS save/restore in implementation code

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 08 March 2019 16:47
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Roger Pau Monne 
> <roger.pau@xxxxxxxxxx>; Wei Liu
> <wei.liu2@xxxxxxxxxx>; Jun Nakajima <jun.nakajima@xxxxxxxxx>; Kevin Tian 
> <kevin.tian@xxxxxxxxx>; xen-
> devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> Subject: Re: [PATCH 4/6] x86: stop handling MSR_IA32_XSS save/restore in 
> implementation code
> 
> >>> On 07.01.19 at 13:02, <paul.durrant@xxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/msr.c
> > +++ b/xen/arch/x86/msr.c
> > @@ -164,6 +164,13 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t 
> > *val)
> >
> >          break;
> >
> > +    case MSR_IA32_XSS:
> > +        if ( !is_hvm_domain(d) || !cp->xstate.xsaves )
> 
> Why the is_hvm_domain() check here and below?

Only there because the older code was HVM-specific.

> The CPUID policy bit
> alone should properly reflect things, and there should be no change
> needed here if we decided to support XSAVES also for PV guests. With
> them dropped
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Ok. Thanks,

  Paul

> 
> Jan
> 


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