Re: [Xen-devel] [PATCH v1 5/6] VMX: Disable SMAP feature when guest is in non-paging mode

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Wednesday, April 16, 2014 4:52 PM
> To: Wu, Feng
> Cc: Ian.Campbell@xxxxxxxxxx; Dong, Eddie; Nakajima, Jun;
> xen-devel@xxxxxxxxxxxxx
> Subject: RE: [PATCH v1 5/6] VMX: Disable SMAP feature when guest is in
> non-paging mode
> 
> >>> On 16.04.14 at 04:07, <feng.wu@xxxxxxxxx> wrote:
> 
> >
> >> -----Original Message-----
> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> Sent: Tuesday, April 15, 2014 7:51 PM
> >> To: Wu, Feng
> >> Cc: Ian.Campbell@xxxxxxxxxx; Dong, Eddie; Nakajima, Jun;
> >> xen-devel@xxxxxxxxxxxxx
> >> Subject: Re: [PATCH v1 5/6] VMX: Disable SMAP feature when guest is in
> >> non-paging mode
> >>
> >> >>> On 15.04.14 at 15:02, <feng.wu@xxxxxxxxx> wrote:
> >> > SMAP is disabled if CPU is in non-paging mode in hardware.
> >> > However Xen always uses paging mode to emulate guest non-paging
> >> > mode with HAP. To emulate this behavior, SMAP needs to be manually
> >> > disabled when guest switches to non-paging mode.
> >> >
> >> > This logic is similiar with SMEP.
> >>
> >> The change is certainly fine, but shouldn't this be done earlier in the
> >> series (i.e. the patch moved up)?
> >
> > Yes, maybe we should put it right before
> > "v1-0004-x86-hvm-Add-SMAP-support-to-HVM-guest.patch",
> > since this changes is for HVM guest. what do you think of this? Thanks!
> 
> The change here needs to be done prior (or along with) the feature
> getting enabled for the host, whenever that is in the series.

Okay, will change the order in the next version.

> 
> Jan

Thanks,
Feng

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