Re: [Xen-devel] [PATCH] tools/libxc: Add xstate cpuid leaf of avx512

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Nov 04, 2016 at 11:00:16AM +0000, Wei Liu wrote:
> On Fri, Nov 04, 2016 at 10:20:24AM +0000, Andrew Cooper wrote:
> > On 04/11/16 08:29, Luwei Kang wrote:
> > > Enable get xstate cpuid leaf information regarding avx512 in guest.
> > >
> > > Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
> > 
> > Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > 
> 
> Oops, should have read all the entire thread.
> 
> I think we can sneak this in for 4.8 if we have some free cycles,
> otherwise I will queue it up for -next.

It would be good to get it in as it provides some nice performance
benefits for guests.

> 
> > > ---
> > >  tools/libxc/xc_cpuid_x86.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c
> > > index de06b32..d761805 100644
> > > --- a/tools/libxc/xc_cpuid_x86.c
> > > +++ b/tools/libxc/xc_cpuid_x86.c
> > > @@ -406,6 +406,9 @@ static void intel_xc_cpuid_policy(xc_interface *xch,
> > >  #define X86_XCR0_AVX    (1ULL <<  2)
> > >  #define X86_XCR0_BNDREG (1ULL <<  3)
> > >  #define X86_XCR0_BNDCSR (1ULL <<  4)
> > > +#define X86_XCR0_OPMASK (1ULL <<  5)
> > > +#define X86_XCR0_ZMM    (1ULL <<  6)
> > > +#define X86_XCR0_HI_ZMM (1ULL <<  7)
> > >  #define X86_XCR0_PKRU   (1ULL <<  9)
> > >  #define X86_XCR0_LWP    (1ULL << 62)
> > >  
> > > @@ -437,6 +440,9 @@ static void xc_cpuid_config_xsave(xc_interface *xch,
> > >      if ( test_bit(X86_FEATURE_MPX, info->featureset) )
> > >          guest_xfeature_mask |= X86_XCR0_BNDREG | X86_XCR0_BNDCSR;
> > >  
> > > +    if ( test_bit(X86_FEATURE_AVX512F, info->featureset) )
> > > +        guest_xfeature_mask |= X86_XCR0_OPMASK | X86_XCR0_ZMM | 
> > > X86_XCR0_HI_ZMM;
> > > +
> > >      if ( test_bit(X86_FEATURE_PKU, info->featureset) )
> > >          guest_xfeature_mask |= X86_XCR0_PKRU;
> > >  
> > 
> 
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