Re: [Xen-devel] [PATCH V3 4/6] libxc: expose xsaves/xgetbv1/xsavec to hvm guest

[Shuai Ruan <shuai.ruan@xxxxxxxxxxxxxxx>]

On Wed, Aug 05, 2015 at 09:37:22AM +0100, Ian Campbell wrote:
> On Wed, 2015-08-05 at 09:57 +0800, Shuai Ruan wrote:
> > This patch exposes xsaves/xgetbv1/xsavec to hvm guest.
> > The reserved bits of eax/ebx/ecx/edx must be cleaned up
> > when call cpuid(0dh) with leaf 1 or 2..63.
> > 
> > According to the spec the following bits must be reseved:
> 
> "reserved"
> 
Sorry,:)
> > For leaf 1, bits 03-04/08-31 of ecx is reserved. Edx is reserved.
> > For leaf 2...63, bits 01-31 of ecx is reserved. Edx is reserved.
> > 
> > Signed-off-by: Shuai Ruan <shuai.ruan@xxxxxxxxxxxxxxx>
> 
> Although this is toolstack code I think this really ought to be acked by
> the hypervisor x86 maintainers, if they are happy with it then I am too,
> and in that case you may add:
> 
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> 
Ok.Thanks for your review, Ian.
> > ---
> >  tools/libxc/xc_cpuid_x86.c | 13 +++++++++----
> >  1 file changed, 9 insertions(+), 4 deletions(-)
> > 
> > diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c
> > index c97f91a..b69676a 100644
> > --- a/tools/libxc/xc_cpuid_x86.c
> > +++ b/tools/libxc/xc_cpuid_x86.c
> > @@ -211,6 +211,9 @@ static void intel_xc_cpuid_policy(
> >  }
> >  
> >  #define XSAVEOPT        (1 << 0)
> > +#define XSAVEC          (1 << 1)
> > +#define XGETBV1         (1 << 2)
> > +#define XSAVES          (1 << 3)
> >  /* Configure extended state enumeration leaves (0x0000000D for xsave) */
> >  static void xc_cpuid_config_xsave(
> >      xc_interface *xch, domid_t domid, uint64_t xfeature_mask,
> > @@ -247,8 +250,9 @@ static void xc_cpuid_config_xsave(
> >          regs[1] = 512 + 64; /* FP/SSE + XSAVE.HEADER */
> >          break;
> >      case 1: /* leaf 1 */
> > -        regs[0] &= XSAVEOPT;
> > -        regs[1] = regs[2] = regs[3] = 0;
> > +        regs[0] &= (XSAVEOPT | XSAVEC | XGETBV1 | XSAVES);
> > +        regs[2] &= 0xe7;
> > +        regs[3] = 0;
> >          break;
> >      case 2 ... 63: /* sub-leaves */
> >          if ( !(xfeature_mask & (1ULL << input[1])) )
> > @@ -256,8 +260,9 @@ static void xc_cpuid_config_xsave(
> >              regs[0] = regs[1] = regs[2] = regs[3] = 0;
> >              break;
> >          }
> > -        /* Don't touch EAX, EBX. Also cleanup ECX and EDX */
> > -        regs[2] = regs[3] = 0;
> > +        /* Don't touch EAX, EBX. Also cleanup EDX. Cleanup bits 01-32 of 
> > ECX*/
> > +        regs[2] &= 0x1;
> > +        regs[3] = 0;
> >          break;
> >      }
> >  }
> 
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