[PATCH 3/3 v2] XSAVE/XRSTOR: enable guest AVX

[PATCH 3/3 v2] XSAVE/XRSTOR: enable guest AVX

[Han, Weidong]

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This patch enables Intel(R) Advanced Vector Extension (AVX) for guest.

Signed-off-by: Weidong Han <weidong.han@intel.com>

[-- Attachment #2: guest-avx.patch --]
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diff -r fc6e0522a6a7 tools/libxc/xc_cpufeature.h
--- a/tools/libxc/xc_cpufeature.h	Fri Aug 27 08:00:07 2010 -0400
+++ b/tools/libxc/xc_cpufeature.h	Fri Aug 27 08:01:13 2010 -0400
@@ -101,6 +101,7 @@
 #define X86_FEATURE_POPCNT	(4*32+23) /* POPCNT instruction */
 #define X86_FEATURE_AES		(4*32+25) /* AES acceleration instructions */
 #define X86_FEATURE_XSAVE	(4*32+26) /* XSAVE/XRSTOR/XSETBV/XGETBV */
+#define X86_FEATURE_AVX		(4*32+28) /* Advanced Vector Extensions */
 #define X86_FEATURE_HYPERVISOR	(4*32+31) /* Running under some hypervisor */
 
 /* VIA/Cyrix/Centaur-defined CPU features, CPUID level 0xC0000001, word 5 */
diff -r fc6e0522a6a7 tools/libxc/xc_cpuid_x86.c
--- a/tools/libxc/xc_cpuid_x86.c	Fri Aug 27 08:00:07 2010 -0400
+++ b/tools/libxc/xc_cpuid_x86.c	Fri Aug 27 08:01:13 2010 -0400
@@ -195,7 +195,8 @@ static void xc_cpuid_hvm_policy(
                     bitmaskof(X86_FEATURE_SSE4_1) |
                     bitmaskof(X86_FEATURE_SSE4_2) |
                     bitmaskof(X86_FEATURE_POPCNT) |
-                    bitmaskof(X86_FEATURE_AES));
+                    bitmaskof(X86_FEATURE_AES) |
+                    bitmaskof(X86_FEATURE_AVX));
 
         regs[2] |= bitmaskof(X86_FEATURE_HYPERVISOR);
 

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Re: [PATCH 3/3 v2] XSAVE/XRSTOR: enable guest AVX

[Konrad Rzeszutek Wilk]

On Tue, Aug 31, 2010 at 10:52:38PM +0800, Han, Weidong wrote:
> This patch enables Intel(R) Advanced Vector Extension (AVX) for guest.

I thought that this would also work on the AMD Bulldozer's CPUs? Or is the
Intel AVX incompatible with AMD AVX?

> 
> Signed-off-by: Weidong Han <weidong.han@intel.com>


> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: [PATCH 3/3 v2] XSAVE/XRSTOR: enable guest AVX

[Li, Xin]

> On Tue, Aug 31, 2010 at 10:52:38PM +0800, Han, Weidong wrote:
> > This patch enables Intel(R) Advanced Vector Extension (AVX) for guest.
> 
> I thought that this would also work on the AMD Bulldozer's CPUs? Or is the
> Intel AVX incompatible with AMD AVX?

The code just checks if a feature is available thru CPUID before using, no matter it's Intel CPU or AMD.

There are 2 approaches to provide a new feature, use a compatible way the other side is using thus reuse the code/binary, or a complete new way.  There are many examples you can find in Linux/Xen code.

AMD people can comment if they will implement the AVX like feature.  If yes, if it's in a software compatible way or totally new.

Thanks!
-Xin

RE: [PATCH 3/3 v2] XSAVE/XRSTOR: enable guest AVX

[Huang2, Wei]

The AVX feature bit is compatible between Intel and AMD. AMD has another XSAVE/XRSTOR related feature (light-weight profiling) to be added in Xen. We are going to provide patches when they are ready.

-Wei
-----Original Message-----
From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of Li, Xin
Sent: Wednesday, September 01, 2010 9:23 AM
To: Konrad Rzeszutek Wilk; Han, Weidong
Cc: Xen-devel; Keir Fraser; Jan Beulich
Subject: RE: [Xen-devel] [PATCH 3/3 v2] XSAVE/XRSTOR: enable guest AVX

> On Tue, Aug 31, 2010 at 10:52:38PM +0800, Han, Weidong wrote:
> > This patch enables Intel(R) Advanced Vector Extension (AVX) for guest.
> 
> I thought that this would also work on the AMD Bulldozer's CPUs? Or is the
> Intel AVX incompatible with AMD AVX?

The code just checks if a feature is available thru CPUID before using, no matter it's Intel CPU or AMD.

There are 2 approaches to provide a new feature, use a compatible way the other side is using thus reuse the code/binary, or a complete new way.  There are many examples you can find in Linux/Xen code.

AMD people can comment if they will implement the AVX like feature.  If yes, if it's in a software compatible way or totally new.

Thanks!
-Xin

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