Specification says that AVX instruction will generate #UD exception if
XCR0 is not set up appropriately.
Which is indeed what happens, and that's the bug in OpenSSL we were
trying to fix. OpenSSL assumed (against the spec) that XSAVE=0 implies
AVX=0, and didn't check whether AVX needed
commit 6c3f6041172b78d5532c6bf3680d304e92ec2e66
Author: Sheng Yang sh...@linux.intel.com
Date: Tue Jun 22 13:49:21 2010 +0800
KVM: x86: Enable AVX for guest
Enable Intel(R) Advanced Vector Extension(AVX) for guest.
The detection of AVX feature includes OSXSAVE bit
On Fri, 2011-11-18 at 12:16 +0100, Andy Polyakov via RT wrote:
commit 6c3f6041172b78d5532c6bf3680d304e92ec2e66
Author: Sheng Yang sh...@linux.intel.com
Date: Tue Jun 22 13:49:21 2010 +0800
KVM: x86: Enable AVX for guest
Enable Intel(R) Advanced Vector Extension(AVX) for
On Tue, 2011-11-08 at 22:29 +0100, Andy Polyakov via RT wrote:
As for XEN, if it in fact masks XSAVE, but not AVX bits, than even
check for XSAVE bit should 'jnc (label(clear_avx));' instead of
done. As well as that x86_64cpuid.pl should test for XSAVE...
That would also work, but it's
On 11/08/2011 08:32 PM, Andy Polyakov via RT wrote:
No, the test is bypassed if XSAVE is 0, not 1. XSAVE being 0 also
implies that AVX flag [as well as FMA and XOP] is 0, which is why is
jumps to 'done' and not 'clear_avx'.
This assertion is unfortunately not true on RHEL-6 guests on AVX
On 11/07/2011 07:08 PM, Andy Polyakov via RT wrote:
No, the test is bypassed if XSAVE is 0, not 1. XSAVE being 0 also
implies that AVX flag [as well as FMA and XOP] is 0, which is why is
jumps to 'done' and not 'clear_avx'.
This assertion is unfortunately not true on RHEL-6 guests on AVX
No, the test is bypassed if XSAVE is 0, not 1. XSAVE being 0 also
implies that AVX flag [as well as FMA and XOP] is 0, which is why is
jumps to 'done' and not 'clear_avx'.
This assertion is unfortunately not true on RHEL-6 guests on AVX capable
CPUs in XEN VM.
Could you spell it for me?
On Tue, 2011-11-08 at 20:32 +0100, Andy Polyakov via RT wrote:
As for XEN, if it in fact masks XSAVE, but not AVX bits, than even
check for XSAVE bit should 'jnc (label(clear_avx));' instead of
done. As well as that x86_64cpuid.pl should test for XSAVE...
That would also work, but it's
As for XEN, if it in fact masks XSAVE, but not AVX bits, than even
check for XSAVE bit should 'jnc (label(clear_avx));' instead of
done. As well as that x86_64cpuid.pl should test for XSAVE...
That would also work, but it's useless because the spec OTOH says that
you *can* ignore XSAVE (and
Hi Andy,
On 11/07/2011 08:23 AM, Tomas Mraz via RT wrote:
No, the test is bypassed if XSAVE is 0, not 1. XSAVE being 0 also
implies that AVX flag [as well as FMA and XOP] is 0, which is why is
jumps to 'done' and not 'clear_avx'.
This assertion is unfortunately not true on RHEL-6 guests on
Hi Andy,
On 11/07/2011 08:23 AM, Tomas Mraz via RT wrote:
No, the test is bypassed if XSAVE is 0, not 1. XSAVE being 0 also
implies that AVX flag [as well as FMA and XOP] is 0, which is why is
jumps to 'done' and not 'clear_avx'.
This assertion is unfortunately not true on RHEL-6 guests
No, the test is bypassed if XSAVE is 0, not 1. XSAVE being 0 also
implies that AVX flag [as well as FMA and XOP] is 0, which is why is
jumps to 'done' and not 'clear_avx'.
This assertion is unfortunately not true on RHEL-6 guests on AVX capable
CPUs in XEN VM.
Could you spell it for me?
On Sat, 2011-11-05 at 11:53 +0100, Andy Polyakov via RT wrote:
x86cpuid.pl instead is completely broken:
- the whole test is bypassed if XSAVE=1, which makes absolutely no sense.
x86_64cpuid.pl is right in testing OSXSAVE
No, the test is bypassed if XSAVE is 0, not 1. XSAVE being 0
Here is analysis by Paolo Bonzini:
I compared crypto/x86_64cpuid.pl and crypto/x86cpuid.pl, and the code in the
latter is wrong.
From x86_64cpuid.pl:
mov %edx,%r10d # %r9d:%r10d is copy of %ecx:%edx
bt \$27,%r9d # check OSXSAVE bit
Here is analysis by Paolo Bonzini:
I compared crypto/x86_64cpuid.pl and crypto/x86cpuid.pl, and the code in the
latter is wrong.
From x86_64cpuid.pl:
mov %edx,%r10d # %r9d:%r10d is copy of %ecx:%edx
bt \$27,%r9d # check OSXSAVE bit
jnc
15 matches
Mail list logo
