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From: "Luc, Piotr" <Piotr.Luc@intel.com>
To: "pbonzini@redhat.com" <pbonzini@redhat.com>,
	"bp@alien8.de" <bp@alien8.de>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"he.chen@linux.intel.com" <he.chen@linux.intel.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"x86@kernel.org" <x86@kernel.org>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"Kang, Luwei" <luwei.kang@intel.com>,
	"rkrcmar@redhat.com" <rkrcmar@redhat.com>
Subject: Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS features to kvm guest
Date: Mon, 31 Oct 2016 09:15:43 +0000	[thread overview]
Message-ID: <1477905033.32008.5.camel@intel.com> (raw)
In-Reply-To: <425702906.9319122.1477743677017.JavaMail.zimbra@redhat.com>

On Sat, 2016-10-29 at 08:21 -0400, Paolo Bonzini wrote:
> 
> Currently none of the bits in CPUID[7,0].edx is ever masked by the
> host, so
> this would be enough.  If we ever need to do some masking, I guess
> I'll
> practice my puss-in-boots look and submit a patch to add CPUID[7,0]
> back
> as a separate cpufeature entr.

I think that in v4.9-rc2 the CPUID[7,0].edx bits can be masked out by
applying noxsave to cmdline. Using directly cpu_count will result in
passing the bits in edx to a guest directly while the xsaveopt and rest
of AVX512 features bits will be cleared. 

Thx
Piotr

  parent reply	other threads:[~2016-10-31  9:15 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-28  9:12 [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS features to kvm guest He Chen
2016-10-28  9:31 ` Paolo Bonzini
2016-10-28  9:46   ` He Chen
2016-10-28  9:54     ` Paolo Bonzini
2016-10-28  9:55       ` He Chen
2016-10-28 10:13 ` Luc, Piotr
2016-10-28 10:17   ` Paolo Bonzini
2016-10-28 11:08     ` Borislav Petkov
2016-10-28 12:07       ` Paolo Bonzini
2016-10-28 12:21         ` Borislav Petkov
2016-10-29 12:21           ` Paolo Bonzini
2016-10-29 12:25             ` Borislav Petkov
2016-10-29 12:36               ` Paolo Bonzini
2016-10-29 12:53                 ` Borislav Petkov
2016-10-29 13:20                   ` Paolo Bonzini
2016-10-31  9:15             ` Luc, Piotr [this message]
2016-10-31  9:53               ` Borislav Petkov
2016-10-31 10:18                 ` Luc, Piotr
2016-10-31 10:30                   ` Borislav Petkov
2016-10-31 10:47                     ` Paolo Bonzini
2016-10-31 11:05                       ` Borislav Petkov
2016-10-31 11:41                         ` Paolo Bonzini
2016-11-01  7:48                           ` He Chen
2016-11-01  8:46                             ` Borislav Petkov

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