From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, H Peter Anvin <hpa@zytor.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [RFC PATCH] x86/cpufeatures: Enumerate new AVX512 bfloat16 instructions
Date: Wed, 12 Jun 2019 07:10:49 -0700 [thread overview]
Message-ID: <20190612141049.GA20308@linux.intel.com> (raw)
In-Reply-To: <20190612040259.GC32652@zn.tnic>
On Wed, Jun 12, 2019 at 06:02:59AM +0200, Borislav Petkov wrote:
> On Tue, Jun 11, 2019 at 08:32:59PM -0700, Fenghua Yu wrote:
> > Currently KVM doesn't simulate scattered features (the ones in CPUID_LNX_*
> > in cpuid_leafs) as reverse_cpuid[] doesn't contain CPUID_LNX_*.
>
> 43500e6f294d ("x86/cpufeatures: Remove get_scattered_cpuid_leaf()")
>
> > After the X86_FEATURES_CQM_* features are changed to scattered features,
> > they will not be simulated by KVM any more as CPUID_F_0_EDX and CPUID_F_1_EDX
> > are removed.
>
> Does KVM even support resctrl? I doubt only exporting a couple of CPUID
> bits into the guest is enough...
KVM doesn't support resctrl. Moving X86_FEATURES_CQM_* to a scattered
leaf won't affect KVM.
> > Should patch #1 simulate X86_FEATURE_CQM_* in KVM? Or let KVM guys handle
> > the scattered features?
>
> Right, the scattered thing was removed as KVM didn't need it,
> apparently, see above.
Let KVM people deal with it, in the unlikely event someone adds resctrl
support to KVM.
next prev parent reply other threads:[~2019-06-12 14:10 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-10 17:02 [RFC PATCH] x86/cpufeatures: Enumerate new AVX512 bfloat16 instructions Fenghua Yu
2019-06-10 19:20 ` Borislav Petkov
2019-06-11 18:19 ` Fenghua Yu
2019-06-11 19:47 ` Borislav Petkov
2019-06-11 22:28 ` Fenghua Yu
2019-06-12 3:29 ` Yu, Fenghua
2019-06-12 3:59 ` Borislav Petkov
2019-06-12 17:41 ` Fenghua Yu
2019-06-12 3:32 ` Fenghua Yu
2019-06-12 4:02 ` Borislav Petkov
2019-06-12 14:10 ` Sean Christopherson [this message]
2019-06-12 17:04 ` Fenghua Yu
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