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Date:   Sat, 22 Oct 2022 14:08:37 -0700
From:   "H. Peter Anvin" <hpa@zytor.com>
To:     Borislav Petkov <bp@alien8.de>,
        Maxim Levitsky <mlevitsk@redhat.com>
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Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_v2_1/5=5D_perf/x86/intel/lbr=3A_use_?= =?US-ASCII?Q?setup=5Fclear=5Fcpu=5Fcap_instead_of_clear=5Fcpu=5Fcap?=
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On October 20, 2022 1:59:48 AM PDT, Borislav Petkov <bp@alien8=2Ede> wrote:
>On Wed, Sep 28, 2022 at 01:49:34PM +0300, Maxim Levitsky wrote:
>> Patch 5 is the main fix - it makes the kernel to be tolerant to a
>> broken CPUID config (coming hopefully from hypervisor), where you have
>> a feature (AVX2 in my case) but not a feature on which this feature
>> depends (AVX)=2E
>
>I really really don't like it when people are fixing the wrong thing=2E
>
>Why does the kernel need to get fixed when something else can't get its
>CPUID dependencies straight? I don't even want to know why something
>would set AVX2 without AVX?!?!
>
>Srsly=2E
>
>Some of your other bits look sensible and I'd take a deeper look but
>this does not make any sense=2E This is a hypervisor problem - not a
>kernel one=2E
>
>Thx=2E
>

Yes, this is utterly nonsensical and it will break user space applications=
 left, right, and center=2E