Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 20 Oct 2022 10:59:48 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Maxim Levitsky <mlevitsk@redhat.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Tony Luck <tony.luck@intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "Chang S. Bae" <chang.seok.bae@intel.com>,
        Jane Malalane <jane.malalane@citrix.com>,
        Kees Cook <keescook@chromium.org>,
        Kan Liang <kan.liang@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Jiri Olsa <jolsa@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        linux-perf-users@vger.kernel.org,
        "open list:CRYPTO API" <linux-crypto@vger.kernel.org>
Subject: Re: [PATCH v2 1/5] perf/x86/intel/lbr: use setup_clear_cpu_cap
 instead of clear_cpu_cap
Message-ID: <Y1EOBAaLbv2CXBDL@zn.tnic>
References: <20220718141123.136106-1-mlevitsk@redhat.com>
 <20220718141123.136106-2-mlevitsk@redhat.com>
 <Yyh9RDbaRqUR1XSW@zn.tnic>
 <c105971a72dfe6d46ad75fb7e71f79ba716e081c.camel@redhat.com>
 <YzGlQBkCSJxY+8Jf@zn.tnic>
 <c1168e8bd9077a2cc9ef61ee06db7a4e8c0f1600.camel@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <c1168e8bd9077a2cc9ef61ee06db7a4e8c0f1600.camel@redhat.com>
Precedence: bulk

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).

I really really don't like it when people are fixing the wrong thing.

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.

Some of your other bits look sensible and I'd take a deeper look but
this does not make any sense. This is a hypervisor problem - not a
kernel one.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette