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Subject: Re: [PATCH v2 0/5] x86: cpuid: improve support for broken CPUID
 configurations
From:   Maxim Levitsky <mlevitsk@redhat.com>
To:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     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>,
        Borislav Petkov <bp@alien8.de>,
        "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>
Date:   Thu, 28 Jul 2022 10:30:33 +0300
In-Reply-To: <20220718141123.136106-1-mlevitsk@redhat.com>
References: <20220718141123.136106-1-mlevitsk@redhat.com>
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On Mon, 2022-07-18 at 17:11 +0300, Maxim Levitsky wrote:
> This patch series aims to harden the cpuid code against the case when
> the hypervisor exposes a broken CPUID configuration to the guest,
> in the form of having a feature disabled but not features that depend on it.
> 
> This is the more generic way to fix kernel panic in aes-ni kernel driver,
> which was triggered by CPUID configuration in which AVX is disabled but
> not AVX2.
> 
> https://lore.kernel.org/all/20211103145231.GA4485@gondor.apana.org.au/T/
> 
> This was tested by booting a guest with AVX disabled and not AVX2,
> and observing that both a warning is now printed in dmesg, and
> that avx2 is gone from /proc/cpuinfo.
> 
> V2:
> 
> I hopefully addressed all the (very good) review feedback.
> 
> Best regards,
> 	Maxim Levitsky
> 
> Maxim Levitsky (5):
>   perf/x86/intel/lbr: use setup_clear_cpu_cap instead of clear_cpu_cap
>   x86/cpuid: refactor setup_clear_cpu_cap()/clear_cpu_cap()
>   x86/cpuid: move filter_cpuid_features to cpuid-deps.c
>   x86/cpuid: remove 'warn' parameter from filter_cpuid_features
>   x86/cpuid: check for dependencies violations in CPUID and attempt to
>     fix them
> 
>  arch/x86/events/intel/lbr.c       |  2 +-
>  arch/x86/include/asm/cpufeature.h |  1 +
>  arch/x86/kernel/cpu/common.c      | 51 +-------------------
>  arch/x86/kernel/cpu/cpuid-deps.c  | 80 +++++++++++++++++++++++++++----
>  4 files changed, 74 insertions(+), 60 deletions(-)
> 
> -- 
> 2.34.3
> 
> 
A very kind ping on these patches.

Best regards,
	Maxim Levitsky