linux-kernel - [PATCH 0/4] x86: cpuid: improve support for broken CPUID configurations

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Message-Id: <20220622144820.751402-1-mlevitsk@redhat.com>
Date:   Wed, 22 Jun 2022 17:48:16 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     "Chang S. Bae" <chang.seok.bae@...el.com>,
        Jiri Olsa <jolsa@...nel.org>, linux-perf-users@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        "David S. Miller" <davem@...emloft.net>,
        Borislav Petkov <bp@...en8.de>,
        Kees Cook <keescook@...omium.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Jane Malalane <jane.malalane@...rix.com>,
        Tony Luck <tony.luck@...el.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-crypto@...r.kernel.org (open list:CRYPTO API),
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 0/4] x86: cpuid: improve support for broken CPUID configurations

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.

Best regards,
	Maxim Levitsky

Maxim Levitsky (4):
  perf/x86/intel/lbr: use setup_clear_cpu_cap instead of clear_cpu_cap
  x86/cpuid: refactor setup_clear_cpu_cap/clear_feature
  x86/cpuid: move filter_cpuid_features to cpuid-deps.c
  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      | 50 +-----------------
 arch/x86/kernel/cpu/cpuid-deps.c  | 84 +++++++++++++++++++++++++++----
 4 files changed, 78 insertions(+), 59 deletions(-)

-- 
2.26.3