linux-kernel - Re: [PATCH v2 0/5] x86: cpuid: improve support for broken CPUID configurations

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Date:   Mon, 01 Aug 2022 19:05:29 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>,
        "David S. Miller" <davem@...emloft.net>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Jane Malalane <jane.malalane@...rix.com>,
        Kees Cook <keescook@...omium.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Jiri Olsa <jolsa@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-perf-users@...r.kernel.org,
        "open list:CRYPTO API" <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH v2 0/5] x86: cpuid: improve support for broken CPUID
 configurations

On Thu, 2022-07-28 at 10:30 +0300, Maxim Levitsky wrote:
> 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.

Another kind ping on these patches.


Best regards,
	Maxim Levitsky
> 
> Best regards,
> 	Maxim Levitsky