From: Maxim Levitsky <mlevitsk@redhat.com>
To: Herbert Xu <herbert@gondor.apana.org.au>, Borislav Petkov <bp@alien8.de>
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>, 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
Date: Thu, 20 Oct 2022 13:21:30 +0300 [thread overview]
Message-ID: <3cc09554f20231aecdf0cd762a282c42aee9273c.camel@redhat.com> (raw)
In-Reply-To: <Y1EPRauBmAXMVrCa@loth.rohan.me.apana.org.au>
On Thu, 2022-10-20 at 17:05 +0800, Herbert Xu wrote:
> On Thu, Oct 20, 2022 at 10:59:48AM +0200, Borislav Petkov wrote:
> > 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?!?!
>
> That's exactly what I said when this was first reported to me as
> a crypto bug :)
I agree with you, however this patch series is just refactoring/hardening of the kernel -
if the kernel can avoid crashing - why not.
Of course the hypervisor should not present such broken configurations to the guest -
in fact the guest kernel can't fix this - guest userspace will still see wrong CPUID and
can still crash.
TL;DR - this patch series is not intended to workaround a broken hypervisor and such,
it is just a hardening against misconfiguration.
Best regards,
Maxim Levitsky
>
> Cheers,
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
>
next prev parent reply other threads:[~2022-10-20 10:24 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-18 14:11 [PATCH v2 0/5] x86: cpuid: improve support for broken CPUID configurations Maxim Levitsky
2022-07-18 14:11 ` [PATCH v2 1/5] perf/x86/intel/lbr: use setup_clear_cpu_cap instead of clear_cpu_cap Maxim Levitsky
2022-09-19 14:31 ` Borislav Petkov
2022-09-20 8:20 ` Maxim Levitsky
2022-09-26 13:12 ` Borislav Petkov
2022-09-28 10:49 ` Maxim Levitsky
2022-10-20 8:59 ` Borislav Petkov
2022-10-20 9:05 ` Herbert Xu
2022-10-20 10:21 ` Maxim Levitsky [this message]
2022-10-20 11:13 ` Borislav Petkov
2022-10-22 21:08 ` H. Peter Anvin
2022-11-02 13:40 ` Paolo Bonzini
2022-11-02 14:27 ` Elliott, Robert (Servers)
2022-11-02 16:23 ` H. Peter Anvin
2022-11-02 18:19 ` H. Peter Anvin
2022-11-02 19:14 ` Elliott, Robert (Servers)
2022-11-03 13:26 ` Paolo Bonzini
2022-11-03 13:30 ` Paolo Bonzini
2022-07-18 14:11 ` [PATCH v2 2/5] x86/cpuid: refactor setup_clear_cpu_cap()/clear_cpu_cap() Maxim Levitsky
2022-10-21 16:19 ` Borislav Petkov
2022-11-07 19:10 ` Borislav Petkov
2022-11-07 21:57 ` Borislav Petkov
2022-07-18 14:11 ` [PATCH v2 3/5] x86/cpuid: move filter_cpuid_features to cpuid-deps.c Maxim Levitsky
2022-07-18 14:11 ` [PATCH v2 4/5] x86/cpuid: remove 'warn' parameter from filter_cpuid_features Maxim Levitsky
2022-07-18 14:11 ` [PATCH v2 5/5] x86/cpuid: check for dependencies violations in CPUID and attempt to fix them Maxim Levitsky
2022-07-28 7:30 ` [PATCH v2 0/5] x86: cpuid: improve support for broken CPUID configurations Maxim Levitsky
2022-08-01 16:05 ` Maxim Levitsky
2022-08-01 16:31 ` Dave Hansen
2022-08-01 16:41 ` Maxim Levitsky
2022-09-19 13:43 ` Maxim Levitsky
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