From: Ingo Molnar <mingo@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Sandipan Das <sandipan.das@amd.com>,
linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
x86@kernel.org
Subject: Re: [tip: perf/urgent] x86/cpufeatures: Add dedicated feature word for CPUID leaf 0x80000022[EAX]
Date: Tue, 19 Mar 2024 14:05:31 +0100 [thread overview]
Message-ID: <ZfmNmzuCDaTJO3jC@gmail.com> (raw)
In-Reply-To: <20240319130054.GCZfmMhp-7Qa0eDaTC@fat_crate.local>
* Borislav Petkov <bp@alien8.de> wrote:
> On Tue, Mar 19, 2024 at 10:36:01AM -0000, tip-bot2 for Sandipan Das wrote:
> > The following commit has been merged into the perf/urgent branch of tip:
> >
> > Commit-ID: f0a22ea644717fa21698a32d342fcd307e53a935
> > Gitweb: https://git.kernel.org/tip/f0a22ea644717fa21698a32d342fcd307e53a935
> > Author: Sandipan Das <sandipan.das@amd.com>
> > AuthorDate: Tue, 19 Mar 2024 13:48:16 +05:30
> > Committer: Ingo Molnar <mingo@kernel.org>
> > CommitterDate: Tue, 19 Mar 2024 11:23:47 +01:00
> >
> > x86/cpufeatures: Add dedicated feature word for CPUID leaf 0x80000022[EAX]
> >
> > Move the existing scattered performance monitoring related feature bits
> > from CPUID leaf 0x80000022[EAX] into a dedicated word since additional
> > bits will be defined from the same leaf in the future. This includes
> > X86_FEATURE_PERFMON_V2 and X86_FEATURE_AMD_LBR_V2.
>
> That CPUID leaf has a whopping three bits defined and the rest is
> reserved. You should do a dedicated leaf when we use at least 50% of the
> bits in the leaf. But not like this.
>
> Please do simply another synthetic leaf and put your bits there.
Yeah, that was my original suggestion too, so fully agreed - I got
distracted by the cleanup factor, but it's not worth spreading out the
cpuinfo.x86_capability[] bits unnecessarily.
Thanks,
Ingo
prev parent reply other threads:[~2024-03-19 13:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-19 10:36 [tip: perf/urgent] x86/cpufeatures: Add dedicated feature word for CPUID leaf 0x80000022[EAX] tip-bot2 for Sandipan Das
2024-03-19 13:00 ` Borislav Petkov
2024-03-19 13:05 ` Ingo Molnar [this message]
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