From: Borislav Petkov <bp@alien8.de>
To: Saurabh Sengar <ssengar@linux.microsoft.com>
Cc: ssengar@microsoft.com, mikelley@microsoft.com,
tglx@linutronix.de, mingo@redhat.com,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
peterz@infradead.org, tim.c.chen@linux.intel.com,
will@kernel.org, song.bao.hua@hisilicon.com,
suravee.suthikulpanit@amd.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/cacheinfo: Don't use cpu_llc_shared_map for !CONFIG_SMP
Date: Wed, 17 Aug 2022 21:40:29 +0200 [thread overview]
Message-ID: <Yv1ELaWHbRfvdt/p@zn.tnic> (raw)
In-Reply-To: <1660148115-302-1-git-send-email-ssengar@linux.microsoft.com>
On Wed, Aug 10, 2022 at 09:15:15AM -0700, Saurabh Sengar wrote:
> cpu_llc_shared_map is always declared and defined, but populated in
> arch/x86/kernel/smpboot.c which only builds for CONFIG_SMP=y. For
> UniProcessor builds this mask is never populated and hence invalid.
> Current code doesn't handle the case of AMD UniProcessor correctly,
What is "AMD UniProcessor"?
> which results "shared_cpu_map" and "shared_cpu_list" files missing from
> sysfs entries for l3 cache. This patch fixes this issue.
What issue exactly?
What is the real life use case for this?
> This code used to work because of a another bug in 'cpumask_next',
> where in the CONFIG_SMP=n case the cpumask_next() ignores empty mask
> that results as if CPU 0 was set. This bug in 'cpumask_next' was fixed by
> following commit, which exposes the cpu_llc_shared_map bug.
>
> b81dce77ced ("cpumask: Fix invalid uniprocessor mask assumption")
>
> Fixes: 2b83809a5e ("x86/cpu/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask")
Add
---
[core]
abbrev = 12
[alias]
one = show -s --pretty='format:%h (\"%s\")'
---
to your git .config so that when you do
$ git one <commit id>
you can get the proper formatting and abbreviated sha1 for commits.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-08-17 19:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-10 16:15 [PATCH] x86/cacheinfo: Don't use cpu_llc_shared_map for !CONFIG_SMP Saurabh Sengar
2022-08-12 14:56 ` Michael Kelley (LINUX)
2022-08-17 19:40 ` Borislav Petkov [this message]
2022-08-18 4:52 ` Saurabh Singh Sengar
2022-08-18 11:57 ` Borislav Petkov
2022-08-18 12:29 ` Saurabh Singh Sengar
2022-08-19 17:16 ` Borislav Petkov
2022-08-19 17:46 ` Saurabh Singh Sengar
2022-08-20 8:39 ` [PATCH] x86/cacheinfo: Add a cpu_llc_shared_mask() UP variant Borislav Petkov
2022-09-29 9:04 ` [tip: x86/urgent] " tip-bot2 for Borislav Petkov
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