From: Peter Zijlstra <peterz@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andreas Mohr <andi@lisas.de>,
K Prateek Nayak <kprateek.nayak@amd.com>,
linux-kernel@vger.kernel.org, rafael@kernel.org, lenb@kernel.org,
linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org,
dave.hansen@linux.intel.com, bp@alien8.de, tglx@linutronix.de,
puwen@hygon.cn, mario.limonciello@amd.com, rui.zhang@intel.com,
gpiccoli@igalia.com, daniel.lezcano@linaro.org,
ananth.narayan@amd.com, gautham.shenoy@amd.com,
Calvin Ong <calvin.ong@amd.com>,
stable@vger.kernel.org, regressions@lists.linux.dev
Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture
Date: Fri, 23 Sep 2022 09:57:51 +0200 [thread overview]
Message-ID: <Yy1m/5topydhbWS2@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <4d61b9c0-ee00-c5f6-bef1-622b80c79714@intel.com>
On Thu, Sep 22, 2022 at 02:21:31PM -0700, Dave Hansen wrote:
> FWIW, I'd much rather do something like
>
> if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
> (boot_cpu_data.x86_model >= 0xF))
> return;
>
> inl(slow_whatever);
>
> than a Zen check. AMD has, as far as I know, been a lot more sequential
> and sane about model numbers than Intel, and there are some AMD model
> number range checks in the codebase today.
Some might be broken; apparently their SoC/Entertainment divisions has a
few out of order SKUs that were not listed in their regular documents.
(yay interweb)
I ran into this when I tried doing a Zen2 range check for retbleed. In
the end we ended up using the availablility of STIBP as a heuristic to
indentify Zen2+ or something.
prev parent reply other threads:[~2022-09-23 7:58 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 6:36 [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture K Prateek Nayak
2022-09-21 8:47 ` Borislav Petkov
2022-09-21 10:39 ` K Prateek Nayak
2022-09-21 13:10 ` Borislav Petkov
2022-09-21 14:15 ` Dave Hansen
2022-09-21 19:51 ` Borislav Petkov
2022-09-21 19:55 ` Limonciello, Mario
2022-09-22 3:58 ` Ananth Narayan
2022-09-22 5:44 ` K Prateek Nayak
[not found] ` <20220923160106.9297-1-ermorton@ericmoronsm1mbp.amd.com>
2022-09-23 16:15 ` Ananth Narayan
2022-09-21 15:00 ` Peter Zijlstra
2022-09-21 19:48 ` Borislav Petkov
2022-09-22 8:17 ` Peter Zijlstra
2022-09-22 15:21 ` Rafael J. Wysocki
2022-09-22 15:36 ` Borislav Petkov
2022-09-22 15:53 ` Rafael J. Wysocki
2022-09-22 16:36 ` Dave Hansen
2022-09-22 16:44 ` Dave Hansen
2022-09-22 16:54 ` K Prateek Nayak
2022-09-22 17:01 ` Dave Hansen
2022-09-22 17:48 ` Limonciello, Mario
2022-09-22 18:17 ` Dave Hansen
2022-09-22 18:28 ` Limonciello, Mario
2022-09-23 11:47 ` Ananth Narayan
2022-09-22 19:42 ` Andreas Mohr
2022-09-22 20:10 ` Andreas Mohr
2022-09-22 21:21 ` Dave Hansen
2022-09-22 21:38 ` Limonciello, Mario
2022-09-23 7:42 ` Peter Zijlstra
2022-09-23 7:57 ` Peter Zijlstra [this message]
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