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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.

      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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