linux-kernel - Re: [PATCH v3 09/14] x86/svm: Deflake svm_tsc_scale

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Message-ID: <aRZ5G6GSMnbHxx_K@google.com>
Date: Thu, 13 Nov 2025 16:34:35 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Kevin Cheng <chengkev@...gle.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/14] x86/svm: Deflake svm_tsc_scale_test

On Mon, Nov 10, 2025, Yosry Ahmed wrote:
> On an AMT Turin (EPYC Zen 5), svm_tsc_scale_test flakes on the last test
> case with 0.0001 TSC scaling ratio, even with the 24-bit shift for
> stability. On failure, the actual value is 49 instead of the expected
> 50.
> 
> Use a higher scaling ratio, 0.001, which makes the test pass
> consistently.

Top-tier analysis right here :-D

I'm going to take Jim's version instead of papering over the bug.

https://lore.kernel.org/all/CALMp9eQep3H-OtqmLe3O2MsOT-Vx4y0-LordKgN+pkp04VLSWw@mail.gmail.com