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[91.219.240.8]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3749ee9ba8esm16721895f8f.50.2024.09.04.04.47.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Sep 2024 04:47:03 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Yan Zhao , Gerd Hoffmann , Paolo Bonzini , kvm@vger.kernel.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Kevin Tian , Yiwei Zhang , Lai Jiangshan , "Paul E. McKenney" , Josh Triplett Subject: Re: [PATCH 5/5] KVM: VMX: Always honor guest PAT on CPUs that support self-snoop In-Reply-To: <87frqgu2t0.fsf@redhat.com> References: <20240309010929.1403984-1-seanjc@google.com> <20240309010929.1403984-6-seanjc@google.com> <877cbyuzdn.fsf@redhat.com> <871q26unq8.fsf@redhat.com> <87jzfutmfc.fsf@redhat.com> <87frqgu2t0.fsf@redhat.com> Date: Wed, 04 Sep 2024 13:47:02 +0200 Message-ID: <87a5gntzd5.fsf@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Vitaly Kuznetsov writes: > Sean Christopherson writes: > >> On Mon, Sep 02, 2024, Vitaly Kuznetsov wrote: >>> FWIW, I use QEMU-9.0 from the same C10S (qemu-kvm-9.0.0-7.el10.x86_64) >>> but I don't think it matters in this case. My CPU is "Intel(R) Xeon(R) >>> Silver 4410Y". >> >> Has this been reproduced on any other hardware besides SPR? I.e. did we stumble >> on another hardware issue? > > Very possible, as according to Yan Zhao this doesn't reproduce on at > least "Coffee Lake-S". Let me try to grab some random hardware around > and I'll be back with my observations. We have some interesting results :-) In addition to Sapphire Rapids, the issue also reproduces on a Cascade lake CPU (Intel(R) Xeon(R) Silver 4214 CPU) but does NOT reproduce on Skylake (Intel(R) Xeon(R) Gold 5118 CPU). I don't have a lot of desktop CPUs around, so can't say much. AMD also doesn't seem to be affected, at leats AMD EPYC 7413 works fine. -- Vitaly