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AHgh+RrVL1fOqxL9zk4L5qLma3HR3NEkZS9PtApFNoUYZYRlRlLSlqL7s5d7rGoRqCDysSiyVNeb2He3Va2VGWg=@vger.kernel.org X-Gm-Message-State: AOJu0YwdaNokLOZXNWgdJUF/hyAZ9wjEVvxx1ETKfFuGCZPuvGj/Owhp IdIzIfquPeV3G4e0kOzN9MYsg95/bYZonqK+1Y8q1U2J2Zlpgn7VA/Bs5TElphzWbuNqNoIcg/I 7JFl44A== X-Received: from plml3.prod.google.com ([2002:a17:903:1843:b0:2cc:7ef7:ea41]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:13c7:b0:2ce:9c48:22d3 with SMTP id d9443c01a7336-2d30033718fmr21913835ad.11.1786370191619; Mon, 10 Aug 2026 06:56:31 -0700 (PDT) Date: Mon, 10 Aug 2026 06:56:31 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260806233609.212337-14-seanjc@google.com> Message-ID: Subject: Re: [PATCH v6 13/51] x86/acrn: Mark TSC frequency as known when using ACRN for calibration From: Sean Christopherson To: David Woodhouse Cc: kas@kernel.org, rick.p.edgecombe@intel.com, pbonzini@redhat.com, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, ajay.kaher@broadcom.com, alexey.makhalov@broadcom.com, jan.kiszka@siemens.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, jgross@suse.com, daniel.lezcano@kernel.org, tglx@kernel.org, jstultz@google.com, x86@kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Content-Type: text/plain; charset="us-ascii" On Sat, Aug 08, 2026, David Woodhouse wrote: > On Thu, 2026-08-06 at 16:35 -0700, Sean Christopherson wrote: > > Mark the TSC frequency as known when using ACRN's PV CPUID information. > > Per commit 81a71f51b89e ("x86/acrn: Set up timekeeping") and common sense, > > the TSC freq is explicitly provided by the hypervisor. > > > > Signed-off-by: Sean Christopherson > > Huh... does this literally get reverted completely in the very *next* > patch in the series? Kind of weird, but I guess in some ways it makes > sense... The literal code gets reverted, but the functional change does not. Before this change, ACRN is the only guest-side PV code that doesn't set X86_FEATURE_TSC_KNOWN_FREQ when the hypervisor provides the exact frequency. I.e. this patch allows for making the "No functional change intended" claim in the next patch.