From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A60374D2EF0 for ; Wed, 1 Jul 2026 19:32:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934356; cv=none; b=CWBA268Fe40fD3UEVYofyvqOEKLE+zh0y/Gp5J//0Fr6WJhWVmlI7cgReHVVnp1yVwNWWePndX0j/kE+sBbiVXUJ7EkonJ9FXIIW6/5QPKAhtoSeHd2OnpqXeqtXwIA/v3wFi9M/GwYwppCU/pnepizlXPbUYHQQ2mK/lkKl2IA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934356; c=relaxed/simple; bh=p5tLZkB3crC07vF32aPnSFAmwAQDDSFCr6tkFys+CMo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=HNCO9kgA8MMqGzH+NXTNA/Ij3g7UpPY+ybN9cG46P49iHyRnSpeZj9XQNG5ZI+v9LApmTiQsDdoYLyWgKjJSpQ6nAyWvrnrzshqkY8CGL9viuuGCfa6kciwfXjcG6G1aLMKjuZH3q2HGYUGtSKCJ30P35vgGrWsv2WKmpa3FafE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=KOZIE8cC; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="KOZIE8cC" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2c825562f8bso11895615ad.2 for ; Wed, 01 Jul 2026 12:32:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1782934354; x=1783539154; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=evwxLM71EsC76xUKnJUsM6sZDhf4kmGP6xo/jdNLobw=; b=KOZIE8cCnD+asX9uEOP6Tky6tmu957Tt+OYf7DkxYLsGTmvHaLBldQGkcHPBJs+Wqy wNs1NCD1p2ni9DPDLK6rgpfcFBXZiGBsUAX68VHtW/gNwDahOEJntjkudfcsoPlGFXMj d35Iktse0dzYl+rHvsRha4+YogPZWoTDzJcqkhqIpiM/FFRTr2Bsghfrx1iQtZCiV2rz 8blYC+s5ksXsh8AJ3FPpZ+WWBWFMzZNnzuR+I2juRx/2BKFw+tLCuvEiI08O6Ujah0L0 orCINb52PV4U5AoTXdgVjtMceAEG68BwlfrZQDd7EOMNOi8H86HMBGQSDiFj1O+jjt56 5Zig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782934354; x=1783539154; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=evwxLM71EsC76xUKnJUsM6sZDhf4kmGP6xo/jdNLobw=; b=LtPpYdprao3QDs1xuVBIpEnpGozhT7N4FK6osYk4x+aqsw4SjyKiGlPBt42UW7V6PR 8XlGHcCEn0JXrOCHsUEuASGjGhAAq8sLKWR8fyxoiOWhn5UX9q4qG/pas9BHZ6uX7c65 qB7yqqiKo7yhyM3L4U7TBTFa/q9T6dvEue/F4kFnqg08NtCPGsQycbmZRXctfHLEGNdl zXpKb9tmPZj2pEgvE+IdRrewiGyV85aY0DJCHIg//gZOawASJb8SEcFvTsVz95/fi3kW VU+FXkajAO5+/UcmPKbVI2n2+YAi8hSnCK3Nox1nucPae29kAo0GHVtfqp46v1fzvs5n sVFA== X-Forwarded-Encrypted: i=1; AHgh+RoIqvIPhE6v29orFrTiyjfOWsh/uIsRetR3X5GyAbuTyHrXRTid0PG/o8up6+znZLbtBZMCI2KiR6AL@lists.linux.dev X-Gm-Message-State: AOJu0YwP5K1AofL5BGhGok/3hrudMPJNQZgeroP5X9RG7SKQ72zZlPfp tMQJxpZpkxMTS+gt/Jz9YHaRTDnIB0k5+qHQxP13W88eVVLSbIyfQnCrCUyFF8m/RhWihMo86hI zm9w1iA== X-Received: from plha8.prod.google.com ([2002:a17:902:ecc8:b0:2c6:a75b:2129]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:f8c:b0:2c7:d603:117f with SMTP id d9443c01a7336-2ca7e754b82mr34808385ad.26.1782934353608; Wed, 01 Jul 2026 12:32:33 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 1 Jul 2026 12:31:27 -0700 In-Reply-To: <20260701193212.749551-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260701193212.749551-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.rc0.799.gd6f94ed593-goog Message-ID: <20260701193212.749551-7-seanjc@google.com> Subject: [PATCH v5 06/51] x86/sev: Don't override CPU frequency calibration for SNP's Secure TSC From: Sean Christopherson To: Jonathan Corbet , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , Rick Edgecombe , Sean Christopherson , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Ajay Kaher , Alexey Makhalov , Jan Kiszka , Andy Lutomirski , Peter Zijlstra , Juergen Gross , Daniel Lezcano , John Stultz Cc: Shuah Khan , "H. Peter Anvin" , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , linux-doc@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, xen-devel@lists.xenproject.org, Tom Lendacky , Nikunj A Dadhania , David Woodhouse , David Woodhouse , Michael Kelley , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" Don't override the kernel's CPU frequency calibration routine when registering SNP's Secure TSC calibration routine. SNP (the architecture) provides zero guarantees that the CPU runs at the same frequency as the TSC. The justification for clobbering the CPU routine was: Since the difference between CPU base and TSC frequency does not apply in this case, the same callback is being used. but that's simply not true. E.g. if APERF/MPERF is exposed to the VM, then the CPU frequency absolutely does matter. While relying on heuristics and/or the untrusted hypervisor to provide the CPU frequency isn't ideal, it's at least not outright wrong. Fixes: 73bbf3b0fbba ("x86/tsc: Init the TSC for Secure TSC guests") Cc: Nikunj A Dadhania Cc: Tom Lendacky Signed-off-by: Sean Christopherson --- arch/x86/coco/sev/core.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index ed0ac52a765e..665de1aea0ee 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -2046,7 +2046,6 @@ void __init snp_secure_tsc_init(void) snp_tsc_freq_khz = SNP_SCALE_TSC_FREQ(tsc_freq_mhz * 1000, secrets->tsc_factor); - x86_platform.calibrate_cpu = securetsc_get_tsc_khz; x86_platform.calibrate_tsc = securetsc_get_tsc_khz; early_memunmap(mem, PAGE_SIZE); -- 2.55.0.rc0.799.gd6f94ed593-goog