From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 5AA523FE37A for ; Fri, 29 May 2026 14:45:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780065916; cv=none; b=g7DN6eHNpaHIMg2hMqqdnN1YZ9NeCwkPOMjYszA8cGQgAR6zKNOkzLQs+ZFuyFvvNwnuK0b/AvKbPL+4JDamfzOG3K+r2PgnzmceIYVNqkxe6OUTh2+THp9CUt85lEhKxfr4DkoSY3CETrdgo5Y32nPqjaWyi3Xbu/meVV0PbDY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780065916; c=relaxed/simple; bh=UUytjfT9SVOtFZ9usAuTuI+mwQ/wQQjELPCBSRuUOk4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=GApwJLijxsBAw2xiOdiW0x25QqHp5lhw7Fb9KfH6CoWZAV+Yz+P7JeG32BehkD4OauVOHLRTzEmpaCpjzKnFRIVgbD4LVpmIqGgcXjPT855RL1LTKEUZmNczXHDK3zxVhB6ChTpsJSV2BJZidm/062M1tBKI3sKLTFF8sBIX/pU= 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=TwPFmzAj; arc=none smtp.client-ip=209.85.214.201 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="TwPFmzAj" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2bc763c7256so290876455ad.3 for ; Fri, 29 May 2026 07:45:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780065914; x=1780670714; 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=Xkng2ObvqyeOAHFFD1k5jEREhKyPX3M1bjFdIhQCaZo=; b=TwPFmzAjT1sqs+5Bqv4wHTT4aZdwms4ix1o+dfOTxqCDE9Ey8gWRDOdxPhSmz9Eikf b579Aut684RjUcIwS/jFt7JW+ciC7RIj4aCExzgQgBWth6Ln4MTgmp5ryMB9GkZbVFrD fuvM2CT93HRPElzwEiNfhBKjmPQVLPoSU2fw06NdSPpM88++37c4Lt0q8+JL3xj8hLUI ATa68eU+VwHi0IRh80nViRnpFOUa8ykcpH9W5U7rYjTpHgbTm5ZI52MscJY+lDmL37GD 2Wwz3j8rxO9tGIITMLb67NNuqyyXuEk3y5pOxxi7LRa8H0pTZPxSXGEeCA1VAcdofsxa 6j+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780065914; x=1780670714; 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=Xkng2ObvqyeOAHFFD1k5jEREhKyPX3M1bjFdIhQCaZo=; b=QdgK72ViEeAYUgutBCbUA2LEOoRx4tLc0JINkulnRPa481u7v7XZG7Vinz+LslDuQ8 ED+Kr9GPHdhtzvoCvSqr2G5YlFOnyVIYFw8marHPIVRoZxBTZ5GszewmDSjqSw9jhVqr rI4e/6XS3EJ8+bmoPL1IDa7yWvnFj81JLpIRYMXa1tCJXmINM7mWRUf56MfvwmKJYUa5 ZHnQaj1j5+H5F78k77We1syUklNaWvyX/vy2Jfwa+4GGBIohO2ermmFtVXfCT8QMzfLt xPMnCgqcJo4IBSRyLGXDrwBgsKTAx1rY5kWftzJbw5aEhnG5ZuxFevZOCYv9noGLND5I RVug== X-Forwarded-Encrypted: i=1; AFNElJ/YQK6K06A6Z25VANw71Um2CZJYFc8kTJL2JfZ3twnxNZMbgZkSVyjWQRYPHH1o2q/2YVWHXRmooBCi@lists.linux.dev X-Gm-Message-State: AOJu0Yz0npUMR5xSGKhhDRR6depYddR5RrhR0d8oROfqgQL08s5YdPAE ZrAbt3945sE2/r6PzCkYxtuFZQpuC70K1sNd7akhNwpH0eixmedvPmw+WoYVdvCWpbIl7ljZqL4 hN0wrXQ== X-Received: from plhl2.prod.google.com ([2002:a17:903:1202:b0:2b0:5b0d:f4db]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:1508:b0:2bc:b141:8551 with SMTP id d9443c01a7336-2bf36833ef4mr1185145ad.19.1780065913278; Fri, 29 May 2026 07:45:13 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 29 May 2026 07:44:05 -0700 In-Reply-To: <20260529144435.704127-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260529144435.704127-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529144435.704127-19-seanjc@google.com> Subject: [PATCH v4 18/47] x86/kvm: Get local APIC bus frequency from PV CPUID Timing Info From: Sean Christopherson To: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , 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: "H. Peter Anvin" , Rick Edgecombe , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , 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, David Woodhouse , Tom Lendacky , Nikunj A Dadhania , David Woodhouse , Michael Kelley , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" When running as a KVM guest with PV timing info provided by the host, stuff the APIC timer period/frequency with the local APIC bus frequency reported in CPUID.0x40000010.EBX instead of trying to calibrate/guess the frequency. Note, the unit of measurement for lapic_timer_period is "ticks per HZ", not Khz. See Documentation/virt/kvm/x86/cpuid.rst for details. Signed-off-by: Sean Christopherson --- arch/x86/kernel/kvm.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 4fe9c69bf40b..c1139182121d 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -977,6 +977,7 @@ static void __init kvm_init_platform(void) .mask_lo = (u32)(~(SZ_4G - tolud - 1)) | MTRR_PHYSMASK_V, .mask_hi = (BIT_ULL(boot_cpu_data.x86_phys_bits) - 1) >> 32, }; + u32 apic_khz __maybe_unused; u32 timing_info_leaf; bool tsc_is_reliable; @@ -1039,6 +1040,13 @@ static void __init kvm_init_platform(void) x86_init.hyper.get_tsc_khz = kvm_get_tsc_khz; x86_init.hyper.get_cpu_khz = kvm_get_tsc_khz; } + +#ifdef CONFIG_X86_LOCAL_APIC + /* The leaf also includes the local APIC bus/timer frequency.*/ + apic_khz = cpuid_ebx(timing_info_leaf); + if (apic_khz) + lapic_timer_period = apic_khz * 1000 / HZ; +#endif } /* -- 2.54.0.823.g6e5bcc1fc9-goog