From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (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 4921542E8E1 for ; Wed, 1 Jul 2026 19:33:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934412; cv=none; b=mzu02csp1MJBkZUxHMf2kJvYZroolaA5YFdDsQvyI8P89kPtlUAhbDx/u4KcBUwHtIsRqMXi+pUm2pF+uCCr0kUuPzKp356oa0qjsrwjngV0qd806NGB0M5wOQTtpL/SkHoH8zy8Nof/K8tCBBOko6gHZmBc4qR7Xg1yC4hbkUo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934412; c=relaxed/simple; bh=t2gV+eBO9o787fvbLEefqahl8FVWKIIpfUP+z3tzyok=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=SsKa+A1ZHJWdQ6LvviY9Ck7l6P5pJORB79lddYP+pgz2zMa4FwuyiqyFFXQEtXJv5UeaC08jr0E7XriCiPM9beZhw3OaSx5Nab0j78B6+xu/3YqKi9GMWGtrLp9QDPA3yBkRenRaOfPQsq5w4Yo3UEZezY9/dRY3sXUudNLKNXc= 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=CpGN1P1H; arc=none smtp.client-ip=209.85.215.201 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="CpGN1P1H" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-c894c1c4aa9so929052a12.0 for ; Wed, 01 Jul 2026 12:33:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1782934408; x=1783539208; darn=vger.kernel.org; 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=ukYnz5D3jEol4z1WUeRHDVtFiLPopAappLYurzMw/rI=; b=CpGN1P1H52ALfmV+alPEufAf7OZvon8wnQ8RSUhwdN+rh0MsVG22DNGYwW1G3Sklve tgpt1TlLtiRwjPGPwvHyHTE2rIINLSOL6kEpl0umVw7vVlCFFJmnawfjTtANyEacNiFC QEaaSL49+7cbPBf5MI5EQrhzVS5pvCOwC8yvzAsqiIGu0G0KtuOliTEyZfpbu8KY02Ly B7IBv1vk/+FcKRViRdCS2Tt/v0m+coR1rSyNmfMdlw8wN0cGTFKMaGC0XUlGnTyfCWak 1OkT0CyamIAagzIgBkLYnxEUb70jLJBVnkSHpckGOgj7tytUB9DEEYkZ2cbQ6NZq6kOV /06Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782934408; x=1783539208; 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=ukYnz5D3jEol4z1WUeRHDVtFiLPopAappLYurzMw/rI=; b=gW3MyDGlLrakOELxDD74QqgZlzd7TkcW5LzNPlHTpy1Pf/9i5D17Ypws0HTz7SMhWA cH2T9pG8TWhrqlpeFFwzyycvZUskuskbjKyx+lDDBqcj6/+mUxjGn8cfYzmpN/z9sq/1 +6SlS7kHtD1LJD5J7s+qJ1r4VaIVpRF+BFDpQe0VLl/t/XVmp12Jh5S3QX4P7pHFihX7 mgY6Zns27p5ea/tB8sRZk+AHun4/9vtOQY9UUPA6HamG5Kxj/CJO6p7X1Xpt968uW342 ayjGomlxV8wd7uc9WoiIYOjmLmRfOB2ZEJn1D4ZfcOtN6AkfVfHXBa+fhSWnk0NAQhl4 QBRw== X-Forwarded-Encrypted: i=1; AFNElJ+18FDtkYX8pOPCfBmqjY37B3WbdS03gCddd2apeE9IXHhb5915UVjqYtc/8B+B7OLTGZ02gYI6mNJMOAA=@vger.kernel.org X-Gm-Message-State: AOJu0YwazEOzGEXE94Bd+UfKO92APRNTfoWsbVPzj8xBjAlOWRYcoPCo CmG3mRllhnuBqVg3oYH/g/HvYF8S51BfWB0TuAmVxwyFbH51t51spMiyreTxfWEja+oCg52kURy sM/cYJQ== X-Received: from pgad26.prod.google.com ([2002:a05:6a02:4f5a:b0:c99:d21a:f6b7]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:748b:b0:3bf:d1f9:b1db with SMTP id adf61e73a8af0-3bfed5e1001mr3530009637.52.1782934408107; Wed, 01 Jul 2026 12:33:28 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 1 Jul 2026 12:32:12 -0700 In-Reply-To: <20260701193212.749551-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org 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: <20260701193212.749551-52-seanjc@google.com> Subject: [PATCH v5 51/51] x86/kvm: Get local APIC bus frequency from PV CPUID Timing Info 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" 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. See Documentation/virt/kvm/x86/cpuid.rst for details. Reviewed-by: David Woodhouse Signed-off-by: Sean Christopherson --- arch/x86/kernel/kvm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index f9a6346077b0..beea0b6aa78e 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -990,7 +990,7 @@ 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 timing_info_leaf; + u32 timing_info_leaf, apic_khz; bool tsc_is_reliable; if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && @@ -1052,6 +1052,11 @@ 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; } + + /* The leaf also includes the local APIC bus/timer frequency.*/ + apic_khz = cpuid_ebx(timing_info_leaf); + if (apic_khz) + apic_set_timer_period_khz(apic_khz, "KVM hypervisor"); } /* -- 2.55.0.rc0.799.gd6f94ed593-goog