From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) (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 B5FD23F926D for ; Mon, 10 Aug 2026 22:55:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786402511; cv=none; b=R9J4M9Tg8juo1HwlSS6+tsI+nPSw1j6Grr8rUoGe7zNsDi1ONG/DXLpzRYhrswlb2V41LIZW6Jf3EuH1kP9JxYNwAoldehTO+M7GlecdLYFsxS5K0B2cedAU3vJFyjl6rzHguovCPhjF+Vs2ZpeUj5M7FM5ADUGurYwCtEmSPHo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786402511; c=relaxed/simple; bh=Enz6UW5jzOGeDIUWfw2NOrqdPdPLO7aFr63mUWyvVPU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=t96wtYxFgsNnNfiT/YcVddpEXmxsjGo0ifX0yrdNOwAPakSkF/iSIs/GIjSa7pMs/qHTIbXMwrfEhFicVX4OuT4ZlnULw2NwXUI/ZxyH7eAUojX9LWnz7wm6YrUptjkykF0wDPSgBQBf+6grNKizkyvxK5Fu0pGLdeaJgujwbV4= 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=m1lUxP8T; arc=none smtp.client-ip=209.85.210.199 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="m1lUxP8T" Received: by mail-pf1-f199.google.com with SMTP id d2e1a72fcca58-8488ac68185so6524670b3a.2 for ; Mon, 10 Aug 2026 15:55:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1786402508; x=1787007308; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:from:to:cc:subject:date:message-id :reply-to:content-type; bh=XHzSwUqdKhsWaqPZjcPYfGCwbZbHLD3pwjjXIIUeXRs=; b=m1lUxP8T4ZJmp5xD9IVYcfnx/+Bdp5OyuYe7HT6d6sHS8YlfBOAJbiLIvONkiGTxef 71+TXixa8wkAM2M7u3LeBuR+ASfVsrFz7npgb63MYaZ0olYDDXmPMnm9fleBUSNZdnet QM1l3gYU31xfGM++UUR8pD4wLTLzLR7nqg0coZqAR/22VW69BPYfgpGVC0OoMRSnmTh5 l09eAuA1AXsw5aiwgscEWIQpelvkfw/dCYtwzL4Nvsr7Pc/wCjoGe2iCG+9+qLjOQDGR SdmzjNwmhAvROy571j5okcjWdLSEH4mp/VldaZ4wB7JWJZAjz20IlV2EGl7Lq4roPjs9 u0iw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786402508; x=1787007308; h=content-type: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:content-type; bh=XHzSwUqdKhsWaqPZjcPYfGCwbZbHLD3pwjjXIIUeXRs=; b=TGbAoCQ76+WFffZrQZxdttzrufJlL32LFO8KzU2KifVUsVZyzjzr4ScVajlwAgGPnY a+dUaa8vPildHNQKf0l0liJyGf59KzqxG/Y1Q0iA0Ed+Kx2MO5tsX17rNMiSD3sh01gM ITSR6nvnbA/kLkgTIn2DZkyuoO/CQGMzvlq1/Wr69b1kzpNOYUysDSKd7I93FIbrJSF2 39Vp+3RQ5dT8BsfOn11gXZO2pJiZlmvak/5TKBWQNR/WHpcmNAOAOHyRf5vsD04i+31r Br1stvYXeC2FD0RbEVEWx81p71zcmGKlRcHvsFZj51T/BddLN+ANfe1UzNjof3sWal9s D+0A== X-Forwarded-Encrypted: i=1; AHgh+Rrd1XCQa4qhVndKJH06k8rSjWIT8xdHMrhYQOylQXOYaQPqKLP1MSdyVMjqIGDmpyH8YwyE1Uk9w1enxJM=@vger.kernel.org X-Gm-Message-State: AOJu0YxiBpU/uzcatfoZd7Brec1Q5a0UFlO1/jo6osPnBZWvjPJgfgkP RCr2p61JA8yDcmYdKZyWr3kROWlqB3GbrRXpM3E9oPiFrFknUfjovYXVC2PApDQrrWVkVpVfGaz U5xcN0A== X-Received: from pggq19.prod.google.com ([2002:a63:d613:0:b0:c9a:2926:8ac3]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:92a6:b0:848:2a55:7110 with SMTP id d2e1a72fcca58-84f6976eda2mr25023581b3a.36.1786402507740; Mon, 10 Aug 2026 15:55:07 -0700 (PDT) Reply-To: Sean Christopherson Date: Mon, 10 Aug 2026 15:54:42 -0700 In-Reply-To: <20260810225500.869288-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260810225500.869288-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.679.g6767b8d81c-goog Message-ID: <20260810225500.869288-5-seanjc@google.com> Subject: [PATCH v9 04/21] KVM: x86: Activate master clock immediately on vCPU creation From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Durrant , David Woodhouse , Dongli Zhang Content-Type: text/plain; charset="UTF-8" From: David Woodhouse Previously, the master clock was only activated when the first vCPU processed KVM_REQ_MASTERCLOCK_UPDATE during KVM_RUN. This meant that KVM_GET_CLOCK could not return the host_tsc field until after the first KVM_RUN, making it impossible for userspace to follow the documented TSC migration procedure without a dummy vCPU run. Fix this by calling kvm_update_masterclock() directly from kvm_arch_vcpu_postcreate(), after kvm_synchronize_tsc() has already set all_vcpus_matched_freq. This ensures the master clock is active immediately, and KVM_GET_CLOCK returns a valid {host_tsc, realtime} pair as soon as a vCPU exists. Signed-off-by: David Woodhouse Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ce6d155b2ee6..137a1dd2b85a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9447,6 +9447,8 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) return; vcpu_load(vcpu); kvm_synchronize_tsc(vcpu, NULL); + if (kvm_check_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu)) + kvm_update_masterclock(vcpu->kvm); vcpu_put(vcpu); /* poll control enabled by default */ -- 2.55.0.679.g6767b8d81c-goog