From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) (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 5BD8C489881 for ; Wed, 26 Aug 2026 21:33:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787780010; cv=none; b=esiyb4Pag0mXGQ08IAFM/jVMBi6Vxh/BnvcUQ22TDtSsGihmTtLnhCN7us/AHjYso63L26SBsUuCupUhybCo1KocvbHEJi+MAfuwnbUNr3kxCZVVxtJpae3j9sHe7cHerb1h3jxZKrJBEKz4our3b26eaSBGy7M2iAHRyrE8KnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787780010; c=relaxed/simple; bh=J7awBibVXHg+ZynoE1GTv8WNYcoD5LqJUOY9xR1n0xE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=nMOu0KW/8/wdCCD5SB2AJhdjIAebrog5gPnCnw9ioEIeKYUgrBeKMgtYCCCs/PCJ8nkIQt9EMsh8mLpi0lFU/z9dEO8mRlfg91RuAlZETQcn2pWfegwpMBegSwoAK+XYLGCMtX0jbYvy3Fqqpo8sYwgI9JC0dbb5FrdwkRiOHVk= 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=aVKQepFr; arc=none smtp.client-ip=209.85.215.200 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="aVKQepFr" Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-cbb467e56aaso27881a12.1 for ; Wed, 26 Aug 2026 14:33:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1787780008; x=1788384808; 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=Cl9yrkZ+dGZ9BiHgGOnk9QZOqiTp6OUnu1pYLMOniSs=; b=aVKQepFrPva+opNOkPQuvPBDbvjbdJLW6eh2rcI4ut4ImP31ggpHnIwoh2KHO+l52W ZlFhaOubrS0BgjylYaU54ARLgppnxb8XFujnMp1+esngwj+EG2JaGt8lg0c4MbwJSrRs eHumljUyvCELUlrU3LCyAkWxqF4hEY8xC3skAuveS+U7U6qSPSAlborBsPGIMNXsKiXT JLxEePsZ9pCzEj+n/gC2nnwxLRC8MTDA1xhY86CmVzNIvKez/IDbifcjx24EbtlfqTaA iqj9qGafluVb9tVUk02jByb+OA2iQI2hzXyxlXpUMNbko46X/XlvzNKnpeCcy2lRf60k Vmbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787780008; x=1788384808; 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=Cl9yrkZ+dGZ9BiHgGOnk9QZOqiTp6OUnu1pYLMOniSs=; b=bus/4Jos6HRBC5RzPZQ6htRfBVYqbeoh3oCRoewOJWG2RyPwB9Z46CcyakgfnINViZ cdwkpPIr+NKuzpS+NXazBPeEe5nnYcwSkyHlQis8xxyPm/FufnJ48Q6zKqNjdmkDR74W iGGIk94biOFzSl9UUcH3rveRUE3MSYk8tI/AqFDiO3ftIGyEjaf2v+rUe3aBGz92+QD6 IgX2Tvr3C0SJ7KTKNh61kNT/K6Pa6SKMEEuGEF6qrzAhBVl9qduoIAiu8aj6QHtNr0/w LC32RznC3vSWcBpGwqON7UDBOJB95b1woZdiouc+44gblxyJ3YYyEdCDKsj1Xqe1dNP6 c2Cg== X-Gm-Message-State: AFuF++lH4Hb9maB2WMO5T9iZCMI0G1Wo5Dh+B0dbpGryzxDLxf1u2IP6 d8f0viLqCz+4gIZz7gOHK65GmPKmEoKwdPjlCXTIYeRBBceFNtomyr642QFyj92XVQ4glz6UAuB PkasTXg== X-Received: from pgal6.prod.google.com ([2002:a63:3e06:0:b0:c9a:d174:5315]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:a03:b0:3c3:9c4e:de3a with SMTP id adf61e73a8af0-3cf82a348a3mr22345482637.6.1787780007516; Wed, 26 Aug 2026 14:33:27 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 26 Aug 2026 14:33:00 -0700 In-Reply-To: <20260826213303.914988-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260826213303.914988-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.887.g758fc8c411-goog Message-ID: <20260826213303.914988-21-seanjc@google.com> Subject: [PATCH v10 20/21] KVM: x86: Use kernel timekeeping snapshot for monotonic clock 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" Replace the KVM-private vgettsc()+/do_monotonic() timekeeping reimplementation with calls to the recently crafted, generic ktime_get_snapshot_id() interface. As noted previously, the snapshot provides both the system time and the raw_cycles (TSC), atomically paired using a sequence counter. Signed-off-by: David Woodhouse [sean: separate from other conversions] Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 33 ++++++--------------------------- 1 file changed, 6 insertions(+), 27 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 32390b20a2b4..0352bd147c40 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1438,29 +1438,6 @@ static inline u64 vgettsc(struct pvclock_clock *clock, u64 *tsc_timestamp, return v * clock->mult; } -/* - * This calculates CLOCK_MONOTONIC at the time of the TSC snapshot, with - * no boot time offset. - */ -static int do_monotonic(s64 *t, u64 *tsc_timestamp) -{ - struct pvclock_gtod_data *gtod = &pvclock_gtod_data; - unsigned long seq; - int mode; - u64 ns; - - do { - seq = read_seqcount_begin(>od->seq); - ns = gtod->clock.base_cycles; - ns += vgettsc(>od->clock, tsc_timestamp, &mode); - ns >>= gtod->clock.shift; - ns += ktime_to_ns(gtod->clock.offset); - } while (unlikely(read_seqcount_retry(>od->seq, seq))); - *t = ns; - - return mode; -} - static int do_realtime(struct timespec64 *ts, u64 *tsc_timestamp) { struct pvclock_gtod_data *gtod = &pvclock_gtod_data; @@ -1528,12 +1505,14 @@ static bool kvm_get_time_and_clockread(s64 *kernel_ns, u64 *tsc_timestamp) */ bool kvm_get_monotonic_and_clockread(s64 *kernel_ns, u64 *tsc_timestamp) { - /* checked again under seqlock below */ - if (!gtod_is_based_on_tsc(pvclock_gtod_data.clock.vclock_mode)) + struct system_time_snapshot snap = {}; + + ktime_get_snapshot_id(CLOCK_MONOTONIC, &snap); + if (!kvm_snapshot_has_tsc(&snap, tsc_timestamp)) return false; - return gtod_is_based_on_tsc(do_monotonic(kernel_ns, - tsc_timestamp)); + *kernel_ns = ktime_to_ns(snap.systime); + return true; } /* -- 2.55.0.887.g758fc8c411-goog