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From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 Paul Durrant <paul@xen.org>, David Woodhouse <dwmw@amazon.co.uk>,
	Dongli Zhang <dongli.zhang@oracle.com>
Subject: [PATCH v9 05/21] KVM: x86: Compute kvmclock base without pvclock_gtod_data
Date: Mon, 10 Aug 2026 15:54:43 -0700	[thread overview]
Message-ID: <20260810225500.869288-6-seanjc@google.com> (raw)
In-Reply-To: <20260810225500.869288-1-seanjc@google.com>

From: David Woodhouse <dwmw@amazon.co.uk>

get_kvmclock_base_ns() needs CLOCK_MONOTONIC_RAW + offs_boot. Compute
this directly rather than reading offs_boot from the pvclock_gtod_data
private copy. offs_boot only changes at suspend/resume so does not
need to be atomically paired with the raw clock read.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Assisted-by: Kiro:claude-opus-4.6-1m
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 137a1dd2b85a..67c762b3bf28 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -930,7 +930,7 @@ static void update_pvclock_gtod(struct timekeeper *tk)
 static s64 get_kvmclock_base_ns(void)
 {
 	/* Count up from boot time, but with the frequency of the raw clock.  */
-	return ktime_to_ns(ktime_add(ktime_get_raw(), pvclock_gtod_data.offs_boot));
+	return ktime_to_ns(ktime_mono_to_any(ktime_get_raw(), TK_OFFS_BOOT));
 }
 #else
 static s64 get_kvmclock_base_ns(void)
-- 
2.55.0.679.g6767b8d81c-goog


  parent reply	other threads:[~2026-08-10 22:55 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-10 22:54 [PATCH v9 00/21] KVM: x86: Cleaning up the KVM clock mess, part 1 Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 01/21] KVM: x86: Update "last guest TSC" snapshot prior to enabling IRQs/preemption Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 02/21] KVM: x86: Improve accuracy of KVM clock when TSC scaling is in force Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 03/21] KVM: x86: Explicitly disable TSC scaling without CONSTANT_TSC Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 04/21] KVM: x86: Activate master clock immediately on vCPU creation Sean Christopherson
2026-08-10 22:54 ` Sean Christopherson [this message]
2026-08-10 22:54 ` [PATCH v9 06/21] KVM: x86: Avoid NTP frequency skew for KVM clock on 32-bit host Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 07/21] KVM: x86: Drop unnecessary CPU pinning when computing/getting kvmclock Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 08/21] KVM: x86: Move "no master clock" fallback from __get_kvmclock() to get_kvmclock() Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 09/21] KVM: x86: Wrap all of __get_kvmclock_master_clock() with CONFIG_X86_64=y Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 10/21] KVM: x86: Fall back to non-master-clock if clockread fails in get_kvmclock() Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 11/21] KVM: x86: Fix KVM clock precision in get_kvmclock() with TSC scaling Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 12/21] KVM: x86: Use get_kvmclock() in kvm_get_wall_clock_epoch() Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 13/21] KVM: x86: Fix compute_guest_tsc() to handle negative time deltas Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 14/21] KVM: x86: Disable preemption, not IRQs, when getting TSC+freq pair Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 15/21] KVM: x86: Make master clock logic in guest PV clock updates 64-bit only Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 16/21] KVM: x86: Upscale TSC to "now", not master clock when updating PV clocks Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 17/21] KVM: x86: Simplify and comment kvm_get_time_scale() Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 18/21] KVM: x86: Remove implicit rdtsc() from kvm_compute_l1_tsc_offset() Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 19/21] KVM: x86: Use kernel timekeeping snapshots for getting kvmclock time since boot Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 20/21] KVM: x86: Use kernel timekeeping snapshot for monotonic clock Sean Christopherson
2026-08-10 22:54 ` [PATCH v9 21/21] KVM: x86: Use kernel timekeeping snapshot to get walltime+TSC Sean Christopherson

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