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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 v8 08/17] KVM: x86: Wrap all of __get_kvmclock_master_clock() with CONFIG_X86_64=y
Date: Tue,  4 Aug 2026 16:39:12 -0700	[thread overview]
Message-ID: <20260804233923.3504629-9-seanjc@google.com> (raw)
In-Reply-To: <20260804233923.3504629-1-seanjc@google.com>

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

Wrap the entire use_master_clock block in #ifdef CONFIG_X86_64, since
use_master_clock is never true on 32-bit (host_tsc_clocksource is only
set under CONFIG_X86_64), and declare hv_clock inside the block so it is
not left as an unused variable on 32-bit.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
[sean: keep only the CONFIG_X86_64 ifdef, update changelog accordingly]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8666bd0337b8..cd2a140e8e63 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1654,8 +1654,10 @@ static unsigned long get_cpu_tsc_khz(void)
 static bool __get_kvmclock_master_clock(struct kvm *kvm,
 					struct kvm_clock_data *data)
 {
+#ifdef CONFIG_X86_64
 	struct kvm_arch *ka = &kvm->arch;
 	struct pvclock_vcpu_time_info hv_clock;
+	struct timespec64 ts;
 	u64 tsc_hz;
 
 	if (!ka->use_master_clock)
@@ -1672,25 +1674,24 @@ static bool __get_kvmclock_master_clock(struct kvm *kvm,
 	if (!tsc_hz)
 		return false;
 
-	{
-#ifdef CONFIG_X86_64
-		struct timespec64 ts;
-
-		if (kvm_get_walltime_and_clockread(&ts, &data->host_tsc)) {
-			data->realtime = ts.tv_nsec + NSEC_PER_SEC * ts.tv_sec;
-			data->flags |= KVM_CLOCK_REALTIME | KVM_CLOCK_HOST_TSC;
-		} else
-#endif
+	if (kvm_get_walltime_and_clockread(&ts, &data->host_tsc)) {
+		data->realtime = ts.tv_nsec + NSEC_PER_SEC * ts.tv_sec;
+		data->flags |= KVM_CLOCK_REALTIME | KVM_CLOCK_HOST_TSC;
+	} else {
 		data->host_tsc = rdtsc();
-
-		data->flags |= KVM_CLOCK_TSC_STABLE;
-		hv_clock.tsc_timestamp = ka->master_cycle_now;
-		hv_clock.system_time = ka->master_kernel_ns + ka->kvmclock_offset;
-		kvm_get_time_scale(NSEC_PER_SEC,  tsc_hz,
-				   &hv_clock.tsc_shift,
-				   &hv_clock.tsc_to_system_mul);
-		data->clock = __pvclock_read_cycles(&hv_clock, data->host_tsc);
 	}
+
+	data->flags |= KVM_CLOCK_TSC_STABLE;
+	hv_clock.tsc_timestamp = ka->master_cycle_now;
+	hv_clock.system_time = ka->master_kernel_ns + ka->kvmclock_offset;
+	kvm_get_time_scale(NSEC_PER_SEC,  tsc_hz,
+				&hv_clock.tsc_shift,
+				&hv_clock.tsc_to_system_mul);
+	data->clock = __pvclock_read_cycles(&hv_clock, data->host_tsc);
+	return true;
+#else
+	return false;
+#endif
 }
 
 static void get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data)
-- 
2.55.0.571.g244d577d93-goog


  parent reply	other threads:[~2026-08-04 23:39 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-04 23:39 [PATCH v8 00/17] KVM: x86: Cleaning up the KVM clock mess, part 1 Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 01/17] KVM: x86: Update "last guest TSC" snapshot prior to enabling IRQs/preemption Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 02/17] KVM: x86: Improve accuracy of KVM clock when TSC scaling is in force Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 03/17] KVM: x86: Explicitly disable TSC scaling without CONSTANT_TSC Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 04/17] KVM: x86: Activate master clock immediately on vCPU creation Sean Christopherson
2026-08-05  0:06   ` sashiko-bot
2026-08-05  9:11     ` David Woodhouse
2026-08-05 15:02       ` Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 05/17] KVM: x86: Avoid NTP frequency skew for KVM clock on 32-bit host Sean Christopherson
2026-08-05  0:02   ` sashiko-bot
2026-08-05 18:21     ` Sean Christopherson
2026-08-07  0:27       ` Sean Christopherson
2026-08-07 16:01         ` Sean Christopherson
2026-08-07 17:26           ` David Woodhouse
2026-08-08 15:08             ` David Woodhouse
2026-08-04 23:39 ` [PATCH v8 06/17] KVM: x86: Drop unnecessary CPU pinning when computing/getting kvmclock Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 07/17] KVM: x86: Move "no master clock" fallback from __get_kvmclock() to get_kvmclock() Sean Christopherson
2026-08-04 23:52   ` sashiko-bot
2026-08-05 15:17     ` Sean Christopherson
2026-08-04 23:39 ` Sean Christopherson [this message]
2026-08-04 23:39 ` [PATCH v8 09/17] KVM: x86: Fall back to non-master-clock if clockread fails in get_kvmclock() Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 10/17] KVM: x86: Fix KVM clock precision in get_kvmclock() with TSC scaling Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 11/17] KVM: x86: Use get_kvmclock() in kvm_get_wall_clock_epoch() Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 12/17] KVM: x86: Fix compute_guest_tsc() to handle negative time deltas Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 13/17] KVM: x86: Disable preemption, not IRQs, when getting TSC+freq pair Sean Christopherson
2026-08-04 23:56   ` sashiko-bot
2026-08-05 15:16     ` Sean Christopherson
2026-08-05 15:55       ` David Woodhouse
2026-08-05 16:22         ` Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 14/17] KVM: x86: Make master clock logic in guest PV clock updates 64-bit only Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 15/17] KVM: x86: Upscale TSC to "now", not master clock when updating PV clocks Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 16/17] KVM: x86: Simplify and comment kvm_get_time_scale() Sean Christopherson
2026-08-04 23:39 ` [PATCH v8 17/17] KVM: x86: Remove implicit rdtsc() from kvm_compute_l1_tsc_offset() Sean Christopherson

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