Linux Documentation
 help / color / mirror / Atom feed
From: David Woodhouse <dwmw2@infradead.org>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Sean Christopherson <seanjc@google.com>,
	Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Paul Durrant <paul@xen.org>, Jonathan Cameron <jic23@kernel.org>,
	Sascha Bischoff <Sascha.Bischoff@arm.com>,
	Marc Zyngier <maz@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
	Jack Allister <jalliste@amazon.com>,
	Dongli Zhang <dongli.zhang@oracle.com>,
	joe.jin@oracle.com, kvm@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	xen-devel@lists.xenproject.org, linux-kselftest@vger.kernel.org
Subject: [PATCH v4 10/30] KVM: x86: Fold __get_kvmclock() into get_kvmclock()
Date: Sat,  9 May 2026 23:46:36 +0100	[thread overview]
Message-ID: <20260509224824.3264567-11-dwmw2@infradead.org> (raw)
In-Reply-To: <20260509224824.3264567-1-dwmw2@infradead.org>

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

There is no need for the separate __get_kvmclock() helper; just inline
its body into get_kvmclock() within the seqcount retry loop.

No functional change.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 arch/x86/kvm/x86.c | 63 +++++++++++++++++++++-------------------------
 1 file changed, 28 insertions(+), 35 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ccdfd3fa3402..6f660c3210ee 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3200,50 +3200,43 @@ static unsigned long get_cpu_tsc_khz(void)
 		return __this_cpu_read(cpu_tsc_khz);
 }
 
-/* Called within read_seqcount_begin/retry for kvm->pvclock_sc.  */
-static void __get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data)
+static void get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data)
 {
 	struct kvm_arch *ka = &kvm->arch;
 	struct pvclock_vcpu_time_info hv_clock;
+	unsigned int seq;
 
-	/* both __this_cpu_read() and rdtsc() should be on the same cpu */
-	get_cpu();
+	do {
+		seq = read_seqcount_begin(&ka->pvclock_sc);
 
-	data->flags = 0;
-	if (ka->use_master_clock &&
-	    (static_cpu_has(X86_FEATURE_CONSTANT_TSC) || __this_cpu_read(cpu_tsc_khz))) {
+		/* both __this_cpu_read() and rdtsc() should be on the same cpu */
+		get_cpu();
+
+		data->flags = 0;
+		if (ka->use_master_clock &&
+		    (static_cpu_has(X86_FEATURE_CONSTANT_TSC) || __this_cpu_read(cpu_tsc_khz))) {
 #ifdef CONFIG_X86_64
-		struct timespec64 ts;
+			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
+			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
-		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, get_cpu_tsc_khz() * 1000LL,
-				   &hv_clock.tsc_shift,
-				   &hv_clock.tsc_to_system_mul);
-		data->clock = __pvclock_read_cycles(&hv_clock, data->host_tsc);
-	} else {
-		data->clock = get_kvmclock_base_ns() + ka->kvmclock_offset;
-	}
-
-	put_cpu();
-}
-
-static void get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data)
-{
-	struct kvm_arch *ka = &kvm->arch;
-	unsigned seq;
+			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, get_cpu_tsc_khz() * 1000LL,
+					   &hv_clock.tsc_shift,
+					   &hv_clock.tsc_to_system_mul);
+			data->clock = __pvclock_read_cycles(&hv_clock, data->host_tsc);
+		} else {
+			data->clock = get_kvmclock_base_ns() + ka->kvmclock_offset;
+		}
 
-	do {
-		seq = read_seqcount_begin(&ka->pvclock_sc);
-		__get_kvmclock(kvm, data);
+		put_cpu();
 	} while (read_seqcount_retry(&ka->pvclock_sc, seq));
 }
 
-- 
2.51.0


  parent reply	other threads:[~2026-05-09 22:49 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-09 22:46 [PATCH v4] 00/30] Cleaning up the KVM clock mess David Woodhouse
2026-05-09 22:46 ` [PATCH v4 01/30] KVM: x86/xen: Do not corrupt KVM clock in kvm_xen_shared_info_init() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 02/30] KVM: x86: Improve accuracy of KVM clock when TSC scaling is in force David Woodhouse
2026-05-09 22:46 ` [PATCH v4 03/30] UAPI: x86: Move pvclock-abi to UAPI for x86 platforms David Woodhouse
2026-05-09 22:46 ` [PATCH v4 04/30] KVM: x86: Add KVM_[GS]ET_CLOCK_GUEST for accurate KVM clock migration David Woodhouse
2026-05-09 22:46 ` [PATCH v4 05/30] KVM: selftests: Add KVM/PV clock selftest to prove timer correction David Woodhouse
2026-05-09 22:46 ` [PATCH v4 06/30] KVM: x86: Explicitly disable TSC scaling without CONSTANT_TSC David Woodhouse
2026-05-09 22:46 ` [PATCH v4 07/30] KVM: x86: Add KVM_VCPU_TSC_SCALE and fix the documentation on TSC migration David Woodhouse
2026-05-09 22:46 ` [PATCH v4 08/30] KVM: x86: Avoid NTP frequency skew for KVM clock on 32-bit host David Woodhouse
2026-05-09 22:46 ` [PATCH v4 09/30] KVM: x86: WARN if kvm_get_walltime_and_clockread() fails unexpectedly David Woodhouse
2026-05-09 22:46 ` David Woodhouse [this message]
2026-05-09 22:46 ` [PATCH v4 11/30] KVM: x86: Add WARN and restructure get_kvmclock() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 12/30] KVM: x86: Use get_kvmclock_base_ns() as fallback in get_kvmclock() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 13/30] KVM: x86: Fix KVM clock precision in get_kvmclock() with TSC scaling David Woodhouse
2026-05-09 22:46 ` [PATCH v4 14/30] KVM: x86: Use get_kvmclock() in kvm_get_wall_clock_epoch() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 15/30] KVM: x86: Fix compute_guest_tsc() to handle negative time deltas David Woodhouse
2026-05-09 22:46 ` [PATCH v4 16/30] KVM: x86: Restructure kvm_guest_time_update() for TSC upscaling David Woodhouse
2026-05-09 22:46 ` [PATCH v4 17/30] KVM: x86: Simplify and comment kvm_get_time_scale() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 18/30] KVM: x86: Remove implicit rdtsc() from kvm_compute_l1_tsc_offset() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 19/30] KVM: x86: Improve synchronization in kvm_synchronize_tsc() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 20/30] KVM: x86: Kill last_tsc_{nsec,write,offset} fields David Woodhouse
2026-05-09 22:46 ` [PATCH v4 21/30] KVM: x86: Replace nr_vcpus_matched_tsc count with all_vcpus_matched_tsc bool David Woodhouse
2026-05-09 22:46 ` [PATCH v4 22/30] KVM: x86: Allow KVM master clock mode when TSCs are offset from each other David Woodhouse
2026-05-09 22:46 ` [PATCH v4 23/30] KVM: x86: Factor out kvm_use_master_clock() David Woodhouse
2026-05-09 22:46 ` [PATCH v4 24/30] KVM: x86: Avoid gratuitous global clock updates David Woodhouse
2026-05-09 22:46 ` [PATCH v4 25/30] KVM: x86/xen: Prevent runstate times from becoming negative David Woodhouse
2026-05-09 22:46 ` [PATCH v4 26/30] KVM: x86: Avoid redundant masterclock updates from multiple vCPUs David Woodhouse
2026-05-09 22:46 ` [PATCH v4 27/30] KVM: x86: Add KVM_VCPU_TSC_EFFECTIVE_FREQ attribute David Woodhouse
2026-05-09 22:46 ` [PATCH v4 28/30] KVM: x86: Remove runtime Xen TSC frequency CPUID update David Woodhouse
2026-05-09 22:46 ` [PATCH v4 29/30] x86/kvm: Obtain TSC frequency from CPUID if present David Woodhouse
2026-05-09 22:46 ` [PATCH v4 30/30] x86/xen: " David Woodhouse
2026-05-10 20:56 ` [PATCH v4 33/30] KVM: selftests: Add Xen runstate migration test David Woodhouse
2026-05-10 20:58 ` [PATCH v4 31/30] KVM: selftests: Add Xen/generic CPUID timing leaf test David Woodhouse
2026-05-10 21:05 ` [PATCH v4 32/30] KVM: x86: Re-synchronize TSC after KVM_SET_TSC_KHZ David Woodhouse

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20260509224824.3264567-11-dwmw2@infradead.org \
    --to=dwmw2@infradead.org \
    --cc=Sascha.Bischoff@arm.com \
    --cc=boris.ostrovsky@oracle.com \
    --cc=bp@alien8.de \
    --cc=corbet@lwn.net \
    --cc=dave.hansen@linux.intel.com \
    --cc=dongli.zhang@oracle.com \
    --cc=hpa@zytor.com \
    --cc=jalliste@amazon.com \
    --cc=jgross@suse.com \
    --cc=jic23@kernel.org \
    --cc=joe.jin@oracle.com \
    --cc=joey.gouly@arm.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=maz@kernel.org \
    --cc=mingo@redhat.com \
    --cc=paul@xen.org \
    --cc=pbonzini@redhat.com \
    --cc=seanjc@google.com \
    --cc=skhan@linuxfoundation.org \
    --cc=tglx@kernel.org \
    --cc=vkuznets@redhat.com \
    --cc=x86@kernel.org \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox