linux-kernel - [PATCH v2 17/38] x86/tsc: WARN if TSC sched_clock save/restore used with PV sched

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Message-ID: <20250227021855.3257188-18-seanjc@google.com>
Date: Wed, 26 Feb 2025 18:18:33 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Sean Christopherson <seanjc@...gle.com>, Juergen Gross <jgross@...e.com>, 
	"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
	Dexuan Cui <decui@...rosoft.com>, Ajay Kaher <ajay.kaher@...adcom.com>, 
	Jan Kiszka <jan.kiszka@...mens.com>, Andy Lutomirski <luto@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	John Stultz <jstultz@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	kvm@...r.kernel.org, virtualization@...ts.linux.dev, 
	linux-hyperv@...r.kernel.org, xen-devel@...ts.xenproject.org, 
	Tom Lendacky <thomas.lendacky@....com>, Nikunj A Dadhania <nikunj@....com>
Subject: [PATCH v2 17/38] x86/tsc: WARN if TSC sched_clock save/restore used
 with PV sched_clock

Now that all PV clocksources override the sched_clock save/restore hooks
when overriding sched_clock, WARN if the "default" TSC hooks are invoked
when using a PV sched_clock, e.g. to guard against regressions.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kernel/tsc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 472d6c71d3a5..5501d76243c8 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -990,7 +990,7 @@ static unsigned long long cyc2ns_suspend;
 
 void tsc_save_sched_clock_state(void)
 {
-	if (!sched_clock_stable())
+	if (!sched_clock_stable() || WARN_ON_ONCE(!using_native_sched_clock()))
 		return;
 
 	cyc2ns_suspend = sched_clock();
@@ -1010,7 +1010,7 @@ void tsc_restore_sched_clock_state(void)
 	unsigned long flags;
 	int cpu;
 
-	if (!sched_clock_stable())
+	if (!sched_clock_stable() || WARN_ON_ONCE(!using_native_sched_clock()))
 		return;
 
 	local_irq_save(flags);
-- 
2.48.1.711.g2feabab25a-goog