linux-kernel - [PATCH v4 06/38] x86/irq: Factor out common code for installing kvm irq handler

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Message-ID: <20250324173121.1275209-7-mizhang@google.com>
Date: Mon, 24 Mar 2025 17:30:46 +0000
From: Mingwei Zhang <mizhang@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, Liang@...gle.com, 
	Kan <kan.liang@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kvm@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	Mingwei Zhang <mizhang@...gle.com>, Yongwei Ma <yongwei.ma@...el.com>, 
	Xiong Zhang <xiong.y.zhang@...ux.intel.com>, Dapeng Mi <dapeng1.mi@...ux.intel.com>, 
	Jim Mattson <jmattson@...gle.com>, Sandipan Das <sandipan.das@....com>, 
	Zide Chen <zide.chen@...el.com>, Eranian Stephane <eranian@...gle.com>, 
	Das Sandipan <Sandipan.Das@....com>, Shukla Manali <Manali.Shukla@....com>, 
	Nikunj Dadhania <nikunj.dadhania@....com>
Subject: [PATCH v4 06/38] x86/irq: Factor out common code for installing kvm
 irq handler

From: Xiong Zhang <xiong.y.zhang@...ux.intel.com>

KVM will register irq handler for POSTED_INTR_WAKEUP_VECTOR and
KVM_GUEST_PMI_VECTOR, the existing kvm_set_posted_intr_wakeup_handler() is
renamed to x86_set_kvm_irq_handler(), and vector input parameter is used
to distinguish POSTED_INTR_WARKUP_VECTOR and KVM_GUEST_PMI_VECTOR.

Caller should call x86_set_kvm_irq_handler() once to register
a non-dummy handler for each vector. If caller register one
handler for a vector, later the caller register the same or different
non-dummy handler again, the second call will output warn message.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Xiong Zhang <xiong.y.zhang@...ux.intel.com>
Tested-by: Yongwei Ma <yongwei.ma@...el.com>
Signed-off-by: Mingwei Zhang <mizhang@...gle.com>
---
 arch/x86/include/asm/irq.h |  2 +-
 arch/x86/kernel/irq.c      | 18 ++++++++++++------
 arch/x86/kvm/vmx/vmx.c     |  4 ++--
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
index 194dfff84cb1..050a247b69b4 100644
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -30,7 +30,7 @@ struct irq_desc;
 extern void fixup_irqs(void);
 
 #if IS_ENABLED(CONFIG_KVM)
-extern void kvm_set_posted_intr_wakeup_handler(void (*handler)(void));
+void x86_set_kvm_irq_handler(u8 vector, void (*handler)(void));
 #endif
 
 extern void (*x86_platform_ipi_callback)(void);
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 385e3a5fc304..18cd418fe106 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -312,16 +312,22 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_x86_platform_ipi)
 static void dummy_handler(void) {}
 static void (*kvm_posted_intr_wakeup_handler)(void) = dummy_handler;
 
-void kvm_set_posted_intr_wakeup_handler(void (*handler)(void))
+void x86_set_kvm_irq_handler(u8 vector, void (*handler)(void))
 {
-	if (handler)
+	if (!handler)
+		handler = dummy_handler;
+
+	if (vector == POSTED_INTR_WAKEUP_VECTOR &&
+	    (handler == dummy_handler ||
+	     kvm_posted_intr_wakeup_handler == dummy_handler))
 		kvm_posted_intr_wakeup_handler = handler;
-	else {
-		kvm_posted_intr_wakeup_handler = dummy_handler;
+	else
+		WARN_ON_ONCE(1);
+
+	if (handler == dummy_handler)
 		synchronize_rcu();
-	}
 }
-EXPORT_SYMBOL_GPL(kvm_set_posted_intr_wakeup_handler);
+EXPORT_SYMBOL_GPL(x86_set_kvm_irq_handler);
 
 /*
  * Handler for POSTED_INTERRUPT_VECTOR.
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 6c56d5235f0f..00ac94535c21 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8279,7 +8279,7 @@ void vmx_migrate_timers(struct kvm_vcpu *vcpu)
 
 void vmx_hardware_unsetup(void)
 {
-	kvm_set_posted_intr_wakeup_handler(NULL);
+	x86_set_kvm_irq_handler(POSTED_INTR_WAKEUP_VECTOR, NULL);
 
 	if (nested)
 		nested_vmx_hardware_unsetup();
@@ -8583,7 +8583,7 @@ __init int vmx_hardware_setup(void)
 	if (r && nested)
 		nested_vmx_hardware_unsetup();
 
-	kvm_set_posted_intr_wakeup_handler(pi_wakeup_handler);
+	x86_set_kvm_irq_handler(POSTED_INTR_WAKEUP_VECTOR, pi_wakeup_handler);
 
 	return r;
 }
-- 
2.49.0.395.g12beb8f557-goog