linux-kernel - [PATCH v6 14/44] KVM: Add a simplified wrapper for registering perf callbacks

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Message-ID: <20251206001720.468579-15-seanjc@google.com>
Date: Fri,  5 Dec 2025 16:16:50 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oupton@...nel.org>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Xin Li <xin@...or.com>, "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, 
	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: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, loongarch@...ts.linux.dev, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, Mingwei Zhang <mizhang@...gle.com>, 
	Xudong Hao <xudong.hao@...el.com>, Sandipan Das <sandipan.das@....com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>, Xiong Zhang <xiong.y.zhang@...ux.intel.com>, 
	Manali Shukla <manali.shukla@....com>, Jim Mattson <jmattson@...gle.com>
Subject: [PATCH v6 14/44] KVM: Add a simplified wrapper for registering perf callbacks

Add a parameter-less API for registering perf callbacks in anticipation of
introducing another x86-only parameter for handling mediated PMU PMIs.

No functional change intended.

Acked-by: Anup Patel <anup@...infault.org>
Tested-by: Xudong Hao <xudong.hao@...el.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/arm64/kvm/arm.c      |  2 +-
 arch/loongarch/kvm/main.c |  2 +-
 arch/riscv/kvm/main.c     |  2 +-
 arch/x86/kvm/x86.c        |  2 +-
 include/linux/kvm_host.h  | 11 +++++++++--
 virt/kvm/kvm_main.c       |  5 +++--
 6 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 97627638e802..153166ca626a 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2357,7 +2357,7 @@ static int __init init_subsystems(void)
 	if (err)
 		goto out;
 
-	kvm_register_perf_callbacks(NULL);
+	kvm_register_perf_callbacks();
 
 out:
 	if (err)
diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
index 80ea63d465b8..f62326fe29fa 100644
--- a/arch/loongarch/kvm/main.c
+++ b/arch/loongarch/kvm/main.c
@@ -394,7 +394,7 @@ static int kvm_loongarch_env_init(void)
 	}
 
 	kvm_init_gcsr_flag();
-	kvm_register_perf_callbacks(NULL);
+	kvm_register_perf_callbacks();
 
 	/* Register LoongArch IPI interrupt controller interface. */
 	ret = kvm_loongarch_register_ipi_device();
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 45536af521f0..0f3fe3986fc0 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -174,7 +174,7 @@ static int __init riscv_kvm_init(void)
 
 	kvm_riscv_setup_vendor_features();
 
-	kvm_register_perf_callbacks(NULL);
+	kvm_register_perf_callbacks();
 
 	rc = kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
 	if (rc) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0c6d899d53dd..1b2827cecf38 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10107,7 +10107,7 @@ int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
 		set_hv_tscchange_cb(kvm_hyperv_tsc_notifier);
 #endif
 
-	kvm_register_perf_callbacks(ops->handle_intel_pt_intr);
+	__kvm_register_perf_callbacks(ops->handle_intel_pt_intr, NULL);
 
 	if (IS_ENABLED(CONFIG_KVM_SW_PROTECTED_VM) && tdp_mmu_enabled)
 		kvm_caps.supported_vm_types |= BIT(KVM_X86_SW_PROTECTED_VM);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d93f75b05ae2..8e410d1a63df 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1749,10 +1749,17 @@ static inline bool kvm_arch_intc_initialized(struct kvm *kvm)
 #ifdef CONFIG_GUEST_PERF_EVENTS
 unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu);
 
-void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void));
+void __kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void),
+				   void (*mediated_pmi_handler)(void));
+
+static inline void kvm_register_perf_callbacks(void)
+{
+	__kvm_register_perf_callbacks(NULL, NULL);
+}
+
 void kvm_unregister_perf_callbacks(void);
 #else
-static inline void kvm_register_perf_callbacks(void *ign) {}
+static inline void kvm_register_perf_callbacks(void) {}
 static inline void kvm_unregister_perf_callbacks(void) {}
 #endif /* CONFIG_GUEST_PERF_EVENTS */
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4954cbbb05e8..16b24da9cda5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -6474,10 +6474,11 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
 	.handle_mediated_pmi	= NULL,
 };
 
-void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
+void __kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void),
+				   void (*mediated_pmi_handler)(void))
 {
 	kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
-	kvm_guest_cbs.handle_mediated_pmi = NULL;
+	kvm_guest_cbs.handle_mediated_pmi = mediated_pmi_handler;
 
 	perf_register_guest_info_callbacks(&kvm_guest_cbs);
 }
-- 
2.52.0.223.gf5cc29aaa4-goog