Move x86's perf guest callbacks into common KVM, as they are semantically
identical to arm64's callbacks (the only other such KVM callbacks).
arm64 will convert to the common versions in a future patch.

Implement the necessary arm64 arch hooks now to avoid having to provide
stubs or a temporary #define (from x86) to avoid arm64 compilation errors
when CONFIG_GUEST_PERF_EVENTS=y.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/include/asm/kvm_host.h |  8 +++++
 arch/arm64/kvm/arm.c              |  5 +++
 arch/x86/include/asm/kvm_host.h   |  3 ++
 arch/x86/kvm/x86.c                | 53 +++++++------------------------
 include/linux/kvm_host.h          | 10 ++++++
 virt/kvm/kvm_main.c               | 44 +++++++++++++++++++++++++
 6 files changed, 81 insertions(+), 42 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index ed940aec89e0..828b6eaa2c56 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -673,6 +673,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
 void kvm_perf_init(void);
 void kvm_perf_teardown(void);
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
+static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
+{
+	/* Any callback while a vCPU is loaded is considered to be in guest. */
+	return !!vcpu;
+}
+#endif
+
 long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
 gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
 void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e9a2b8f27792..2b542fdc237e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -500,6 +500,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 	return vcpu_mode_priv(vcpu);
 }
 
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
+{
+	return *vcpu_pc(vcpu);
+}
+
 /* Just ensure a guest exit from a particular CPU */
 static void exit_vm_noop(void *info)
 {
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2d86a2dfc775..6efe4e03a6d2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1543,6 +1543,9 @@ static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
 		return -ENOTSUPP;
 }
 
+#define kvm_arch_pmi_in_guest(vcpu) \
+	((vcpu) && (vcpu)->arch.handling_intr_from_guest)
+
 int kvm_mmu_module_init(void);
 void kvm_mmu_module_exit(void);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 412646b973bb..1bea616402e6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8264,43 +8264,12 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-static inline bool kvm_pmi_in_guest(struct kvm_vcpu *vcpu)
-{
-	return vcpu && vcpu->arch.handling_intr_from_guest;
-}
-
-static unsigned int kvm_guest_state(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-	unsigned int state;
-
-	if (!kvm_pmi_in_guest(vcpu))
-		return 0;
-
-	state = PERF_GUEST_ACTIVE;
-	if (static_call(kvm_x86_get_cpl)(vcpu))
-		state |= PERF_GUEST_USER;
-
-	return state;
-}
-
-static unsigned long kvm_guest_get_ip(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-
-	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
-	if (WARN_ON_ONCE(!kvm_pmi_in_guest(vcpu)))
-		return 0;
-
-	return kvm_rip_read(vcpu);
-}
-
 static unsigned int kvm_handle_intel_pt_intr(void)
 {
 	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	/* '0' on failure so that the !PT case can use a RET0 static call. */
-	if (!kvm_pmi_in_guest(vcpu))
+	if (!kvm_arch_pmi_in_guest(vcpu))
 		return 0;
 
 	kvm_make_request(KVM_REQ_PMI, vcpu);
@@ -8309,12 +8278,6 @@ static unsigned int kvm_handle_intel_pt_intr(void)
 	return 1;
 }
 
-static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.state			= kvm_guest_state,
-	.get_ip			= kvm_guest_get_ip,
-	.handle_intel_pt_intr	= NULL,
-};
-
 #ifdef CONFIG_X86_64
 static void pvclock_gtod_update_fn(struct work_struct *work)
 {
@@ -11068,9 +11031,11 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	/* Temporary ugliness. */
 	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
-		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
-	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+		kvm_register_perf_callbacks(kvm_handle_intel_pt_intr);
+	else
+		kvm_register_perf_callbacks(NULL);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
 		supported_xss = 0;
@@ -11099,8 +11064,7 @@ int kvm_arch_hardware_setup(void *opaque)
 
 void kvm_arch_hardware_unsetup(void)
 {
-	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
-	kvm_guest_cbs.handle_intel_pt_intr = NULL;
+	kvm_unregister_perf_callbacks();
 
 	static_call(kvm_x86_hardware_unsetup)();
 }
@@ -11727,6 +11691,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 	return vcpu->arch.preempted_in_kernel;
 }
 
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
+{
+	return kvm_rip_read(vcpu);
+}
+
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e4d712e9f760..b9255a6439f2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1163,6 +1163,16 @@ static inline bool kvm_arch_intc_initialized(struct kvm *kvm)
 }
 #endif
 
+#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_unregister_perf_callbacks(void);
+#else
+static inline void kvm_register_perf_callbacks(void *ign) {}
+static inline void kvm_unregister_perf_callbacks(void) {}
+#endif /* CONFIG_GUEST_PERF_EVENTS */
+
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type);
 void kvm_arch_destroy_vm(struct kvm *kvm);
 void kvm_arch_sync_events(struct kvm *kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3e67c93ca403..179fb110a00f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5460,6 +5460,50 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
         return &kvm_running_vcpu;
 }
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
+static unsigned int kvm_guest_state(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+	unsigned int state;
+
+	if (!kvm_arch_pmi_in_guest(vcpu))
+		return 0;
+
+	state = PERF_GUEST_ACTIVE;
+	if (!kvm_arch_vcpu_in_kernel(vcpu))
+		state |= PERF_GUEST_USER;
+
+	return state;
+}
+
+static unsigned long kvm_guest_get_ip(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+
+	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
+	if (WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)))
+		return 0;
+
+	return kvm_arch_vcpu_get_ip(vcpu);
+}
+
+static struct perf_guest_info_callbacks kvm_guest_cbs = {
+	.state			= kvm_guest_state,
+	.get_ip			= kvm_guest_get_ip,
+	.handle_intel_pt_intr	= NULL,
+};
+
+void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
+{
+	kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+}
+void kvm_unregister_perf_callbacks(void)
+{
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+}
+#endif
+
 struct kvm_cpu_compat_check {
 	void *opaque;
 	int *ret;
-- 
2.33.0.464.g1972c5931b-goog

On 22/09/21 02:05, Sean Christopherson wrote:
> Move x86's perf guest callbacks into common KVM, as they are semantically
> identical to arm64's callbacks (the only other such KVM callbacks).
> arm64 will convert to the common versions in a future patch.
> 
> Implement the necessary arm64 arch hooks now to avoid having to provide
> stubs or a temporary #define (from x86) to avoid arm64 compilation errors
> when CONFIG_GUEST_PERF_EVENTS=y.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>   arch/arm64/include/asm/kvm_host.h |  8 +++++
>   arch/arm64/kvm/arm.c              |  5 +++
>   arch/x86/include/asm/kvm_host.h   |  3 ++
>   arch/x86/kvm/x86.c                | 53 +++++++------------------------
>   include/linux/kvm_host.h          | 10 ++++++
>   virt/kvm/kvm_main.c               | 44 +++++++++++++++++++++++++
>   6 files changed, 81 insertions(+), 42 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index ed940aec89e0..828b6eaa2c56 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -673,6 +673,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
>   void kvm_perf_init(void);
>   void kvm_perf_teardown(void);
>   
> +#ifdef CONFIG_GUEST_PERF_EVENTS
> +static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
> +{
> +	/* Any callback while a vCPU is loaded is considered to be in guest. */
> +	return !!vcpu;
> +}
> +#endif
> +
>   long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
>   gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
>   void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index e9a2b8f27792..2b542fdc237e 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -500,6 +500,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
>   	return vcpu_mode_priv(vcpu);
>   }
>   
> +unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
> +{
> +	return *vcpu_pc(vcpu);
> +}
> +
>   /* Just ensure a guest exit from a particular CPU */
>   static void exit_vm_noop(void *info)
>   {
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 2d86a2dfc775..6efe4e03a6d2 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1543,6 +1543,9 @@ static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
>   		return -ENOTSUPP;
>   }
>   
> +#define kvm_arch_pmi_in_guest(vcpu) \
> +	((vcpu) && (vcpu)->arch.handling_intr_from_guest)
> +
>   int kvm_mmu_module_init(void);
>   void kvm_mmu_module_exit(void);
>   
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 412646b973bb..1bea616402e6 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8264,43 +8264,12 @@ static void kvm_timer_init(void)
>   			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
>   }
>   
> -static inline bool kvm_pmi_in_guest(struct kvm_vcpu *vcpu)
> -{
> -	return vcpu && vcpu->arch.handling_intr_from_guest;
> -}
> -
> -static unsigned int kvm_guest_state(void)
> -{
> -	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> -	unsigned int state;
> -
> -	if (!kvm_pmi_in_guest(vcpu))
> -		return 0;
> -
> -	state = PERF_GUEST_ACTIVE;
> -	if (static_call(kvm_x86_get_cpl)(vcpu))
> -		state |= PERF_GUEST_USER;
> -
> -	return state;
> -}
> -
> -static unsigned long kvm_guest_get_ip(void)
> -{
> -	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> -
> -	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
> -	if (WARN_ON_ONCE(!kvm_pmi_in_guest(vcpu)))
> -		return 0;
> -
> -	return kvm_rip_read(vcpu);
> -}
> -
>   static unsigned int kvm_handle_intel_pt_intr(void)
>   {
>   	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
>   
>   	/* '0' on failure so that the !PT case can use a RET0 static call. */
> -	if (!kvm_pmi_in_guest(vcpu))
> +	if (!kvm_arch_pmi_in_guest(vcpu))
>   		return 0;
>   
>   	kvm_make_request(KVM_REQ_PMI, vcpu);
> @@ -8309,12 +8278,6 @@ static unsigned int kvm_handle_intel_pt_intr(void)
>   	return 1;
>   }
>   
> -static struct perf_guest_info_callbacks kvm_guest_cbs = {
> -	.state			= kvm_guest_state,
> -	.get_ip			= kvm_guest_get_ip,
> -	.handle_intel_pt_intr	= NULL,
> -};
> -
>   #ifdef CONFIG_X86_64
>   static void pvclock_gtod_update_fn(struct work_struct *work)
>   {
> @@ -11068,9 +11031,11 @@ int kvm_arch_hardware_setup(void *opaque)
>   	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
>   	kvm_ops_static_call_update();
>   
> +	/* Temporary ugliness. */
>   	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
> -		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
> -	perf_register_guest_info_callbacks(&kvm_guest_cbs);
> +		kvm_register_perf_callbacks(kvm_handle_intel_pt_intr);
> +	else
> +		kvm_register_perf_callbacks(NULL);
>   
>   	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
>   		supported_xss = 0;
> @@ -11099,8 +11064,7 @@ int kvm_arch_hardware_setup(void *opaque)
>   
>   void kvm_arch_hardware_unsetup(void)
>   {
> -	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
> -	kvm_guest_cbs.handle_intel_pt_intr = NULL;
> +	kvm_unregister_perf_callbacks();
>   
>   	static_call(kvm_x86_hardware_unsetup)();
>   }
> @@ -11727,6 +11691,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
>   	return vcpu->arch.preempted_in_kernel;
>   }
>   
> +unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
> +{
> +	return kvm_rip_read(vcpu);
> +}
> +
>   int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
>   {
>   	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index e4d712e9f760..b9255a6439f2 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1163,6 +1163,16 @@ static inline bool kvm_arch_intc_initialized(struct kvm *kvm)
>   }
>   #endif
>   
> +#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_unregister_perf_callbacks(void);
> +#else
> +static inline void kvm_register_perf_callbacks(void *ign) {}
> +static inline void kvm_unregister_perf_callbacks(void) {}
> +#endif /* CONFIG_GUEST_PERF_EVENTS */
> +
>   int kvm_arch_init_vm(struct kvm *kvm, unsigned long type);
>   void kvm_arch_destroy_vm(struct kvm *kvm);
>   void kvm_arch_sync_events(struct kvm *kvm);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 3e67c93ca403..179fb110a00f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -5460,6 +5460,50 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
>           return &kvm_running_vcpu;
>   }
>   
> +#ifdef CONFIG_GUEST_PERF_EVENTS
> +static unsigned int kvm_guest_state(void)
> +{
> +	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> +	unsigned int state;
> +
> +	if (!kvm_arch_pmi_in_guest(vcpu))
> +		return 0;
> +
> +	state = PERF_GUEST_ACTIVE;
> +	if (!kvm_arch_vcpu_in_kernel(vcpu))
> +		state |= PERF_GUEST_USER;
> +
> +	return state;
> +}
> +
> +static unsigned long kvm_guest_get_ip(void)
> +{
> +	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> +
> +	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
> +	if (WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)))
> +		return 0;
> +
> +	return kvm_arch_vcpu_get_ip(vcpu);
> +}
> +
> +static struct perf_guest_info_callbacks kvm_guest_cbs = {
> +	.state			= kvm_guest_state,
> +	.get_ip			= kvm_guest_get_ip,
> +	.handle_intel_pt_intr	= NULL,
> +};
> +
> +void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
> +{
> +	kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
> +	perf_register_guest_info_callbacks(&kvm_guest_cbs);
> +}
> +void kvm_unregister_perf_callbacks(void)
> +{
> +	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
> +}
> +#endif
> +
>   struct kvm_cpu_compat_check {
>   	void *opaque;
>   	int *ret;
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

On Wed, 22 Sep 2021 01:05:29 +0100,
Sean Christopherson <seanjc@google.com> wrote:
> 
> Move x86's perf guest callbacks into common KVM, as they are semantically
> identical to arm64's callbacks (the only other such KVM callbacks).
> arm64 will convert to the common versions in a future patch.
> 
> Implement the necessary arm64 arch hooks now to avoid having to provide
> stubs or a temporary #define (from x86) to avoid arm64 compilation errors
> when CONFIG_GUEST_PERF_EVENTS=y.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/arm64/include/asm/kvm_host.h |  8 +++++
>  arch/arm64/kvm/arm.c              |  5 +++
>  arch/x86/include/asm/kvm_host.h   |  3 ++
>  arch/x86/kvm/x86.c                | 53 +++++++------------------------
>  include/linux/kvm_host.h          | 10 ++++++
>  virt/kvm/kvm_main.c               | 44 +++++++++++++++++++++++++
>  6 files changed, 81 insertions(+), 42 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index ed940aec89e0..828b6eaa2c56 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -673,6 +673,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
>  void kvm_perf_init(void);
>  void kvm_perf_teardown(void);
>  
> +#ifdef CONFIG_GUEST_PERF_EVENTS
> +static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)

Pardon my x86 ignorance, what is PMI? PMU Interrupt?

> +{
> +	/* Any callback while a vCPU is loaded is considered to be in guest. */
> +	return !!vcpu;
> +}
> +#endif

Do you really need this #ifdef?

> +
>  long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
>  gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
>  void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index e9a2b8f27792..2b542fdc237e 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -500,6 +500,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
>  	return vcpu_mode_priv(vcpu);
>  }
>  
> +unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
> +{
> +	return *vcpu_pc(vcpu);
> +}
> +
>  /* Just ensure a guest exit from a particular CPU */
>  static void exit_vm_noop(void *info)
>  {

The above nits notwithstanding,

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

On Mon, Oct 11, 2021, Marc Zyngier wrote:
> On Wed, 22 Sep 2021 01:05:29 +0100, Sean Christopherson <seanjc@google.com> wrote:
> > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> > index ed940aec89e0..828b6eaa2c56 100644
> > --- a/arch/arm64/include/asm/kvm_host.h
> > +++ b/arch/arm64/include/asm/kvm_host.h
> > @@ -673,6 +673,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
> >  void kvm_perf_init(void);
> >  void kvm_perf_teardown(void);
> >  
> > +#ifdef CONFIG_GUEST_PERF_EVENTS
> > +static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
> 
> Pardon my x86 ignorance, what is PMI? PMU Interrupt?

Ya, Performance Monitoring Interrupt.  I didn't realize the term wasn't common
perf terminology.  Maybe kvm_arch_perf_events_in_guest() to be less x86-centric?

> > +{
> > +	/* Any callback while a vCPU is loaded is considered to be in guest. */
> > +	return !!vcpu;
> > +}
> > +#endif
> 
> Do you really need this #ifdef?

Nope, should compile fine without it, though simply dropping the #ifdef would make
make the semantics of the function wrong, even if nothing consumes it.  Tweak it
to use IS_ENABLED()?

	return IS_ENABLED(CONFIG_GUEST_PERF_EVENTS) && !!vcpu;

On Mon, 11 Oct 2021 15:46:25 +0100,
Sean Christopherson <seanjc@google.com> wrote:
> 
> On Mon, Oct 11, 2021, Marc Zyngier wrote:
> > On Wed, 22 Sep 2021 01:05:29 +0100, Sean Christopherson <seanjc@google.com> wrote:
> > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> > > index ed940aec89e0..828b6eaa2c56 100644
> > > --- a/arch/arm64/include/asm/kvm_host.h
> > > +++ b/arch/arm64/include/asm/kvm_host.h
> > > @@ -673,6 +673,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
> > >  void kvm_perf_init(void);
> > >  void kvm_perf_teardown(void);
> > >  
> > > +#ifdef CONFIG_GUEST_PERF_EVENTS
> > > +static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
> > 
> > Pardon my x86 ignorance, what is PMI? PMU Interrupt?
> 
> Ya, Performance Monitoring Interrupt.  I didn't realize the term wasn't
> common perf terminology.  Maybe kvm_arch_perf_events_in_guest() to be
> less x86-centric?

Up to you. I would be happy with just a comment.

> 
> > > +{
> > > +	/* Any callback while a vCPU is loaded is considered to be in guest. */
> > > +	return !!vcpu;
> > > +}
> > > +#endif
> > 
> > Do you really need this #ifdef?
> 
> Nope, should compile fine without it, though simply dropping the #ifdef
> would make make the semantics of the function wrong, even if nothing
> consumes it.  Tweak it to use IS_ENABLED()?
> 
> 	return IS_ENABLED(CONFIG_GUEST_PERF_EVENTS) && !!vcpu;

LGTM.

	M.

-- 
Without deviation from the norm, progress is not possible.