perf/x86/core: Pass "struct kvm_pmu *" to determine the guest values

Splitting the logic for determining the guest values is unnecessarily
confusing, and potentially fragile. Perf should have full knowledge and
control of what values are loaded for the guest.

If we change .guest_get_msrs() to take a struct kvm_pmu pointer, then it
can generate the full set of guest values by grabbing guest ds_area and
pebs_data_cfg. Alternatively, .guest_get_msrs() could take the desired
guest MSR values directly (ds_area and pebs_data_cfg), but kvm_pmu is
vendor agnostic, so we don't see any reason to not just pass the pointer.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-Id: <20220411101946.20262-4-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/events/core.c

@@ -693,9 +693,9 @@ void x86_pmu_disable_all(void)
 	}
 }
 
-struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
+struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, void *data)
 {
-	return static_call(x86_pmu_guest_get_msrs)(nr);
+	return static_call(x86_pmu_guest_get_msrs)(nr, data);
 }
 EXPORT_SYMBOL_GPL(perf_guest_get_msrs);
 

arch/x86/events/intel/core.c

@@ -3972,7 +3972,7 @@ static int intel_pmu_hw_config(struct perf_event *event)
 	return 0;
 }
 
-static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
+static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr, void *data)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	struct perf_guest_switch_msr *arr = cpuc->guest_switch_msrs;
@@ -4005,7 +4005,7 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
 	return arr;
 }
 
-static struct perf_guest_switch_msr *core_guest_get_msrs(int *nr)
+static struct perf_guest_switch_msr *core_guest_get_msrs(int *nr, void *data)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	struct perf_guest_switch_msr *arr = cpuc->guest_switch_msrs;

arch/x86/events/perf_event.h

@@ -903,7 +903,7 @@ struct x86_pmu {
 	/*
 	 * Intel host/guest support (KVM)
 	 */
-	struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr);
+	struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr, void *data);
 
 	/*
 	 * Check period value for PERF_EVENT_IOC_PERIOD ioctl.

arch/x86/include/asm/perf_event.h

@@ -519,10 +519,10 @@ static inline void perf_check_microcode(void) { }
 #endif
 
 #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
-extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, void *data);
 extern int x86_perf_get_lbr(struct x86_pmu_lbr *lbr);
 #else
-struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, void *data);
 static inline int x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
 {
 	return -1;

arch/x86/kvm/vmx/vmx.c

@@ -6794,9 +6794,10 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
 {
 	int i, nr_msrs;
 	struct perf_guest_switch_msr *msrs;
+	struct kvm_pmu *pmu = vcpu_to_pmu(&vmx->vcpu);
 
 	/* Note, nr_msrs may be garbage if perf_guest_get_msrs() returns NULL. */
-	msrs = perf_guest_get_msrs(&nr_msrs);
+	msrs = perf_guest_get_msrs(&nr_msrs, (void *)pmu);
 	if (!msrs)
 		return;