linux-kernel - [kvm-unit-tests Patch v3 08/11] x86: pmu: Improve instruction and branches events verification

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Date: Wed,  3 Jan 2024 11:14:06 +0800
From: Dapeng Mi <dapeng1.mi@...ux.intel.com>
To: Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Jim Mattson <jmattson@...gle.com>
Cc: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Zhenyu Wang <zhenyuw@...ux.intel.com>,
	Zhang Xiong <xiong.y.zhang@...el.com>,
	Mingwei Zhang <mizhang@...gle.com>,
	Like Xu <like.xu.linux@...il.com>,
	Jinrong Liang <cloudliang@...cent.com>,
	Dapeng Mi <dapeng1.mi@...el.com>,
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: [kvm-unit-tests Patch v3 08/11] x86: pmu: Improve instruction and branches events verification

If HW supports GLOBAL_CTRL MSR, enabling and disabling PMCs are moved in
__precise_count_loop(). Thus, instructions and branches events can be
verified against a precise count instead of a rough range.

Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
---
 x86/pmu.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/x86/pmu.c b/x86/pmu.c
index 88b89ad889b9..b764827c1c3d 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -25,6 +25,10 @@
 	"nop; nop; nop; nop; nop; nop; nop;\n\t"	\
 	"loop 1b;\n\t"
 
+/*Enable GLOBAL_CTRL + disable GLOBAL_CTRL instructions */
+#define PRECISE_EXTRA_INSTRNS  (2 + 4)
+#define PRECISE_LOOP_INSTRNS   (N * LOOP_INSTRNS + PRECISE_EXTRA_INSTRNS)
+#define PRECISE_LOOP_BRANCHES  (N)
 #define PRECISE_LOOP_ASM						\
 	"wrmsr;\n\t"							\
 	"mov %%ecx, %%edi; mov %%ebx, %%ecx;\n\t"			\
@@ -107,6 +111,24 @@ static inline void loop(u64 cntrs)
 		__precise_count_loop(cntrs);
 }
 
+static void adjust_events_range(struct pmu_event *gp_events, int branch_idx)
+{
+	/*
+	 * If HW supports GLOBAL_CTRL MSR, enabling and disabling PMCs are
+	 * moved in __precise_count_loop(). Thus, instructions and branches
+	 * events can be verified against a precise count instead of a rough
+	 * range.
+	 */
+	if (this_cpu_has_perf_global_ctrl()) {
+		/* instructions event */
+		gp_events[0].min = PRECISE_LOOP_INSTRNS;
+		gp_events[0].max = PRECISE_LOOP_INSTRNS;
+		/* branches event */
+		gp_events[branch_idx].min = PRECISE_LOOP_BRANCHES;
+		gp_events[branch_idx].max = PRECISE_LOOP_BRANCHES;
+	}
+}
+
 volatile uint64_t irq_received;
 
 static void cnt_overflow(isr_regs_t *regs)
@@ -771,6 +793,7 @@ static void check_invalid_rdpmc_gp(void)
 
 int main(int ac, char **av)
 {
+	int branch_idx;
 	setup_vm();
 	handle_irq(PMI_VECTOR, cnt_overflow);
 	buf = malloc(N*64);
@@ -784,13 +807,16 @@ int main(int ac, char **av)
 		}
 		gp_events = (struct pmu_event *)intel_gp_events;
 		gp_events_size = sizeof(intel_gp_events)/sizeof(intel_gp_events[0]);
+		branch_idx = 5;
 		report_prefix_push("Intel");
 		set_ref_cycle_expectations();
 	} else {
 		gp_events_size = sizeof(amd_gp_events)/sizeof(amd_gp_events[0]);
 		gp_events = (struct pmu_event *)amd_gp_events;
+		branch_idx = 2;
 		report_prefix_push("AMD");
 	}
+	adjust_events_range(gp_events, branch_idx);
 
 	printf("PMU version:         %d\n", pmu.version);
 	printf("GP counters:         %d\n", pmu.nr_gp_counters);
-- 
2.34.1