linux-kernel - [PATCH kvm-unit-tests] x86/pmu: Add Intel Guest Transactional (commited) cycles testcase

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Message-Id: <20221207071506.15733-1-likexu@tencent.com>
Date:   Wed,  7 Dec 2022 15:15:05 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH kvm-unit-tests] x86/pmu: Add Intel Guest Transactional (commited) cycles testcase

From: Like Xu <likexu@...cent.com>

On Intel platforms with TSX feature, pmu users in guest can collect
the commited or total transactional cycles for a tsx-enabled workload,
adding new test cases to cover them, as they are not strictly the same
as normal hardware events from the KVM implementation point of view.

Signed-off-by: Like Xu <likexu@...cent.com>
---
 x86/pmu.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

diff --git a/x86/pmu.c b/x86/pmu.c
index 72c2c9c..d4c6813 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -20,7 +20,7 @@
 
 typedef struct {
 	uint32_t ctr;
-	uint32_t config;
+	uint64_t config;
 	uint64_t count;
 	int idx;
 } pmu_counter_t;
@@ -547,6 +547,76 @@ static void check_emulated_instr(void)
 	report_prefix_pop();
 }
 
+#define _XBEGIN_STARTED		(~0u)
+
+static inline int _xbegin(void)
+{
+	int ret = _XBEGIN_STARTED;
+	asm volatile(".byte 0xc7,0xf8 ; .long 0" : "+a" (ret) :: "memory");
+	return ret;
+}
+
+static inline void _xend(void)
+{
+	asm volatile(".byte 0x0f,0x01,0xd5" ::: "memory");
+}
+
+int *ptr;
+
+static void tsx_fault(void)
+{
+	int value = 0;
+
+	ptr = NULL;
+	if(_xbegin() == _XBEGIN_STARTED) {
+		value++;
+		// causes abort
+		*ptr = value;
+		_xend();
+	}
+}
+
+static void tsx_normal(void)
+{
+	int value = 0;
+
+	if(_xbegin() == _XBEGIN_STARTED) {
+		value++;
+		_xend();
+	}
+}
+
+static void check_tsx_cycles(void)
+{
+	pmu_counter_t cnt;
+	int i;
+
+	if (!this_cpu_has(X86_FEATURE_RTM) || !this_cpu_has(X86_FEATURE_HLE))
+		return;
+
+	report_prefix_push("TSX cycles");
+
+	for (i = 0; i < pmu.nr_gp_counters; i++) {
+		cnt.ctr = MSR_GP_COUNTERx(i);
+
+		if (i == 2)
+			/* Transactional cycles commited only on gp counter 2 */
+			cnt.config = EVNTSEL_OS | EVNTSEL_USR | 0x30000003c;
+		else
+			/* Transactional cycles */
+			cnt.config = EVNTSEL_OS | EVNTSEL_USR | 0x10000003c;
+
+		start_event(&cnt);
+		tsx_fault();
+		tsx_normal();
+		stop_event(&cnt);
+
+		report(cnt.count > 0, "gp cntr-%d", i);
+	}
+
+	report_prefix_pop();
+}
+
 static void check_counters(void)
 {
 	if (is_fep_available())
@@ -559,6 +629,7 @@ static void check_counters(void)
 	check_counter_overflow();
 	check_gp_counter_cmask();
 	check_running_counter_wrmsr();
+	check_tsx_cycles();
 }
 
 static void do_unsupported_width_counter_write(void *index)
-- 
2.38.1