[PATCH v2 4/5] KVM: selftests: Add an interface to read the data of named vcpu stat

[Manali Shukla <manali.shukla@amd.com>]

From: Manali Shukla <Manali.Shukla@amd.com>

The interface is used to read the data values of a specified vcpu stat
from the currenly available binary stats interface.

Signed-off-by: Manali Shukla <Manali.Shukla@amd.com>
---
 .../testing/selftests/kvm/include/kvm_util.h  | 66 +++++++++++++++++++
 tools/testing/selftests/kvm/lib/kvm_util.c    | 32 +++++++++
 2 files changed, 98 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 63c2aaae51f3..7dad3275a4d3 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -518,6 +518,72 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name)
 	return data;
 }
 
+/*
+ * Ensure that the sequence of the enum vcpu_stat_types matches the order of
+ * kvm_vcpu_stats_desc[].  Otherwise, vcpu_get_stat() may return incorrect data
+ * because __vcpu_get_stat() uses the enum type as an index to get the
+ * descriptor for a given stat and then uses read_stat_data() to get the stats
+ * from the descriptor.
+ */
+enum vcpu_stat_types {
+	HALT_SUCCESSFUL_POLL,
+	HALT_ATTEMPTED_POLL,
+	HALT_POLL_INVALID,
+	HALT_WAKEUP,
+	HALT_POLL_SUCCESS_NS,
+	HALT_POLL_FAIL_NS,
+	HALT_WAIT_NS,
+	HALT_POLL_SUCCESS_HIST,
+	HALT_POLL_FAIL_HIST,
+	HALT_WAIT_HIST,
+	BLOCKING,
+	PF_TAKEN,
+	PF_FIXED,
+	PF_EMULATE,
+	PF_SPURIOUS,
+	PF_FAST,
+	PF_MMIO_SPTE_CREATED,
+	PF_GUEST,
+	TLB_FLUSH,
+	INVLPG,
+	EXITS,
+	IO_EXITS,
+	MMIO_EXITS,
+	SIGNAL_EXITS,
+	IRQ_WINDOW_EXITS,
+	NMI_WINDOW_EXITS,
+	LD_FLUSH,
+	HALT_EXITS,
+	REQUEST_IRQ_EXITS,
+	IRQ_EXITS,
+	HOST_STATE_RELOAD,
+	FPU_RELOAD,
+	INSN_EMULATION,
+	INSN_EMULATION_FAIL,
+	HYPERCALLS,
+	IRQ_INJECTIONS,
+	NMI_INJECTIONS,
+	REQ_EVENT,
+	NESTED_RUN,
+	DIRECTED_YIELD_ATTEMPTED,
+	DIRECTED_YIELD_SUCCESSFUL,
+	PREEMPTION_REPORTED,
+	PREEMPTION_OTHER,
+	GUEST_MODE,
+	NOTIFY_WINDOW_EXITS,
+};
+
+void __vcpu_get_stat(struct kvm_vcpu *vcpu, enum vcpu_stat_types type, uint64_t *data,
+		   size_t max_elements);
+
+static inline uint64_t vcpu_get_stat(struct kvm_vcpu *vcpu, enum vcpu_stat_types type)
+{
+	uint64_t data;
+
+	__vcpu_get_stat(vcpu, type, &data, 1);
+	return data;
+}
+
 void vm_create_irqchip(struct kvm_vm *vm);
 
 static inline int __vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 6b2158655baa..3de292ca9280 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -2256,6 +2256,38 @@ void read_stat_data(int stats_fd, struct kvm_stats_header *header,
 		    desc->name, size, ret);
 }
 
+/*
+ * Read the data of the named vcpu stat
+ *
+ * Input Args:
+ *   vcpu - the vcpu for which the stat should be read
+ *   stat_name - the name of the stat to read
+ *   max_elements - the maximum number of 8-byte values to read into data
+ *
+ * Output Args:
+ *   data - the buffer into which stat data should be read
+ *
+ * Read the data values of a specified stat from the binary stats interface.
+ */
+void __vcpu_get_stat(struct kvm_vcpu *vcpu, enum vcpu_stat_types type, uint64_t *data,
+		   size_t max_elements)
+{
+	int vcpu_stats_fd;
+	struct kvm_stats_header header;
+	struct kvm_stats_desc *desc, *t_desc;
+	size_t size_desc;
+
+	vcpu_stats_fd = vcpu_get_stats_fd(vcpu);
+	read_stats_header(vcpu_stats_fd, &header);
+
+	desc = read_stats_descriptors(vcpu_stats_fd, &header);
+	size_desc = get_stats_descriptor_size(&header);
+
+	t_desc = (void *)desc + (type * size_desc);
+	read_stat_data(vcpu_stats_fd, &header, t_desc,
+			data, max_elements);
+}
+
 /*
  * Read the data of the named stat
  *
-- 
2.34.1