[PATCH v5 03/10] KVM: selftests: Read binary stats desc in lib

[Ben Gardon <bgardon@google.com>]

Move the code to read the binary stats descriptors to the KVM selftests
library. It will be re-used by other tests to check KVM behavior.

No functional change intended.

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 .../selftests/kvm/include/kvm_util_base.h     |  2 +
 .../selftests/kvm/kvm_binary_stats_test.c     |  8 +---
 tools/testing/selftests/kvm/lib/kvm_util.c    | 38 +++++++++++++++++++
 3 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 749cded9b157..fabe46ddc1b2 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -401,6 +401,8 @@ void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid);
 int vm_get_stats_fd(struct kvm_vm *vm);
 int vcpu_get_stats_fd(struct kvm_vm *vm, uint32_t vcpuid);
 void read_stats_header(int stats_fd, struct kvm_stats_header *header);
+struct kvm_stats_desc *read_stats_desc(int stats_fd,
+				       struct kvm_stats_header *header);
 
 uint32_t guest_get_vcpuid(void);
 
diff --git a/tools/testing/selftests/kvm/kvm_binary_stats_test.c b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
index fb511b42a03e..b49fae45db1e 100644
--- a/tools/testing/selftests/kvm/kvm_binary_stats_test.c
+++ b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
@@ -62,14 +62,8 @@ static void stats_test(int stats_fd)
 							header.data_offset),
 			"Descriptor block is overlapped with data block");
 
-	/* Allocate memory for stats descriptors */
-	stats_desc = calloc(header.num_desc, size_desc);
-	TEST_ASSERT(stats_desc, "Allocate memory for stats descriptors");
 	/* Read kvm stats descriptors */
-	ret = pread(stats_fd, stats_desc,
-			size_desc * header.num_desc, header.desc_offset);
-	TEST_ASSERT(ret == size_desc * header.num_desc,
-			"Read KVM stats descriptors");
+	stats_desc = read_stats_desc(stats_fd, &header);
 
 	/* Sanity check for fields in descriptors */
 	for (i = 0; i < header.num_desc; ++i) {
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 1d75d41f92dc..12fa8cc88043 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -2577,3 +2577,41 @@ void read_stats_header(int stats_fd, struct kvm_stats_header *header)
 	ret = read(stats_fd, header, sizeof(*header));
 	TEST_ASSERT(ret == sizeof(*header), "Read stats header");
 }
+
+static ssize_t stats_descs_size(struct kvm_stats_header *header)
+{
+	return header->num_desc *
+	       (sizeof(struct kvm_stats_desc) + header->name_size);
+}
+
+/*
+ * Read binary stats descriptors
+ *
+ * Input Args:
+ *   stats_fd - the file descriptor for the binary stats file from which to read
+ *   header - the binary stats metadata header corresponding to the given FD
+ *
+ * Output Args: None
+ *
+ * Return:
+ *   A pointer to a newly allocated series of stat descriptors.
+ *   Caller is responsible for freeing the returned kvm_stats_desc.
+ *
+ * Read the stats descriptors from the binary stats interface.
+ */
+struct kvm_stats_desc *read_stats_desc(int stats_fd,
+				       struct kvm_stats_header *header)
+{
+	struct kvm_stats_desc *stats_desc;
+	ssize_t ret;
+
+	stats_desc = malloc(stats_descs_size(header));
+	TEST_ASSERT(stats_desc, "Allocate memory for stats descriptors");
+
+	ret = pread(stats_fd, stats_desc, stats_descs_size(header),
+		    header->desc_offset);
+	TEST_ASSERT(ret == stats_descs_size(header),
+		    "Read KVM stats descriptors");
+
+	return stats_desc;
+}
-- 
2.35.1.1178.g4f1659d476-goog