[PATCH 21/24] selftests/resctrl: Get resource id from cache id

[Ilpo Järvinen]

Resource id is acquired differently depending on CPU. AMD tests use id
from L3 cache, whereas CPUs from other vendors base the id on topology
package id. In order to support L2 CAT test, this has to be
generalized.

The driver side code seems to get the resource ids from cache ids so
the approach used by the AMD branch seems to match the kernel-side
code. It will also work with L2 resource IDs as long as the cache level
is generalized.

Using the topology id was always fragile due to mismatch with the
kernel-side way to acquire the resource id. It got incorrect resource
id, e.g., when Cluster-on-Die (CoD) is enabled for CPU (but CoD is not
well suited for resctrl in the first place so it has not been a big
issues if test don't work correctly with it).

Taking all the above into account, generalize the resource id
calculation by taking it from the cache id and do not hard-code the
cache level.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
 tools/testing/selftests/resctrl/resctrl.h     |  2 +-
 tools/testing/selftests/resctrl/resctrl_val.c |  4 +--
 tools/testing/selftests/resctrl/resctrlfs.c   | 31 ++++++++++++-------
 3 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 99fbce4794bc..c148998bf6ad 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -121,7 +121,7 @@ extern char llc_occup_path[1024];
 int get_vendor(void);
 bool check_resctrlfs_support(void);
 int filter_dmesg(void);
-int get_resource_id(int cpu_no, int *resource_id);
+int get_resource_id(const char *resource, int cpu_no, int *resource_id);
 int mount_resctrlfs(void);
 int umount_resctrlfs(void);
 int validate_bw_report_request(char *bw_report);
diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index 43ca026c6e0f..d210daafc5af 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -415,7 +415,7 @@ static void initialize_mem_bw_resctrl(const char *ctrlgrp, const char *mongrp,
 {
 	int resource_id;
 
-	if (get_resource_id(cpu_no, &resource_id) < 0) {
+	if (get_resource_id("MB", cpu_no, &resource_id) < 0) {
 		perror("Could not get resource_id");
 		return;
 	}
@@ -584,7 +584,7 @@ static void initialize_llc_occu_resctrl(const char *ctrlgrp, const char *mongrp,
 {
 	int resource_id;
 
-	if (get_resource_id(cpu_no, &resource_id) < 0) {
+	if (get_resource_id("L3", cpu_no, &resource_id) < 0) {
 		perror("# Unable to resource_id");
 		return;
 	}
diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
index b98d88f7cbc4..8e79b646d7cb 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -111,24 +111,33 @@ static int get_cache_level(const char *cache_type)
 	return -1;
 }
 
+static int get_resource_cache_level(const char *resource)
+{
+	/* "MB" use L3 (LLC) resource id */
+	if (!strcmp(resource, "MB"))
+		return 3;
+	return get_cache_level(resource);
+}
+
 /*
- * get_resource_id - Get socket number/l3 id for a specified CPU
- * @cpu_no:	CPU number
- * @resource_id: Socket number or l3_id
+ * get_resource_id - Get resctrl resource id for a specified CPU
+ * @resource:		resource
+ * @cpu_no:		CPU number
+ * @resource_id:	resource id (cache id; for MB, L3 cache id)
  *
  * Return: >= 0 on success, < 0 on failure.
  */
-int get_resource_id(int cpu_no, int *resource_id)
+int get_resource_id(const char *resource, int cpu_no, int *resource_id)
 {
 	char phys_pkg_path[1024];
+	int cache_num;
 	FILE *fp;
 
-	if (get_vendor() == ARCH_AMD)
-		sprintf(phys_pkg_path, "%s%d/cache/index3/id",
-			PHYS_ID_PATH, cpu_no);
-	else
-		sprintf(phys_pkg_path, "%s%d/topology/physical_package_id",
-			PHYS_ID_PATH, cpu_no);
+	cache_num = get_resource_cache_level(resource);
+	if (cache_num < 0)
+		return cache_num;
+
+	sprintf(phys_pkg_path, "%s%d/cache/index%d/id", PHYS_ID_PATH, cpu_no, cache_num);
 
 	fp = fopen(phys_pkg_path, "r");
 	if (!fp) {
@@ -526,7 +535,7 @@ int write_schemata(char *ctrlgrp, char *schemata, int cpu_no, const char *resour
 		return -1;
 	}
 
-	if (get_resource_id(cpu_no, &resource_id) < 0) {
+	if (get_resource_id(resource, cpu_no, &resource_id) < 0) {
 		sprintf(reason, "Failed to get resource id");
 		ret = -1;
 
-- 
2.30.2