[PATCH 11/12] xen/hypfs: add scheduling granularity entry to cpupool entries

From: Juergen Gross <jgross@suse.com>
To: xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Ian Jackson <iwj@xenproject.org>, Jan Beulich <jbeulich@suse.com>,
	Julien Grall <julien@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
	Dario Faggioli <dfaggioli@suse.com>
Subject: [PATCH 11/12] xen/hypfs: add scheduling granularity entry to cpupool entries
Date: Mon, 26 Oct 2020 10:13:15 +0100	[thread overview]
Message-ID: <20201026091316.25680-12-jgross@suse.com> (raw)
In-Reply-To: <20201026091316.25680-1-jgross@suse.com>

Add a "sched-gran" entry to the per-cpupool hypfs directories.

For now make this entry read-only and let it contain one of the
strings "cpu", "core" or "socket".

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 docs/misc/hypfs-paths.pandoc |  4 +++
 xen/common/sched/cpupool.c   | 51 +++++++++++++++++++++++++++++++++---
 2 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/docs/misc/hypfs-paths.pandoc b/docs/misc/hypfs-paths.pandoc
index aaca1cdf92..f1ce24d7fe 100644
--- a/docs/misc/hypfs-paths.pandoc
+++ b/docs/misc/hypfs-paths.pandoc
@@ -184,6 +184,10 @@ A directory of all current cpupools.
 The individual cpupools. Each entry is a directory with the name being the
 cpupool-id (e.g. /cpupool/0/).
 
+#### /cpupool/*/sched-gran = ("cpu" | "core" | "socket")
+
+The scheduling granularity of a cpupool.
+
 #### /params/
 
 A directory of runtime parameters.
diff --git a/xen/common/sched/cpupool.c b/xen/common/sched/cpupool.c
index 8612ee5cf6..8674ac0fdd 100644
--- a/xen/common/sched/cpupool.c
+++ b/xen/common/sched/cpupool.c
@@ -42,9 +42,10 @@ static DEFINE_SPINLOCK(cpupool_lock);
 static enum sched_gran __read_mostly opt_sched_granularity = SCHED_GRAN_cpu;
 static unsigned int __read_mostly sched_granularity = 1;
 
+#define SCHED_GRAN_NAME_LEN  8
 struct sched_gran_name {
     enum sched_gran mode;
-    char name[8];
+    char name[SCHED_GRAN_NAME_LEN];
 };
 
 static const struct sched_gran_name sg_name[] = {
@@ -53,7 +54,7 @@ static const struct sched_gran_name sg_name[] = {
     {SCHED_GRAN_socket, "socket"},
 };
 
-static void sched_gran_print(enum sched_gran mode, unsigned int gran)
+static const char *sched_gran_get_name(enum sched_gran mode)
 {
     const char *name = "";
     unsigned int i;
@@ -67,8 +68,13 @@ static void sched_gran_print(enum sched_gran mode, unsigned int gran)
         }
     }
 
+    return name;
+}
+
+static void sched_gran_print(enum sched_gran mode, unsigned int gran)
+{
     printk("Scheduling granularity: %s, %u CPU%s per sched-resource\n",
-           name, gran, gran == 1 ? "" : "s");
+           sched_gran_get_name(mode), gran, gran == 1 ? "" : "s");
 }
 
 #ifdef CONFIG_HAS_SCHED_GRANULARITY
@@ -1057,6 +1063,43 @@ static struct hypfs_entry *cpupool_dir_findentry(struct hypfs_entry_dir *dir,
     return hypfs_gen_dyndir_entry_id(&cpupool_pooldir, id);
 }
 
+static int cpupool_gran_read(const struct hypfs_entry *entry,
+                             XEN_GUEST_HANDLE_PARAM(void) uaddr)
+{
+    const struct hypfs_dyndir_id *data;
+    struct cpupool *cpupool;
+    const char *name = "";
+
+    data = hypfs_get_dyndata();
+    if ( !data )
+        return -ENOENT;
+
+    spin_lock(&cpupool_lock);
+
+    cpupool = __cpupool_find_by_id(data->id, true);
+    if ( cpupool )
+        name = sched_gran_get_name(cpupool->gran);
+
+    spin_unlock(&cpupool_lock);
+
+    if ( !cpupool )
+        return -ENOENT;
+
+    return copy_to_guest(uaddr, name, strlen(name) + 1) ? -EFAULT : 0;
+}
+
+static struct hypfs_funcs cpupool_gran_funcs = {
+    .read = cpupool_gran_read,
+    .getsize = hypfs_getsize,
+};
+
+static HYPFS_VARSIZE_INIT(cpupool_gran, XEN_HYPFS_TYPE_STRING, "sched-gran",
+                          0, &cpupool_gran_funcs);
+static char granstr[SCHED_GRAN_NAME_LEN] = {
+    [0 ... SCHED_GRAN_NAME_LEN - 2] = '?',
+    [SCHED_GRAN_NAME_LEN - 1] = 0
+};
+
 static struct hypfs_funcs cpupool_dir_funcs = {
     .read = cpupool_dir_read,
     .getsize = cpupool_dir_getsize,
@@ -1075,6 +1118,8 @@ static int __init cpupool_init(void)
 
 #ifdef CONFIG_HYPFS
     hypfs_add_dir(&hypfs_root, &cpupool_dir, true);
+    hypfs_string_set_reference(&cpupool_gran, granstr);
+    hypfs_add_leaf(&cpupool_pooldir, &cpupool_gran, true);
 #endif
 
     cpupool0 = cpupool_create(0, 0, &err);
-- 
2.26.2


