[Xen-devel] [PATCH v4 05/12] x86: maintain socket CPU mask for CAT

[Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>]

Some CAT resource/registers exist in socket level and they must be
accessed from the CPU of the corresponding socket. It's common to pick
an arbitrary CPU from the socket. To make the picking easy, it's useful
to maintain a reference to the cpu_core_mask which contains all the
siblings of a CPU in the same socket. The reference needs to be
synchronized with the CPU up/down.

Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/psr.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index 4aff5f6..7de2504 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -32,6 +32,7 @@ struct psr_cat_socket_info {
     unsigned int cbm_len;
     unsigned int cos_max;
     struct psr_cat_cbm *cos_cbm_map;
+    cpumask_t *socket_cpu_mask;
 };
 
 struct psr_assoc {
@@ -234,6 +235,8 @@ static void cat_cpu_init(unsigned int cpu)
     ASSERT(socket < nr_sockets);
 
     info = cat_socket_info + socket;
+    if ( info->socket_cpu_mask == NULL )
+        info->socket_cpu_mask = per_cpu(cpu_core_mask, cpu);
 
     /* Avoid initializing more than one times for the same socket. */
     if ( test_and_set_bool(info->initialized) )
@@ -274,6 +277,24 @@ static void psr_cpu_init(unsigned int cpu)
     psr_assoc_init(cpu);
 }
 
+static void psr_cpu_fini(unsigned int cpu)
+{
+    unsigned int socket, next;
+    cpumask_t *cpu_mask;
+
+    if ( cat_socket_info )
+    {
+        socket = cpu_to_socket(cpu);
+        cpu_mask = cat_socket_info[socket].socket_cpu_mask;
+
+        if ( (next = cpumask_cycle(cpu, cpu_mask)) == cpu )
+            cat_socket_info[socket].socket_cpu_mask = NULL;
+        else
+            cat_socket_info[socket].socket_cpu_mask =
+                                    per_cpu(cpu_core_mask, next);
+    }
+}
+
 static int cpu_callback(
     struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
@@ -284,6 +305,9 @@ static int cpu_callback(
     case CPU_STARTING:
         psr_cpu_init(cpu);
         break;
+    case CPU_DYING:
+        psr_cpu_fini(cpu);
+        break;
     }
 
     return NOTIFY_DONE;
-- 
1.9.1


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel