[PATCH v4 2/2] x86/ucode/AMD: late load the patch on every logical thread

[Sergey Dyasli]

Currently late ucode loading is performed only on the first core of CPU
siblings.  But according to the latest recommendation from AMD, late
ucode loading should happen on every logical thread/core.

To achieve that, consider every logical cpu as "primary" when running on
AMD cpus, i.e. skip cpu_sibling_mask checks.

Signed-off-by: Sergey Dyasli <sergey.dya...@citrix.com>
---
v4:
- new patch
---
 xen/arch/x86/cpu/microcode/core.c | 35 ++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/xen/arch/x86/cpu/microcode/core.c 
b/xen/arch/x86/cpu/microcode/core.c
index ba6e7b42c6..f720030761 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -398,10 +398,16 @@ static int cf_check microcode_nmi_callback(
          (!ucode_in_nmi && cpu == primary) )
         return 0;
 
-    if ( cpu == primary )
+    if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
+        /* load ucode on every logical thread/core */
         ret = primary_thread_work(nmi_patch);
     else
-        ret = secondary_nmi_work();
+    {
+        if ( cpu == primary )
+            ret = primary_thread_work(nmi_patch);
+        else
+            ret = secondary_nmi_work();
+    }
     this_cpu(loading_err) = ret;
 
     return 0;
@@ -540,7 +546,6 @@ static int control_thread_fn(const struct microcode_patch 
*patch)
 static int cf_check do_microcode_update(void *patch)
 {
     unsigned int cpu = smp_processor_id();
-    int ret;
 
     /*
      * The control thread set state to coordinate ucode loading. Primary
@@ -548,13 +553,18 @@ static int cf_check do_microcode_update(void *patch)
      * the completion of the ucode loading process.
      */
     if ( cpu == cpumask_first(&cpu_online_map) )
-        ret = control_thread_fn(patch);
-    else if ( cpu == cpumask_first(this_cpu(cpu_sibling_mask)) )
-        ret = primary_thread_fn(patch);
-    else
-        ret = secondary_thread_fn();
+        return control_thread_fn(patch);
 
-    return ret;
+    if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
+        /* load ucode on every logical thread/core */
+        return primary_thread_fn(patch);
+    else
+    {
+        if ( cpu == cpumask_first(this_cpu(cpu_sibling_mask)) )
+            return primary_thread_fn(patch);
+        else
+            return secondary_thread_fn();
+    }
 }
 
 struct ucode_buf {
@@ -642,8 +652,13 @@ static long cf_check microcode_update_helper(void *data)
     /* Calculate the number of online CPU core */
     nr_cores = 0;
     for_each_online_cpu(cpu)
-        if ( cpu == cpumask_first(per_cpu(cpu_sibling_mask, cpu)) )
+    {
+        if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
+            /* load ucode on every logical thread/core */
+            nr_cores++;
+        else if ( cpu == cpumask_first(per_cpu(cpu_sibling_mask, cpu)) )
             nr_cores++;
+    }
 
     printk(XENLOG_INFO "%u cores are to update their microcode\n", nr_cores);
 
-- 
2.31.1