x86: microcode_amd: fix wrong handling of equivalent CPU id

Impact: fix bug resulting in non-loaded AMD microcode

mc_header->processor_rev_id is a 2 byte value. Similar is true for
equiv_cpu in an equiv_cpu_entry -- only 2 bytes are of interest.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 17 deletions

diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
index 5f8e5d75a254..b5bc81470bcf 100644
--- a/arch/x86/kernel/microcode_amd.c
+++ b/arch/x86/kernel/microcode_amd.c
@@ -62,7 +62,7 @@ struct microcode_header_amd {
         unsigned int  mc_patch_data_checksum;
         unsigned int  nb_dev_id;
         unsigned int  sb_dev_id;
-        unsigned char processor_rev_id[2];
+        u16 processor_rev_id;
         unsigned char nb_rev_id;
         unsigned char sb_rev_id;
         unsigned char bios_api_rev;
@@ -125,7 +125,7 @@ static int get_matching_microcode(int cpu, void *mc, int rev)
 
         while (equiv_cpu_table[i].installed_cpu != 0) {
                 if (current_cpu_id == equiv_cpu_table[i].installed_cpu) {
-                        equiv_cpu_id = equiv_cpu_table[i].equiv_cpu;
+                        equiv_cpu_id = equiv_cpu_table[i].equiv_cpu & 0xffff;
                         break;
                 }
                 i++;
@@ -137,21 +137,10 @@ static int get_matching_microcode(int cpu, void *mc, int rev)
                 return 0;
         }
 
-        if ((mc_header->processor_rev_id[0]) != (equiv_cpu_id & 0xff)) {
-                printk(KERN_ERR
-                        "microcode: CPU%d patch does not match "
-                        "(patch is %x, cpu extended is %x) \n",
-                        cpu, mc_header->processor_rev_id[0],
-                        (equiv_cpu_id & 0xff));
-                return 0;
-        }
-
-        if ((mc_header->processor_rev_id[1]) != ((equiv_cpu_id >> 16) & 0xff)) {
-                printk(KERN_ERR "microcode: CPU%d patch does not match "
-                        "(patch is %x, cpu base id is %x) \n",
-                        cpu, mc_header->processor_rev_id[1],
-                        ((equiv_cpu_id >> 16) & 0xff));
-
+        if (mc_header->processor_rev_id != equiv_cpu_id) {
+                printk(KERN_ERR "microcode: CPU%d patch does not match "
+                       "(processor_rev_id: %x, eqiv_cpu_id: %x)\n",
+                       cpu, mc_header->processor_rev_id, equiv_cpu_id);
                 return 0;
         }