1 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index f7e98a2c0d12..1b7d1656a042 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -631,6 +631,20 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
                 }
         }
 
+        /*
+         * The way access filter has a performance penalty on some workloads.
+         * Disable it on the affected CPUs.
+         */
+        if ((c->x86 == 0x15) &&
+            (c->x86_model >= 0x02) && (c->x86_model < 0x20)) {
+                u64 val;
+
+                if (!rdmsrl_safe(0xc0011021, &val) && !(val & 0x1E)) {
+                        val |= 0x1E;
+                        wrmsrl_safe(0xc0011021, val);
+                }
+        }
+
         cpu_detect_cache_sizes(c);
 
         /* Multi core CPU? */