x86, MCE, AMD: Disable error thresholding bank 4 on some models

Turn off MC4_MISC thresholding banks on models which have them but that
particular processor implementation does not supply applicable error
sources to be counted.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

arch/x86/kernel/cpu/mcheck/mce.c

@@ -1423,6 +1423,43 @@ static int __cpuinit __mcheck_cpu_apply_quirks(struct cpuinfo_x86 *c)
 		 */
 		 if (c->x86 == 6 && banks > 0)
 			mce_banks[0].ctl = 0;
+
+		 /*
+		  * Turn off MC4_MISC thresholding banks on those models since
+		  * they're not supported there.
+		  */
+		 if (c->x86 == 0x15 &&
+		     (c->x86_model >= 0x10 && c->x86_model <= 0x1f)) {
+			 int i;
+			 u64 val, hwcr;
+			 bool need_toggle;
+			 u32 msrs[] = {
+				0x00000413, /* MC4_MISC0 */
+				0xc0000408, /* MC4_MISC1 */
+			 };
+
+			 rdmsrl(MSR_K7_HWCR, hwcr);
+
+			 /* McStatusWrEn has to be set */
+			 need_toggle = !(hwcr & BIT(18));
+
+			 if (need_toggle)
+				 wrmsrl(MSR_K7_HWCR, hwcr | BIT(18));
+
+			 for (i = 0; i < ARRAY_SIZE(msrs); i++) {
+				 rdmsrl(msrs[i], val);
+
+				 /* CntP bit set? */
+				 if (val & BIT(62)) {
+					 val &= ~BIT(62);
+					 wrmsrl(msrs[i], val);
+				 }
+			 }
+
+			 /* restore old settings */
+			 if (need_toggle)
+				 wrmsrl(MSR_K7_HWCR, hwcr);
+		 }
 	}
 
 	if (c->x86_vendor == X86_VENDOR_INTEL) {