x86/MCE/AMD: Carve out the MC4_MISC thresholding quirk

The MC4_MISC thresholding quirk needs to be applied during S5 -> S0 and
S3 -> S0 state transitions, which follow different code paths. Carve it
out into a separate function and call it mce_amd_feature_init() where
the two code paths of the state transitions converge.

[ bp: massage commit message and the carved out function. ]

Signed-off-by: Shirish S <[e-mail]>
Signed-off-by: Borislav Petkov <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Tony Luck <[e-mail]>
Cc: Vishal Verma <[e-mail]>
Cc: Yazen Ghannam <[e-mail]>
Cc: x86-ml <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

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

···
 	return offset;
 }
 
+/*
+ * Turn off MC4_MISC thresholding banks on all family 0x15 models since
+ * they're not supported there.
+ */
+void disable_err_thresholding(struct cpuinfo_x86 *c)
+{
+	int i;
+	u64 hwcr;
+	bool need_toggle;
+	u32 msrs[] = {
+		0x00000413, /* MC4_MISC0 */
+		0xc0000408, /* MC4_MISC1 */
+	};
+
+	if (c->x86 != 0x15)
+		return;
+
+	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));
+
+	/* Clear CntP bit safely */
+	for (i = 0; i < ARRAY_SIZE(msrs); i++)
+		msr_clear_bit(msrs[i], 62);
+
+	/* restore old settings */
+	if (need_toggle)
+		wrmsrl(MSR_K7_HWCR, hwcr);
+}
+
 /* cpu init entry point, called from mce.c with preempt off */
 void mce_amd_feature_init(struct cpuinfo_x86 *c)
 {
 	u32 low = 0, high = 0, address = 0;
 	unsigned int bank, block, cpu = smp_processor_id();
 	int offset = -1;
+
+	disable_err_thresholding(c);
 
 	for (bank = 0; bank < mca_cfg.banks; ++bank) {
 		if (mce_flags.smca)

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

···
 		if (c->x86 == 0x15 && c->x86_model <= 0xf)
 			mce_flags.overflow_recov = 1;
 
-		/*
-		 * Turn off MC4_MISC thresholding banks on all models since
-		 * they're not supported there.
-		 */
-		if (c->x86 == 0x15) {
-			int i;
-			u64 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));
-
-			/* Clear CntP bit safely */
-			for (i = 0; i < ARRAY_SIZE(msrs); i++)
-				msr_clear_bit(msrs[i], 62);
-
-			/* restore old settings */
-			if (need_toggle)
-				wrmsrl(MSR_K7_HWCR, hwcr);
-		}
 	}
 
 	if (c->x86_vendor == X86_VENDOR_INTEL) {