EDAC, amd64: Don't force-enable ECC checking on newer systems

It's not recommended for the OS to try and force-enable ECC checking.
This is considered a firmware task since it includes memory training,
etc, so don't change ECC settings on Fam17h or newer systems and inform
the user.

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
Cc: Aravind Gopalakrishnan <aravindksg.lkml@gmail.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1479850816-1595-1-git-send-email-Yazen.Ghannam@amd.com
[ Put the "forcing" message in an else branch. ]
Signed-off-by: Borislav Petkov <bp@suse.de>

drivers/edac/amd64_edac.c

@@ -2629,7 +2629,6 @@ static void restore_ecc_error_reporting(struct ecc_settings *s, u16 nid,
 {
 	u32 value, mask = 0x3;		/* UECC/CECC enable */
 
-
 	if (!s->nbctl_valid)
 		return;
 
@@ -2895,7 +2894,11 @@ static int probe_one_instance(unsigned int nid)
 		if (!ecc_enable_override)
 			goto err_enable;
 
-		amd64_warn("Forcing ECC on!\n");
+		if (boot_cpu_data.x86 >= 0x17) {
+			amd64_warn("Forcing ECC on is not recommended on newer systems. Please enable ECC in BIOS.");
+			goto err_enable;
+		} else
+			amd64_warn("Forcing ECC on!\n");
 
 		if (!enable_ecc_error_reporting(s, nid, F3))
 			goto err_enable;
@@ -2904,7 +2907,9 @@ static int probe_one_instance(unsigned int nid)
 	ret = init_one_instance(nid);
 	if (ret < 0) {
 		amd64_err("Error probing instance: %d\n", nid);
-		restore_ecc_error_reporting(s, nid, F3);
+
+		if (boot_cpu_data.x86 < 0x17)
+			restore_ecc_error_reporting(s, nid, F3);
 	}
 
 	return ret;