x86/mce: Update bootlog description to reflect behavior on AMD

The bootlog option is only disabled by default on AMD Fam10h and older
systems.

Update bootlog description to say this. Change the family value to hex
to avoid confusion.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20170613162835.30750-9-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Documentation/x86/x86_64/boot-options.txt

@@ -36,7 +36,8 @@ Machine check
 		to broadcast MCEs.
    mce=bootlog
 		Enable logging of machine checks left over from booting.
-		Disabled by default on AMD because some BIOS leave bogus ones.
+		Disabled by default on AMD Fam10h and older because some BIOS
+		leave bogus ones.
 		If your BIOS doesn't do that it's a good idea to enable though
 		to make sure you log even machine check events that result
 		in a reboot. On Intel systems it is enabled by default.

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

@@ -1550,7 +1550,7 @@ static int __mcheck_cpu_apply_quirks(struct cpuinfo_x86 *c)
 			 */
 			clear_bit(10, (unsigned long *)&mce_banks[4].ctl);
 		}
-		if (c->x86 < 17 && cfg->bootlog < 0) {
+		if (c->x86 < 0x11 && cfg->bootlog < 0) {
 			/*
 			 * Lots of broken BIOS around that don't clear them
 			 * by default and leave crap in there. Don't log:
@@ -1832,7 +1832,8 @@ void mce_disable_bank(int bank)
  * mce=TOLERANCELEVEL[,monarchtimeout] (number, see above)
  *	monarchtimeout is how long to wait for other CPUs on machine
  *	check, or 0 to not wait
- * mce=bootlog Log MCEs from before booting. Disabled by default on AMD.
+ * mce=bootlog Log MCEs from before booting. Disabled by default on AMD Fam10h
+	and older.
  * mce=nobootlog Don't log MCEs from before booting.
  * mce=bios_cmci_threshold Don't program the CMCI threshold
  * mce=recovery force enable memcpy_mcsafe()