linux-kernel - [PATCH] x86: fix compute high_width with phys-addr is 44bit and more

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Date:	Wed, 06 May 2009 21:36:16 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	Li Zefan <lizf@...fujitsu.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Zhaolei <zhaolei@...fujitsu.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: fix compute high_width with phys-addr is 44bit and more


found one system that cpu address line is 44bits, mtrr printout is not right.

[    0.000000] MTRR variable ranges enabled:
[    0.000000]   0 base 0   00000000 mask FF0 00000000 write-back
[    0.000000]   1 base 10  00000000 mask FFF 80000000 write-back
[    0.000000]   2 base 0   80000000 mask FFF 80000000 uncachable
[    0.000000]   3 base 0   7F800000 mask FFF FF800000 uncachable

Li Zefan and Frederic pointed out the high_width could be -4 some how.

it turns out when phys_addr is 44bit, size_or_mask will be ffffffff,00000000
so ffs(size_or_mask) will be 0.

try to check low 32 bit, to get correct high_width.

Signed-off-by: Yinghai Lu <yinghai@...ne.org>
Cc: Li Zefan <lizf@...fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>

---
 arch/x86/kernel/cpu/mtrr/generic.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-2.6/arch/x86/kernel/cpu/mtrr/generic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/mtrr/generic.c
+++ linux-2.6/arch/x86/kernel/cpu/mtrr/generic.c
@@ -275,7 +275,11 @@ static void __init print_mtrr_state(void
 	}
 	printk(KERN_DEBUG "MTRR variable ranges %sabled:\n",
 	       mtrr_state.enabled & 2 ? "en" : "dis");
-	high_width = ((size_or_mask ? ffs(size_or_mask) - 1 : 32) - (32 - PAGE_SHIFT) + 3) / 4;
+	if (size_or_mask & 0xffffffffUL)
+		high_width = ffs(size_or_mask & 0xffffffffUL) - 1;
+	else
+		high_width = ffs(size_or_mask>>32) + 32 - 1;
+	high_width = (high_width - (32 - PAGE_SHIFT) + 3) / 4;
 	for (i = 0; i < num_var_ranges; ++i) {
 		if (mtrr_state.var_ranges[i].mask_lo & (1 << 11))
 			printk(KERN_DEBUG "  %u base %0*X%05X000 mask %0*X%05X000 %s\n",
--
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