From: Jeremy Fitzhardinge <jeremy@goop.org>
Date: Wed, 22 Jul 2009 16:59:35 +0000 (-0700)
Subject: x86, amd: Don't probe for extended APIC ID if APICs are disabled
X-Git-Tag: v2.6.31-rc5~87^2~1
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=2cb078603abb612e3bcd428fb8122c3d39e08832;p=linux-2.6-block.git

x86, amd: Don't probe for extended APIC ID if APICs are disabled

If we've logically disabled apics, don't probe the PCI space for the
AMD extended APIC ID.

[ Impact: prevent boot crash under Xen. ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Reported-by: Bastian Blank <bastian@waldi.eu.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 28e5f5956042..e2485b03f1cf 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -356,7 +356,7 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c)
 #endif
 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PCI)
 	/* check CPU config space for extended APIC ID */
-	if (c->x86 >= 0xf) {
+	if (cpu_has_apic && c->x86 >= 0xf) {
 		unsigned int val;
 		val = read_pci_config(0, 24, 0, 0x68);
 		if ((val & ((1 << 17) | (1 << 18))) == ((1 << 17) | (1 << 18)))