[PATCH] x86: Fix verify_quirk_intel_irqbalance()

Fix verify_quirk_intel_irqbalance(). genapic checks should really
happen only on affected versions of the E7520/E7320/E7525 based platforms.

AK: This should akpm's Coyote SDV

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 29 insertions, 4 deletions

diff --git a/arch/i386/kernel/quirks.c b/arch/i386/kernel/quirks.c
index a01320a7b636..34874c398b44 100644
--- a/arch/i386/kernel/quirks.c
+++ b/arch/i386/kernel/quirks.c
@@ -10,13 +10,38 @@
 #if defined(CONFIG_X86_IO_APIC) && defined(CONFIG_SMP) && defined(CONFIG_PCI)
 static void __devinit verify_quirk_intel_irqbalance(struct pci_dev *dev)
 {
+        u8 config, rev;
+        u32 word;
+
+        /* BIOS may enable hardware IRQ balancing for
+         * E7520/E7320/E7525(revision ID 0x9 and below)
+         * based platforms.
+         * For those platforms, make sure that the genapic is set to 'flat'
+         */
+        pci_read_config_byte(dev, PCI_CLASS_REVISION, &rev);
+        if (rev > 0x9)
+                return;
+
+        /* enable access to config space*/
+        pci_read_config_byte(dev, 0xf4, &config);
+        pci_write_config_byte(dev, 0xf4, config|0x2);
+
+        /* read xTPR register */
+        raw_pci_ops->read(0, 0, 0x40, 0x4c, 2, &word);
+
+        if (!(word & (1 << 13))) {
 #ifdef CONFIG_X86_64
-        if (genapic !=  &apic_flat)
-                panic("APIC mode must be flat on this system\n");
+                if (genapic !=  &apic_flat)
+                        panic("APIC mode must be flat on this system\n");
 #elif defined(CONFIG_X86_GENERICARCH)
-        if (genapic != &apic_default)
-                panic("APIC mode must be default(flat) on this system. Use apic=default\n");
+                if (genapic != &apic_default)
+                        panic("APIC mode must be default(flat) on this system. Use apic=default\n");
 #endif
+        }
+
+        /* put back the original value for config space*/
+        if (!(config & 0x2))
+                pci_write_config_byte(dev, 0xf4, config);
 }
 
 void __init quirk_intel_irqbalance(void)