linux-kernel - [PATCH] x86/apic: check FADT settings after enable x2apic

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Message-Id: <1358214636-4801-1-git-send-email-song-bo.wang@hp.com>
Date:	Tue, 15 Jan 2013 09:50:36 +0800
From:	Stoney Wang <song-bo.wang@...com>
To:	suresh.b.siddha@...el.com
Cc:	linbao.zhang@...com, greg.pearson@...com,
	linux-kernel@...r.kernel.org, Stoney Wang <song-bo.wang@...com>
Subject: [PATCH] x86/apic: check FADT settings after enable x2apic

OS will enable x2apic mode even BIOS default in xapic mode.

FADT settings check (commit ea0dcf903e7d76aa5d483d876215fedcfdfe140f)
should be applied after detect default mode and change the mode (enable_IR_x2apic called)

Signed-off-by: Stoney Wang <song-bo.wang@...com>
---
 arch/x86/kernel/apic/x2apic_phys.c |   25 ++++++++++++++++---------
 1 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index e03a1e1..76ea60d 100644
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -20,18 +20,22 @@ static int set_x2apic_phys_mode(char *arg)
 }
 early_param("x2apic_phys", set_x2apic_phys_mode);
 
-static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
+static int x2apic_fadt_phys(void)
 {
-	if (x2apic_phys)
-		return x2apic_enabled();
-	else if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) &&
-		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL) &&
-		x2apic_enabled()) {
+	if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) &&
+		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL)) {
 		printk(KERN_DEBUG "System requires x2apic physical mode\n");
 		return 1;
 	}
-	else
-		return 0;
+	return 0;
+}
+
+static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
+{
+	if (x2apic_enabled())
+		return x2apic_phys || x2apic_fadt_phys();
+
+	return 0;
 }
 
 static void
@@ -85,7 +89,10 @@ static int x2apic_phys_probe(void)
 	if (x2apic_mode && x2apic_phys)
 		return 1;
 
-	return apic == &apic_x2apic_phys;
+	if (apic == &apic_x2apic_phys)
+		return 1;
+
+	return x2apic_enabled() && x2apic_fadt_phys();
 }
 
 static struct apic apic_x2apic_phys = {
-- 
1.7.1

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