[PATCH]: x86: use acpi flags for apic mapping

[Prarit Bhargava]

ACPI FADT has entries to describe the apic mapping of a system.  Currently,
these are ignored in the apic code.

Introduce apic_is_acpi_clustered_box() and read the FADT to determine
if a box is clustered or not.

Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 1fa03e0..4518683 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -252,6 +252,14 @@ static inline int apic_is_clustered_box(void)
 }
 #endif
 
+enum apic_acpi_map_status {
+	APIC_ACPI_BOTH,
+	APIC_ACPI_CLUSTER,
+	APIC_ACPI_PHYSICAL,
+	APIC_ACPI_NONE
+};
+extern enum apic_acpi_map_status apic_is_acpi_clustered_box(void);
+
 extern u8 setup_APIC_eilvt_mce(u8 vector, u8 msg_type, u8 mask);
 extern u8 setup_APIC_eilvt_ibs(u8 vector, u8 msg_type, u8 mask);
 
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index e5a4a1e..6ca346a 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2189,6 +2189,30 @@ static const __cpuinitconst struct dmi_system_id multi_dmi_table[] = {
 	{}
 };
 
+#ifdef CONFIG_ACPI
+enum apic_acpi_map_status apic_is_acpi_clustered_box(void)
+{
+	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) {
+		if (acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL &&
+		    acpi_gbl_FADT.flags & ACPI_FADT_APIC_CLUSTER) {
+			/*
+			 * The rest of the code assumes physical flat
+			 * in this case.
+			 */
+			return APIC_ACPI_BOTH;
+		}
+
+		if (acpi_gbl_FADT.flags & ACPI_FADT_APIC_CLUSTER)
+			return APIC_ACPI_CLUSTER;
+
+		if (acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL)
+			return APIC_ACPI_PHYSICAL;
+	}
+
+	return APIC_ACPI_NONE;
+}
+#endif
+
 static void __cpuinit dmi_check_multi(void)
 {
 	if (multi_checked)
@@ -2208,6 +2232,20 @@ static void __cpuinit dmi_check_multi(void)
  */
 __cpuinit int apic_is_clustered_box(void)
 {
+#ifdef CONFIG_ACPI
+	switch (apic_is_acpi_clustered_box()) {
+		case APIC_ACPI_PHYSICAL:
+		case APIC_ACPI_BOTH: /* assume physical flat in this case */
+			return 0;
+			break;
+		case APIC_ACPI_CLUSTER:
+			return 1;
+			break;
+		default:
+			break;
+	}
+#endif
+
 	dmi_check_multi();
 	if (multi)
 		return 1;
diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
index 09d3b17..80e291a 100644
--- a/arch/x86/kernel/apic/apic_flat_64.c
+++ b/arch/x86/kernel/apic/apic_flat_64.c
@@ -231,14 +231,32 @@ static int physflat_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
 {
 #ifdef CONFIG_ACPI
 	/*
-	 * Quirk: some x86_64 machines can only use physical APIC mode
-	 * regardless of how many processors are present (x86_64 ES7000
-	 * is an example).
+	 * Some x86_64 machines can only use clustered or physical APIC
+	 * mode regardless of how many processors are present.
 	 */
-	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
-		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL)) {
-		printk(KERN_DEBUG "system APIC only can use physical flat");
-		return 1;
+	switch (apic_is_acpi_clustered_box()) {
+		case APIC_ACPI_BOTH:
+			printk(KERN_WARNING FW_BUG "ACPI has set apic mode to "
+			       "both clustered and physical flat.  Please "
+			       "contact your firmware vendor for an update.\n");
+			/*
+			 * In this case assume physical flat as only a very
+			 * limited number of systems use cluster
+			 */
+			printk(KERN_DEBUG "system APIC using physical flat\n");
+			return 1;
+			break;
+		case APIC_ACPI_CLUSTER:
+			printk(KERN_DEBUG "system APIC can only use cluster\n");
+			return 0;
+			break;
+		case APIC_ACPI_PHYSICAL:
+			printk(KERN_DEBUG "system APIC can only use physical"
+			       " flat\n");
+			return 1;
+			break;
+		default:
+			break;
 	}
 
 	if (!strncmp(oem_id, "IBM", 3) && !strncmp(oem_table_id, "EXA", 3)) {
--
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