Merge tag 'x86_apic_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 APIC updates from Borislav Petkov:

 - Always do default APIC routing setup so that cpumasks are properly
   allocated and are present when later accessed ("nosmp" and x2APIC)

 - Clarify the bit overlap between an old APIC and a modern, integrated
   one

* tag 'x86_apic_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/apic: Do apic driver probe for "nosmp" use case
  x86/apic: Clarify i82489DX bit overlap in APIC_LVT0

1 files changed, 12 insertions, 4 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 3c8f2c797a98..9b87ec6acdec 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -320,6 +320,9 @@ int lapic_get_maxlvt(void)
 #define APIC_DIVISOR 16
 #define TSC_DIVISOR  8
 
+/* i82489DX specific */
+#define		I82489DX_BASE_DIVIDER		(((0x2) << 18))
+
 /*
  * This function sets up the local APIC timer, with a timeout of
  * 'clocks' APIC bus clock. During calibration we actually call
@@ -340,8 +343,14 @@ static void __setup_APIC_LVTT(unsigned int clocks, int oneshot, int irqen)
 	else if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
 		lvtt_value |= APIC_LVT_TIMER_TSCDEADLINE;
 
+	/*
+	 * The i82489DX APIC uses bit 18 and 19 for the base divider.  This
+	 * overlaps with bit 18 on integrated APICs, but is not documented
+	 * in the SDM. No problem though. i82489DX equipped systems do not
+	 * have TSC deadline timer.
+	 */
 	if (!lapic_is_integrated())
-		lvtt_value |= SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV);
+		lvtt_value |= I82489DX_BASE_DIVIDER;
 
 	if (!irqen)
 		lvtt_value |= APIC_LVT_MASKED;
@@ -1419,22 +1428,21 @@ void __init apic_intr_mode_init(void)
 		return;
 	case APIC_VIRTUAL_WIRE:
 		pr_info("APIC: Switch to virtual wire mode setup\n");
-		default_setup_apic_routing();
 		break;
 	case APIC_VIRTUAL_WIRE_NO_CONFIG:
 		pr_info("APIC: Switch to virtual wire mode setup with no configuration\n");
 		upmode = true;
-		default_setup_apic_routing();
 		break;
 	case APIC_SYMMETRIC_IO:
 		pr_info("APIC: Switch to symmetric I/O mode setup\n");
-		default_setup_apic_routing();
 		break;
 	case APIC_SYMMETRIC_IO_NO_ROUTING:
 		pr_info("APIC: Switch to symmetric I/O mode setup in no SMP routine\n");
 		break;
 	}
 
+	default_setup_apic_routing();
+
 	if (x86_platform.apic_post_init)
 		x86_platform.apic_post_init();