separate lapic_enable from lapic_setup

This initializes the lapic without
turning on the IOAPIC interrupts during SMP init.

Message-ID: <20240207050158.1640853-2-damien@zamaudio.com>

4 files changed, 31 insertions, 5 deletions

diff --git a/i386/i386/apic.c b/i386/i386/apic.c
index 700fafd3..feb49c85 100644
--- a/i386/i386/apic.c
+++ b/i386/i386/apic.c
@@ -309,6 +309,18 @@ void apic_send_ipi(unsigned dest_shorthand, unsigned deliv_mode, unsigned dest_m
 void
 lapic_enable(void)
 {
+    lapic->spurious_vector.r |= LAPIC_ENABLE;
+}
+
+void
+lapic_disable(void)
+{
+    lapic->spurious_vector.r &= ~LAPIC_ENABLE;
+}
+
+void
+lapic_setup(void)
+{
     unsigned long flags;
     int apic_id;
     volatile uint32_t dummy;
@@ -338,8 +350,7 @@ lapic_enable(void)
     /* Enable LAPIC to send or recieve IPI/SIPIs */
     dummy = lapic->spurious_vector.r;
     lapic->spurious_vector.r = IOAPIC_SPURIOUS_BASE
-			     | LAPIC_ENABLE_DIRECTED_EOI
-			     | LAPIC_ENABLE;
+			     | LAPIC_ENABLE_DIRECTED_EOI;
 
     lapic->error_status.r = 0;
 
diff --git a/i386/i386/apic.h b/i386/i386/apic.h
index e1d49895..29387d9d 100644
--- a/i386/i386/apic.h
+++ b/i386/i386/apic.h
@@ -244,6 +244,8 @@ int apic_get_total_gsis(void);
 void picdisable(void);
 void lapic_eoi(void);
 void ioapic_irq_eoi(int pin);
+void lapic_setup(void);
+void lapic_disable(void);
 void lapic_enable(void);
 void lapic_enable_timer(void);
 void calibrate_lapic_timer(void);
diff --git a/i386/i386/mp_desc.c b/i386/i386/mp_desc.c
index 76b4a79c..a5f6b8f6 100644
--- a/i386/i386/mp_desc.c
+++ b/i386/i386/mp_desc.c
@@ -270,6 +270,7 @@ cpu_setup(int cpu)
     machine_slot[cpu].cpu_type = machine_slot[0].cpu_type;
 
     init_fpu();
+    lapic_setup();
     lapic_enable();
     cpu_launch_first_thread(THREAD_NULL);
 }
@@ -313,13 +314,21 @@ start_other_cpus(void)
 	memcpy((void*) phystokv(apboot_addr), (void*) &apboot,
 	       (uint32_t)&apbootend - (uint32_t)&apboot);
 
-#ifndef APIC
-	lapic_enable(); /* Enable lapic only once */
-#endif
 	unsigned cpu;
 
 	splhigh();
 
+	/* Disable IOAPIC interrupts (IPIs not affected).
+	 * Clearing this flag is similar to masking all
+	 * IOAPIC interrupts individually.
+	 *
+	 * This is done to prevent IOAPIC interrupts from
+	 * interfering with SMP startup. splhigh() may be enough for BSP,
+	 * but I'm not sure.  We cannot control the lapic
+	 * on APs because we don't have execution on them yet.
+	 */
+	lapic_disable();
+
 	bspdone = 0;
 	for (cpu = 1; cpu < ncpus; cpu++) {
 		machine_slot[cpu].running = FALSE;
@@ -336,5 +345,8 @@ start_other_cpus(void)
 		__sync_synchronize();
 	}
 	printf("BSP: Completed SMP init\n");
+
+	/* Re-enable IOAPIC interrupts as per setup */
+	lapic_enable();
 }
 #endif	/* NCPUS > 1 */
diff --git a/i386/i386at/ioapic.c b/i386/i386at/ioapic.c
index 270362c3..2553a2c9 100644
--- a/i386/i386at/ioapic.c
+++ b/i386/i386at/ioapic.c
@@ -458,5 +458,6 @@ ioapic_configure(void)
     }
 
     /* Start the IO APIC receiving interrupts */
+    lapic_setup();
     lapic_enable();
 }