1 files changed, 68 insertions, 32 deletions

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index 70a8f9e31a2d..be86fce1a84e 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -1,10 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright 2016,2017 IBM Corporation.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
  */
 
 #define pr_fmt(fmt) "xive: " fmt
@@ -139,7 +135,7 @@ static u32 xive_read_eq(struct xive_q *q, bool just_peek)
 static u32 xive_scan_interrupts(struct xive_cpu *xc, bool just_peek)
 {
 	u32 irq = 0;
-	u8 prio;
+	u8 prio = 0;
 
 	/* Find highest pending priority */
 	while (xc->pending_prio != 0) {
@@ -152,8 +148,19 @@ static u32 xive_scan_interrupts(struct xive_cpu *xc, bool just_peek)
 		irq = xive_read_eq(&xc->queue[prio], just_peek);
 
 		/* Found something ? That's it */
-		if (irq)
-			break;
+		if (irq) {
+			if (just_peek || irq_to_desc(irq))
+				break;
+			/*
+			 * We should never get here; if we do then we must
+			 * have failed to synchronize the interrupt properly
+			 * when shutting it down.
+			 */
+			pr_crit("xive: got interrupt %d without descriptor, dropping\n",
+				irq);
+			WARN_ON(1);
+			continue;
+		}
 
 		/* Clear pending bits */
 		xc->pending_prio &= ~(1 << prio);
@@ -311,6 +318,7 @@ static void xive_do_queue_eoi(struct xive_cpu *xc)
  */
 static void xive_do_source_eoi(u32 hw_irq, struct xive_irq_data *xd)
 {
+	xd->stale_p = false;
 	/* If the XIVE supports the new "store EOI facility, use it */
 	if (xd->flags & XIVE_IRQ_FLAG_STORE_EOI)
 		xive_esb_write(xd, XIVE_ESB_STORE_EOI, 0);
@@ -354,7 +362,7 @@ static void xive_do_source_eoi(u32 hw_irq, struct xive_irq_data *xd)
 	}
 }
 
-/* irq_chip eoi callback */
+/* irq_chip eoi callback, called with irq descriptor lock held */
 static void xive_irq_eoi(struct irq_data *d)
 {
 	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
@@ -370,6 +378,8 @@ static void xive_irq_eoi(struct irq_data *d)
 	if (!irqd_irq_disabled(d) && !irqd_is_forwarded_to_vcpu(d) &&
 	    !(xd->flags & XIVE_IRQ_NO_EOI))
 		xive_do_source_eoi(irqd_to_hwirq(d), xd);
+	else
+		xd->stale_p = true;
 
 	/*
 	 * Clear saved_p to indicate that it's no longer occupying
@@ -401,11 +411,16 @@ static void xive_do_source_set_mask(struct xive_irq_data *xd,
 	 */
 	if (mask) {
 		val = xive_esb_read(xd, XIVE_ESB_SET_PQ_01);
-		xd->saved_p = !!(val & XIVE_ESB_VAL_P);
-	} else if (xd->saved_p)
+		if (!xd->stale_p && !!(val & XIVE_ESB_VAL_P))
+			xd->saved_p = true;
+		xd->stale_p = false;
+	} else if (xd->saved_p) {
 		xive_esb_read(xd, XIVE_ESB_SET_PQ_10);
-	else
+		xd->saved_p = false;
+	} else {
 		xive_esb_read(xd, XIVE_ESB_SET_PQ_00);
+		xd->stale_p = false;
+	}
 }
 
 /*
@@ -483,7 +498,7 @@ static int xive_find_target_in_mask(const struct cpumask *mask,
 	 * Now go through the entire mask until we find a valid
 	 * target.
 	 */
-	for (;;) {
+	do {
 		/*
 		 * We re-check online as the fallback case passes us
 		 * an untested affinity mask
@@ -491,12 +506,11 @@ static int xive_find_target_in_mask(const struct cpumask *mask,
 		if (cpu_online(cpu) && xive_try_pick_target(cpu))
 			return cpu;
 		cpu = cpumask_next(cpu, mask);
-		if (cpu == first)
-			break;
 		/* Wrap around */
 		if (cpu >= nr_cpu_ids)
 			cpu = cpumask_first(mask);
-	}
+	} while (cpu != first);
+
 	return -1;
 }
 
@@ -546,6 +560,8 @@ static unsigned int xive_irq_startup(struct irq_data *d)
 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
 	int target, rc;
 
+	xd->saved_p = false;
+	xd->stale_p = false;
 	pr_devel("xive_irq_startup: irq %d [0x%x] data @%p\n",
 		 d->irq, hw_irq, d);
 
@@ -592,6 +608,7 @@ static unsigned int xive_irq_startup(struct irq_data *d)
 	return 0;
 }
 
+/* called with irq descriptor lock held */
 static void xive_irq_shutdown(struct irq_data *d)
 {
 	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
@@ -607,16 +624,6 @@ static void xive_irq_shutdown(struct irq_data *d)
 	xive_do_source_set_mask(xd, true);
 
 	/*
-	 * The above may have set saved_p. We clear it otherwise it
-	 * will prevent re-enabling later on. It is ok to forget the
-	 * fact that the interrupt might be in a queue because we are
-	 * accounting that already in xive_dec_target_count() and will
-	 * be re-routing it to a new queue with proper accounting when
-	 * it's started up again
-	 */
-	xd->saved_p = false;
-
-	/*
 	 * Mask the interrupt in HW in the IVT/EAS and set the number
 	 * to be the "bad" IRQ number
 	 */
@@ -802,6 +809,10 @@ static int xive_irq_retrigger(struct irq_data *d)
 	return 1;
 }
 
+/*
+ * Caller holds the irq descriptor lock, so this won't be called
+ * concurrently with xive_get_irqchip_state on the same interrupt.
+ */
 static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 {
 	struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
@@ -825,6 +836,10 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 
 		/* Set it to PQ=10 state to prevent further sends */
 		pq = xive_esb_read(xd, XIVE_ESB_SET_PQ_10);
+		if (!xd->stale_p) {
+			xd->saved_p = !!(pq & XIVE_ESB_VAL_P);
+			xd->stale_p = !xd->saved_p;
+		}
 
 		/* No target ? nothing to do */
 		if (xd->target == XIVE_INVALID_TARGET) {
@@ -832,7 +847,7 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 			 * An untargetted interrupt should have been
 			 * also masked at the source
 			 */
-			WARN_ON(pq & 2);
+			WARN_ON(xd->saved_p);
 
 			return 0;
 		}
@@ -852,9 +867,8 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 		 * This saved_p is cleared by the host EOI, when we know
 		 * for sure the queue slot is no longer in use.
 		 */
-		if (pq & 2) {
-			pq = xive_esb_read(xd, XIVE_ESB_SET_PQ_11);
-			xd->saved_p = true;
+		if (xd->saved_p) {
+			xive_esb_read(xd, XIVE_ESB_SET_PQ_11);
 
 			/*
 			 * Sync the XIVE source HW to ensure the interrupt
@@ -867,8 +881,7 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 			 */
 			if (xive_ops->sync_source)
 				xive_ops->sync_source(hw_irq);
-		} else
-			xd->saved_p = false;
+		}
 	} else {
 		irqd_clr_forwarded_to_vcpu(d);
 
@@ -919,6 +932,23 @@ static int xive_irq_set_vcpu_affinity(struct irq_data *d, void *state)
 	return 0;
 }
 
+/* Called with irq descriptor lock held. */
+static int xive_get_irqchip_state(struct irq_data *data,
+				  enum irqchip_irq_state which, bool *state)
+{
+	struct xive_irq_data *xd = irq_data_get_irq_handler_data(data);
+
+	switch (which) {
+	case IRQCHIP_STATE_ACTIVE:
+		*state = !xd->stale_p &&
+			 (xd->saved_p ||
+			  !!(xive_esb_read(xd, XIVE_ESB_GET) & XIVE_ESB_VAL_P));
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
 static struct irq_chip xive_irq_chip = {
 	.name = "XIVE-IRQ",
 	.irq_startup = xive_irq_startup,
@@ -930,6 +960,7 @@ static struct irq_chip xive_irq_chip = {
 	.irq_set_type = xive_irq_set_type,
 	.irq_retrigger = xive_irq_retrigger,
 	.irq_set_vcpu_affinity = xive_irq_set_vcpu_affinity,
+	.irq_get_irqchip_state = xive_get_irqchip_state,
 };
 
 bool is_xive_irq(struct irq_chip *chip)
@@ -1343,6 +1374,11 @@ static void xive_flush_cpu_queue(unsigned int cpu, struct xive_cpu *xc)
 		xd = irq_desc_get_handler_data(desc);
 
 		/*
+		 * Clear saved_p to indicate that it's no longer pending
+		 */
+		xd->saved_p = false;
+
+		/*
 		 * For LSIs, we EOI, this will cause a resend if it's
 		 * still asserted. Otherwise do an MSI retrigger.
 		 */