[PATCH v4 3/4] x86/irq: Fall back to irq_chip_retrigger_hierarchy() in msi_set_affinity()

[Naman Jain]

msi_set_affinity() re-injects a pending interrupt on its new target by
looking at the outermost domain chip and invoking its irq_retrigger()
callback directly, without checking whether that callback is present.

Keep calling the outermost chip's irq_retrigger() when it is present,
but fall back to irq_chip_retrigger_hierarchy() otherwise, which walks
up the interrupt hierarchy until it finds a chip that implements
irq_retrigger().

Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Reviewed-by: Shradha Gupta <shradhagupta@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Signed-off-by: Naman Jain <namjain@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/kernel/apic/msi.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/apic/msi.c b/arch/x86/kernel/apic/msi.c
index 66bc5d3e79db3..66647d51c0473 100644
--- a/arch/x86/kernel/apic/msi.c
+++ b/arch/x86/kernel/apic/msi.c
@@ -136,8 +136,14 @@ msi_set_affinity(struct irq_data *irqd, const struct cpumask *mask, bool force)
 	 * underlying vector store. It's just checking the local APIC's
 	 * IRR.
 	 */
-	if (lapic_vector_set_in_irr(cfg->vector))
-		irq_data_get_irq_chip(irqd)->irq_retrigger(irqd);
+	if (lapic_vector_set_in_irr(cfg->vector)) {
+		struct irq_chip *chip = irq_data_get_irq_chip(irqd);
+
+		if (chip->irq_retrigger)
+			chip->irq_retrigger(irqd);
+		else
+			irq_chip_retrigger_hierarchy(irqd);
+	}
 
 	return ret;
 }
-- 
2.43.0