[PATCH v2 1/5] irqchip/gic-v5: Skip deactivate for forwarded PPI interrupts

[Sascha Bischoff <Sascha.Bischoff@arm.com>]

If a PPI interrupt is forwarded to a guest, skip the deactivate and
only EOI. Rely on the guest deactivating both the virtual and physical
interrupts (due to ICH_LRx_EL2.HW being set) later on as part of
handling the injected interrupt. This mimics the behaviour seen on
native GICv3.

This is part of adding support for the GICv3 compatibility mode on a
GICv5 host.

Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>

Co-authored-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
---
 drivers/irqchip/irq-gic-v5.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-gic-v5.c
index 7a11521eeeca..6b42c4af5c79 100644
--- a/drivers/irqchip/irq-gic-v5.c
+++ b/drivers/irqchip/irq-gic-v5.c
@@ -213,6 +213,12 @@ static void gicv5_hwirq_eoi(u32 hwirq_id, u8 hwirq_type)
 
 static void gicv5_ppi_irq_eoi(struct irq_data *d)
 {
+	/* Skip deactivate for forwarded PPI interrupts */
+	if (irqd_is_forwarded_to_vcpu(d)) {
+		gic_insn(0, CDEOI);
+		return;
+	}
+
 	gicv5_hwirq_eoi(d->hwirq, GICV5_HWIRQ_TYPE_PPI);
 }
 
@@ -494,6 +500,16 @@ static bool gicv5_ppi_irq_is_level(irq_hw_number_t hwirq)
 	return !!(read_ppi_sysreg_s(hwirq, PPI_HM) & bit);
 }
 
+static int gicv5_ppi_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu)
+{
+	if (vcpu)
+		irqd_set_forwarded_to_vcpu(d);
+	else
+		irqd_clr_forwarded_to_vcpu(d);
+
+	return 0;
+}
+
 static const struct irq_chip gicv5_ppi_irq_chip = {
 	.name			= "GICv5-PPI",
 	.irq_mask		= gicv5_ppi_irq_mask,
@@ -501,6 +517,7 @@ static const struct irq_chip gicv5_ppi_irq_chip = {
 	.irq_eoi		= gicv5_ppi_irq_eoi,
 	.irq_get_irqchip_state	= gicv5_ppi_irq_get_irqchip_state,
 	.irq_set_irqchip_state	= gicv5_ppi_irq_set_irqchip_state,
+	.irq_set_vcpu_affinity	= gicv5_ppi_irq_set_vcpu_affinity,
 	.flags			= IRQCHIP_SKIP_SET_WAKE	  |
 				  IRQCHIP_MASK_ON_SUSPEND,
 };
-- 
2.34.1