[PATCH v5 01/26] irqchip/gic-v3-its: Setup VLPI properties at map time

[Marc Zyngier]

So far, we require the hypervisor to update the VLPI properties
once the the VLPI mapping has been established. While this
makes it easy for the ITS driver, it creates a window where
an incoming interrupt can be delivered with an unknown set
of properties. Not very nice.

Instead, let's add a "properties" field to the mapping structure,
and use that to configure the VLPI before it actually gets mapped.

Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
 drivers/irqchip/irq-gic-v3-its.c   | 19 +++++++++++++++++--
 include/linux/irqchip/arm-gic-v4.h |  2 ++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 85f47ef4f1f7..2c4074c97454 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1006,9 +1006,15 @@ static void lpi_write_config(struct irq_data *d, u8 clr, u8 set)
 	if (irqd_is_forwarded_to_vcpu(d)) {
 		struct its_device *its_dev = irq_data_get_irq_chip_data(d);
 		u32 event = its_get_event_id(d);
+		struct its_vlpi_map *map;
 
 		prop_page = its_dev->event_map.vm->vprop_page;
-		hwirq = its_dev->event_map.vlpi_maps[event].vintid;
+		map = &its_dev->event_map.vlpi_maps[event];
+		hwirq = map->vintid;
+
+		/* Remember the updated property */
+		map->properties &= ~clr;
+		map->properties |= set | LPI_PROP_GROUP1;
 	} else {
 		prop_page = gic_rdists->prop_page;
 		hwirq = d->hwirq;
@@ -1018,6 +1024,7 @@ static void lpi_write_config(struct irq_data *d, u8 clr, u8 set)
 	*cfg &= ~clr;
 	*cfg |= set | LPI_PROP_GROUP1;
 
+
 	/*
 	 * Make the above write visible to the redistributors.
 	 * And yes, we're flushing exactly: One. Single. Byte.
@@ -1238,12 +1245,20 @@ static int its_vlpi_map(struct irq_data *d, struct its_cmd_info *info)
 		/* Ensure all the VPEs are mapped on this ITS */
 		its_map_vm(its_dev->its, info->map->vm);
 
+		/*
+		 * Flag the interrupt as forwarded so that we can
+		 * start poking the virtual property table.
+		 */
+		irqd_set_forwarded_to_vcpu(d);
+
+		/* Write out the property to the prop table */
+		lpi_write_config(d, 0xff, info->map->properties);
+
 		/* Drop the physical mapping */
 		its_send_discard(its_dev, event);
 
 		/* and install the virtual one */
 		its_send_vmapti(its_dev, event);
-		irqd_set_forwarded_to_vcpu(d);
 
 		/* Increment the number of VLPIs */
 		its_dev->event_map.nr_vlpis++;
diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h
index 43cde15f221b..447da8ca2156 100644
--- a/include/linux/irqchip/arm-gic-v4.h
+++ b/include/linux/irqchip/arm-gic-v4.h
@@ -71,12 +71,14 @@ struct its_vpe {
  * @vm:		Pointer to the GICv4 notion of a VM
  * @vpe:	Pointer to the GICv4 notion of a virtual CPU (VPE)
  * @vintid:	Virtual LPI number
+ * @properties:	Priority and enable bits (as written in the prop table)
  * @db_enabled:	Is the VPE doorbell to be generated?
  */
 struct its_vlpi_map {
 	struct its_vm		*vm;
 	struct its_vpe		*vpe;
 	u32			vintid;
+	u8			properties;
 	bool			db_enabled;
 };
 
-- 
2.11.0