irqchip/gic-v3-its: Synchronise INV command targetting a VLPI using VSYNC

We have so far alwways invalidated VLPIs usinc an INV+SYNC
sequence, but that's pretty wrong for two reasons:

- SYNC only synchronises physical LPIs
- The collection ID that for the associated LPI doesn't match
  the redistributor the vPE is associated with

Instead, send an INV+VSYNC for forwarded LPIs, ensuring that
the ITS can properly synchronise the invalidation of VLPIs.

Fixes: 015ec0386a ("irqchip/gic-v3-its: Add VLPI configuration handling")
Reported-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191108165805.3071-9-maz@kernel.org

drivers/irqchip/irq-gic-v3-its.c

@@ -703,6 +703,24 @@ static struct its_vpe *its_build_vmovp_cmd(struct its_node *its,
 	return valid_vpe(its, desc->its_vmovp_cmd.vpe);
 }
 
+static struct its_vpe *its_build_vinv_cmd(struct its_node *its,
+					  struct its_cmd_block *cmd,
+					  struct its_cmd_desc *desc)
+{
+	struct its_vlpi_map *map;
+
+	map = dev_event_to_vlpi_map(desc->its_inv_cmd.dev,
+				    desc->its_inv_cmd.event_id);
+
+	its_encode_cmd(cmd, GITS_CMD_INV);
+	its_encode_devid(cmd, desc->its_inv_cmd.dev->device_id);
+	its_encode_event_id(cmd, desc->its_inv_cmd.event_id);
+
+	its_fixup_cmd(cmd);
+
+	return valid_vpe(its, map->vpe);
+}
+
 static u64 its_cmd_ptr_to_offset(struct its_node *its,
 				 struct its_cmd_block *ptr)
 {
@@ -1069,6 +1087,20 @@ static void its_send_vinvall(struct its_node *its, struct its_vpe *vpe)
 	its_send_single_vcommand(its, its_build_vinvall_cmd, &desc);
 }
 
+static void its_send_vinv(struct its_device *dev, u32 event_id)
+{
+	struct its_cmd_desc desc;
+
+	/*
+	 * There is no real VINV command. This is just a normal INV,
+	 * with a VSYNC instead of a SYNC.
+	 */
+	desc.its_inv_cmd.dev = dev;
+	desc.its_inv_cmd.event_id = event_id;
+
+	its_send_single_vcommand(dev->its, its_build_vinv_cmd, &desc);
+}
+
 /*
  * irqchip functions - assumes MSI, mostly.
  */
@@ -1143,8 +1175,10 @@ static void lpi_update_config(struct irq_data *d, u8 clr, u8 set)
 	lpi_write_config(d, clr, set);
 	if (gic_rdists->has_direct_lpi && !irqd_is_forwarded_to_vcpu(d))
 		direct_lpi_inv(d);
-	else
+	else if (!irqd_is_forwarded_to_vcpu(d))
 		its_send_inv(its_dev, its_get_event_id(d));
+	else
+		its_send_vinv(its_dev, its_get_event_id(d));
 }
 
 static void its_vlpi_set_doorbell(struct irq_data *d, bool enable)