irqchip/gic-v3-its: Add VLPI configuration handling

When a VLPI is reconfigured (enabled, disabled, change in priority),
the full configuration byte must be written, and the caches invalidated.

Also, when using the irq_mask/irq_unmask methods, it is necessary
to disable the doorbell for that particular interrupt (by mapping it
to 1023) on top of clearing the Enable bit.

Reviewed-by: Thomas Gleixner <[e-mail]>
Reviewed-by: Eric Auger <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>

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

···
 	return d->hwirq - its_dev->event_map.lpi_base;
 }
 
-static void lpi_update_config(struct irq_data *d, u8 clr, u8 set)
+static void lpi_write_config(struct irq_data *d, u8 clr, u8 set)
 {
-	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
-	irq_hw_number_t hwirq = d->hwirq;
+	irq_hw_number_t hwirq;
 	struct page *prop_page;
 	u8 *cfg;
 
-	prop_page = gic_rdists->prop_page;
+	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);
+
+		prop_page = its_dev->event_map.vm->vprop_page;
+		hwirq = its_dev->event_map.vlpi_maps[event].vintid;
+	} else {
+		prop_page = gic_rdists->prop_page;
+		hwirq = d->hwirq;
+	}
 
 	cfg = page_address(prop_page) + hwirq - 8192;
 	*cfg &= ~clr;
-	*cfg |= set;
+	*cfg |= set | LPI_PROP_GROUP1;
 
 	/*
 	 * Make the above write visible to the redistributors.
···
 		gic_flush_dcache_to_poc(cfg, sizeof(*cfg));
 	else
 		dsb(ishst);
+}
+
+static void lpi_update_config(struct irq_data *d, u8 clr, u8 set)
+{
+	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
+
+	lpi_write_config(d, clr, set);
 	its_send_inv(its_dev, its_get_event_id(d));
+}
+
+static void its_vlpi_set_doorbell(struct irq_data *d, bool enable)
+{
+	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
+	u32 event = its_get_event_id(d);
+
+	if (its_dev->event_map.vlpi_maps[event].db_enabled == enable)
+		return;
+
+	its_dev->event_map.vlpi_maps[event].db_enabled = enable;
+
+	/*
+	 * More fun with the architecture:
+	 *
+	 * Ideally, we'd issue a VMAPTI to set the doorbell to its LPI
+	 * value or to 1023, depending on the enable bit. But that
+	 * would be issueing a mapping for an /existing/ DevID+EventID
+	 * pair, which is UNPREDICTABLE. Instead, let's issue a VMOVI
+	 * to the /same/ vPE, using this opportunity to adjust the
+	 * doorbell. Mouahahahaha. We loves it, Precious.
+	 */
+	its_send_vmovi(its_dev, event);
 }
 
 static void its_mask_irq(struct irq_data *d)
 {
+	if (irqd_is_forwarded_to_vcpu(d))
+		its_vlpi_set_doorbell(d, false);
+
 	lpi_update_config(d, LPI_PROP_ENABLED, 0);
 }
 
 static void its_unmask_irq(struct irq_data *d)
 {
+	if (irqd_is_forwarded_to_vcpu(d))
+		its_vlpi_set_doorbell(d, true);
+
 	lpi_update_config(d, 0, LPI_PROP_ENABLED);
 }
 
···
 	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
 	struct its_collection *target_col;
 	u32 id = its_get_event_id(d);
+
+	/* A forwarded interrupt should use irq_set_vcpu_affinity */
+	if (irqd_is_forwarded_to_vcpu(d))
+		return -EINVAL;
 
        /* lpi cannot be routed to a redistributor that is on a foreign node */
 	if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) {
···
 	return ret;
 }
 
+static int its_vlpi_prop_update(struct irq_data *d, struct its_cmd_info *info)
+{
+	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
+
+	if (!its_dev->event_map.vm || !irqd_is_forwarded_to_vcpu(d))
+		return -EINVAL;
+
+	if (info->cmd_type == PROP_UPDATE_AND_INV_VLPI)
+		lpi_update_config(d, 0xff, info->config);
+	else
+		lpi_write_config(d, 0xff, info->config);
+	its_vlpi_set_doorbell(d, !!(info->config & LPI_PROP_ENABLED));
+
+	return 0;
+}
+
 static int its_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu_info)
 {
 	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
···
 
 	case PROP_UPDATE_VLPI:
 	case PROP_UPDATE_AND_INV_VLPI:
+		return its_vlpi_prop_update(d, info);
 
 	default:
 		return -EINVAL;