linux-kernel - [PATCH v2 09/11] irqchip/gic-v3-its: Synchronise INT/CLEAR commands targetting a VLPI using VSYNC

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Date:   Fri,  8 Nov 2019 16:58:03 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>, lorenzo.pieralisi@....com,
        Andrew.Murray@....com, yuzenghui@...wei.com,
        Heyi Guo <guoheyi@...wei.com>
Subject: [PATCH v2 09/11] irqchip/gic-v3-its: Synchronise INT/CLEAR commands targetting a VLPI using VSYNC

We have so far always injected/cleared VLPIs using either
INT+SYNC or CLEAR+SYNC sequences, 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 {INT,CLEAR}+VSYNC for forwarded LPIs, ensuring
that the ITS synchronises against the virtual pending table.

Reported-by: Zenghui Yu <yuzenghui@...wei.com>
Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 drivers/irqchip/irq-gic-v3-its.c | 79 ++++++++++++++++++++++++++++++--
 1 file changed, 75 insertions(+), 4 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 427496b7baf6..a83828e983ff 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -718,6 +718,42 @@ static struct its_vpe *its_build_vinv_cmd(struct its_node *its,
 	return valid_vpe(its, map->vpe);
 }
 
+static struct its_vpe *its_build_vint_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_int_cmd.dev,
+				    desc->its_int_cmd.event_id);
+
+	its_encode_cmd(cmd, GITS_CMD_INT);
+	its_encode_devid(cmd, desc->its_int_cmd.dev->device_id);
+	its_encode_event_id(cmd, desc->its_int_cmd.event_id);
+
+	its_fixup_cmd(cmd);
+
+	return valid_vpe(its, map->vpe);
+}
+
+static struct its_vpe *its_build_vclear_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_clear_cmd.dev,
+				    desc->its_clear_cmd.event_id);
+
+	its_encode_cmd(cmd, GITS_CMD_CLEAR);
+	its_encode_devid(cmd, desc->its_clear_cmd.dev->device_id);
+	its_encode_event_id(cmd, desc->its_clear_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)
 {
@@ -1098,6 +1134,34 @@ static void its_send_vinv(struct its_device *dev, u32 event_id)
 	its_send_single_vcommand(dev->its, its_build_vinv_cmd, &desc);
 }
 
+static void its_send_vint(struct its_device *dev, u32 event_id)
+{
+	struct its_cmd_desc desc;
+
+	/*
+	 * There is no real VINT command. This is just a normal INT,
+	 * with a VSYNC instead of a SYNC.
+	 */
+	desc.its_int_cmd.dev = dev;
+	desc.its_int_cmd.event_id = event_id;
+
+	its_send_single_vcommand(dev->its, its_build_vint_cmd, &desc);
+}
+
+static void its_send_vclear(struct its_device *dev, u32 event_id)
+{
+	struct its_cmd_desc desc;
+
+	/*
+	 * There is no real VCLEAR command. This is just a normal CLEAR,
+	 * with a VSYNC instead of a SYNC.
+	 */
+	desc.its_clear_cmd.dev = dev;
+	desc.its_clear_cmd.event_id = event_id;
+
+	its_send_single_vcommand(dev->its, its_build_vclear_cmd, &desc);
+}
+
 /*
  * irqchip functions - assumes MSI, mostly.
  */
@@ -1291,10 +1355,17 @@ static int its_irq_set_irqchip_state(struct irq_data *d,
 	if (which != IRQCHIP_STATE_PENDING)
 		return -EINVAL;
 
-	if (state)
-		its_send_int(its_dev, event);
-	else
-		its_send_clear(its_dev, event);
+	if (irqd_is_forwarded_to_vcpu(d)) {
+		if (state)
+			its_send_vint(its_dev, event);
+		else
+			its_send_vclear(its_dev, event);
+	} else {
+		if (state)
+			its_send_int(its_dev, event);
+		else
+			its_send_clear(its_dev, event);
+	}
 
 	return 0;
 }
-- 
2.20.1