[Xen-devel] [PATCH 17/28] ARM: vITS: handle CLEAR command

[Andre Przywara <andre.przywara@xxxxxxx>]

This introduces the ITS command handler for the CLEAR command, which
clears the pending state of an LPI.
This removes a not-yet injected, but already queued IRQ from a VCPU.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/arch/arm/vgic-v3-its.c | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
index 982c51d..48eb924 100644
--- a/xen/arch/arm/vgic-v3-its.c
+++ b/xen/arch/arm/vgic-v3-its.c
@@ -129,8 +129,8 @@ static void put_devid_evid(struct virt_its *its, struct 
vits_itte *itte)
  * protect the ITTs with their less-than-page-size granularity.
  * Takes and drops the its_lock.
  */
-bool read_itte(struct virt_its *its, uint32_t devid, uint32_t evid,
-               struct vcpu **vcpu, uint32_t *vlpi)
+static bool read_itte(struct virt_its *its, uint32_t devid, uint32_t evid,
+                      struct vcpu **vcpu, uint32_t *vlpi)
 {
     struct vits_itte *itte;
     int collid;
@@ -214,6 +214,34 @@ static uint64_t its_cmd_mask_field(uint64_t *its_cmd,
 #define its_cmd_get_target_addr(cmd)    its_cmd_mask_field(cmd, 2, 16, 32)
 #define its_cmd_get_validbit(cmd)       its_cmd_mask_field(cmd, 2, 63,  1)
 
+static int its_handle_clear(struct virt_its *its, uint64_t *cmdptr)
+{
+    uint32_t devid = its_cmd_get_deviceid(cmdptr);
+    uint32_t eventid = its_cmd_get_id(cmdptr);
+    struct pending_irq *pirq;
+    struct vcpu *vcpu;
+    uint32_t vlpi;
+
+    if ( !read_itte(its, devid, eventid, &vcpu, &vlpi) )
+        return -1;
+
+    /* Remove a pending, but not yet injected guest IRQ. */
+    pirq = lpi_to_pending(vcpu, vlpi, false);
+    if ( pirq )
+    {
+        clear_bit(GIC_IRQ_GUEST_QUEUED, &pirq->status);
+        gic_remove_from_queues(vcpu, vlpi);
+
+        /* Mark this pending IRQ struct as availabe again. */
+        if ( !test_bit(GIC_IRQ_GUEST_VISIBLE, &pirq->status) )
+            pirq->irq = 0;
+    }
+
+    clear_bit(vlpi - LPI_OFFSET, vcpu->arch.vgic.pendtable);
+
+    return 0;
+}
+
 #define ITS_CMD_BUFFER_SIZE(baser)      ((((baser) & 0xff) + 1) << 12)
 
 static int vgic_its_handle_cmds(struct domain *d, struct virt_its *its,
@@ -234,6 +262,9 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
virt_its *its,
         cmdptr = its->cmdbuf + (its->creadr / sizeof(*its->cmdbuf));
         switch (its_cmd_get_command(cmdptr))
         {
+        case GITS_CMD_CLEAR:
+            its_handle_clear(its, cmdptr);
+            break;
         case GITS_CMD_SYNC:
             /* We handle ITS commands synchronously, so we ignore SYNC. */
            break;
-- 
2.9.0


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