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Re: [Xen-devel] [PATCH v8 23/27] ARM: vITS: handle INV command



Hi Andre,

On 12/04/17 01:44, Andre Przywara wrote:
The INV command instructs the ITS to update the configuration data for
a given LPI by re-reading its entry from the property table.
We don't need to care so much about the priority value, but enabling
or disabling an LPI has some effect: We remove or push virtual LPIs
to their VCPUs, also check the virtual pending bit if an LPI gets enabled.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/arch/arm/vgic-v3-its.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
index 09cb3af..f2789c5 100644
--- a/xen/arch/arm/vgic-v3-its.c
+++ b/xen/arch/arm/vgic-v3-its.c
@@ -418,6 +418,68 @@ static int update_lpi_property(struct domain *d, uint32_t 
vlpi,
     return 0;
 }

+/*
+ * Checks whether an LPI that got enabled or disabled needs to change
+ * something in the VGIC (added or removed from the LR or queues).
+ * Must be called with the VCPU VGIC lock held.
+ */
+static void update_lpi_vgic_status(struct vcpu *v, struct pending_irq *p,
+                                   uint32_t vlpi)

p->irq should be equal to vlpi. No?

+{
+    ASSERT(spin_is_locked(&v->arch.vgic.lock));

The locking is likely to wrong here too (see patch #2). For instance with a MOVI then INV on interrupt enabled.

+
+    if ( test_bit(GIC_IRQ_GUEST_ENABLED, &p->status) )
+    {
+        if ( !list_empty(&p->inflight) &&
+             !test_bit(GIC_IRQ_GUEST_VISIBLE, &p->status) )
+            gic_raise_guest_irq(v, vlpi, p->lpi_priority);
+    }
+    else
+    {
+        clear_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
+        list_del_init(&p->lr_queue);
+    }
+}
+
+static int its_handle_inv(struct virt_its *its, uint64_t *cmdptr)
+{
+    struct domain *d = its->d;
+    uint32_t devid = its_cmd_get_deviceid(cmdptr);
+    uint32_t eventid = its_cmd_get_id(cmdptr);
+    struct pending_irq *p;
+    unsigned long flags;
+    struct vcpu *vcpu;
+    uint32_t vlpi;
+    int ret = -1;
+
+    /* Translate the event into a vCPU/vLPI pair. */
+    if ( !read_itte(its, devid, eventid, &vcpu, &vlpi) )
+        return -1;
+
+    if ( vlpi == INVALID_LPI )
+        return -1;
+
+    spin_lock_irqsave(&vcpu->arch.vgic.lock, flags);
+
+    p = d->arch.vgic.handler->lpi_to_pending(d, vlpi);
+    if ( !p )
+        goto out_unlock;

As said on v5, this could be simpler and use the pending_irqs in the device. That would be an improvement though. So a would be good.

+
+    /* Read the property table and update our cached status. */
+    if ( update_lpi_property(d, vlpi, p) )
+        goto out_unlock;
+
+    /* Check whether the LPI needs to go on a VCPU. */
+    update_lpi_vgic_status(vcpu, p, vlpi);
+
+    ret = 0;
+
+out_unlock:
+    spin_unlock_irqrestore(&vcpu->arch.vgic.lock, flags);
+
+    return ret;
+}
+
 static int its_handle_mapc(struct virt_its *its, uint64_t *cmdptr)
 {
     uint32_t collid = its_cmd_get_collection(cmdptr);
@@ -757,6 +819,9 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
virt_its *its)
         case GITS_CMD_INT:
             ret = its_handle_int(its, command);
             break;
+        case GITS_CMD_INV:
+            ret = its_handle_inv(its, command);
+            break;
         case GITS_CMD_MAPC:
             ret = its_handle_mapc(its, command);
             break;


Cheers,

--
Julien Grall

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