[RFC PATCH v2 5/7] util/vfio-helpers: Support multiple eventfd

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

When using multiple IRQs, we'll assign an eventfd to each IRQ.
Be ready by holding an array of eventfd file descriptors in the
instance state, so when we assign new IRQs we will still use the
previous eventfds for the already assigned IRQs.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 util/vfio-helpers.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index b81d4c70c2..5781e4f066 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -45,6 +45,7 @@ struct QEMUVFIOState {
 
     int irq_type; /* vfio index */
     size_t irq_count; /* vfio subindex (vector) */
+    int32_t *eventfd;
 
     /* These fields are protected by BQL */
     int container;
@@ -195,6 +196,7 @@ int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
         error_setg(errp, "Device interrupt doesn't support eventfd");
         return -EINVAL;
     }
+    s->eventfd[0] = event_notifier_get_fd(e);
 
     irq_set_size = sizeof(*irq_set) + s->irq_count * sizeof(int32_t);
     irq_set = g_malloc0(irq_set_size);
@@ -207,8 +209,8 @@ int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
         .start = 0,
         .count = s->irq_count,
     };
+    memcpy(&irq_set->data, &s->eventfd, s->irq_count * sizeof(int32_t));
 
-    *(int32_t *)&irq_set->data = event_notifier_get_fd(e);
     r = ioctl(s->device, VFIO_DEVICE_SET_IRQS, irq_set);
     g_free(irq_set);
     if (r) {
@@ -343,6 +345,10 @@ static int qemu_vfio_init_pci(QEMUVFIOState *s, const char *device,
     }
     s->irq_type = irq_type;
     s->irq_count = irq_count;
+    s->eventfd = g_new(int32_t, irq_count);
+    for (i = 0; i < irq_count; i++) {
+        s->eventfd[i] = -1;
+    }
 
     if (device_info.num_regions < VFIO_PCI_CONFIG_REGION_INDEX) {
         error_setg(errp, "Invalid device regions");
@@ -379,6 +385,7 @@ static int qemu_vfio_init_pci(QEMUVFIOState *s, const char *device,
     }
     return 0;
 fail:
+    g_free(s->eventfd);
     close(s->group);
 fail_container:
     close(s->container);
@@ -730,6 +737,7 @@ void qemu_vfio_close(QEMUVFIOState *s)
     }
     ram_block_notifier_remove(&s->ram_notifier);
     qemu_vfio_reset(s);
+    g_free(s->eventfd);
     close(s->device);
     close(s->group);
     close(s->container);
-- 
2.21.3