[RFC PATCH v2 6/7] util/vfio-helpers: Allow to set EventNotifier to particular IRQ

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

Let qemu_vfio_pci_init_irq() take an 'index' argument, so we can
set the EventNotifier to a specific IRQ.
Add a safety check. Since our helper is limited to one single IRQ
we are safe.

Our only user is the NVMe block driver, update it (also safe because
it only uses the first IRQ).

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/qemu/vfio-helpers.h |  2 +-
 block/nvme.c                |  2 +-
 util/vfio-helpers.c         | 11 +++++++++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/qemu/vfio-helpers.h b/include/qemu/vfio-helpers.h
index 728f40922b..5c2d8ee5b3 100644
--- a/include/qemu/vfio-helpers.h
+++ b/include/qemu/vfio-helpers.h
@@ -28,6 +28,6 @@ void *qemu_vfio_pci_map_bar(QEMUVFIOState *s, int index,
 void qemu_vfio_pci_unmap_bar(QEMUVFIOState *s, int index, void *bar,
                              uint64_t offset, uint64_t size);
 int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
-                           Error **errp);
+                           int irq_index, Error **errp);
 
 #endif
diff --git a/block/nvme.c b/block/nvme.c
index 21b0770c02..a5ef571492 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -785,7 +785,7 @@ static int nvme_init(BlockDriverState *bs, const char *device, int namespace,
         }
     }
 
-    ret = qemu_vfio_pci_init_irq(s->vfio, &s->irq_notifier, errp);
+    ret = qemu_vfio_pci_init_irq(s->vfio, &s->irq_notifier, INDEX_ADMIN, errp);
     if (ret) {
         goto out;
     }
diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index 5781e4f066..7a934d1a1b 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -180,13 +180,20 @@ void qemu_vfio_pci_unmap_bar(QEMUVFIOState *s, int index, void *bar,
  * Initialize device IRQ with @irq_type and and register an event notifier.
  */
 int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
-                           Error **errp)
+                           int irq_index, Error **errp)
 {
     int r;
     struct vfio_irq_set *irq_set;
     size_t irq_set_size;
     struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info) };
 
+    if (irq_index >= s->irq_count) {
+        error_setg(errp,
+                   "Illegal interrupt %d (device initialized for %zu in total)",
+                   irq_index, s->irq_count);
+        return -EINVAL;
+    }
+
     irq_info.index = s->irq_type;
     if (ioctl(s->device, VFIO_DEVICE_GET_IRQ_INFO, &irq_info)) {
         error_setg_errno(errp, errno, "Failed to get device interrupt info");
@@ -196,7 +203,7 @@ 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);
+    s->eventfd[irq_index] = event_notifier_get_fd(e);
 
     irq_set_size = sizeof(*irq_set) + s->irq_count * sizeof(int32_t);
     irq_set = g_malloc0(irq_set_size);
-- 
2.21.3