[PATCH 14/16] util/vfio-helpers: Introduce qemu_vfio_pci_msix_set_irq()

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

Introduce qemu_vfio_pci_msix_set_irq() to set the event
notifier of a specific MSIX IRQ. All other registered IRQs
are left unmodified.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/qemu/vfio-helpers.h |  2 ++
 util/vfio-helpers.c         | 35 +++++++++++++++++++++++++++++++++++
 util/trace-events           |  1 +
 3 files changed, 38 insertions(+)

diff --git a/include/qemu/vfio-helpers.h b/include/qemu/vfio-helpers.h
index 492072cba2f..4c06694e03a 100644
--- a/include/qemu/vfio-helpers.h
+++ b/include/qemu/vfio-helpers.h
@@ -33,5 +33,7 @@ int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
                            int irq_type, Error **errp);
 int qemu_vfio_pci_msix_init_irqs(QEMUVFIOState *s,
                                  unsigned *irq_count, Error **errp);
+int qemu_vfio_pci_msix_set_irq(QEMUVFIOState *s, unsigned irq_index,
+                               EventNotifier *notifier, Error **errp);
 
 #endif
diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index d88e2c7dc1f..18142e6be86 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -232,6 +232,41 @@ int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
     return 0;
 }
 
+/**
+ * Initialize a MSIX IRQ and register its event notifier.
+ * @irq_index: MSIX IRQ index
+ * @notifier: notifier for the MSIX IRQ
+ */
+int qemu_vfio_pci_msix_set_irq(QEMUVFIOState *s, unsigned irq_index,
+                               EventNotifier *notifier, Error **errp)
+{
+    int r;
+    int fd = event_notifier_get_fd(notifier);
+    size_t irq_set_size;
+    struct vfio_irq_set *irq_set;
+
+    trace_qemu_vfio_pci_msix_set_irq(irq_index, fd);
+    irq_set_size = sizeof(*irq_set) + sizeof(int32_t);
+    irq_set = g_malloc0(irq_set_size);
+    /* Get to a known IRQ state */
+    *irq_set = (struct vfio_irq_set) {
+        .argsz = irq_set_size,
+        .flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER,
+        .index = VFIO_PCI_MSIX_IRQ_INDEX,
+        .start = irq_index,
+        .count = 1,
+    };
+    ((int32_t *)&irq_set->data)[0] = fd;
+    r = ioctl(s->device, VFIO_DEVICE_SET_IRQS, irq_set);
+    g_free(irq_set);
+    if (r) {
+        error_setg_errno(errp, errno, "Failed to setup device interrupt #%u",
+                         irq_index);
+        return -errno;
+    }
+    return 0;
+}
+
 /**
  * Initialize device MSIX IRQs and register event notifiers.
  * @irq_count: pointer to number of MSIX IRQs to initialize
diff --git a/util/trace-events b/util/trace-events
index ec93578b125..3a56c542a94 100644
--- a/util/trace-events
+++ b/util/trace-events
@@ -88,6 +88,7 @@ qemu_vfio_dma_map(void *s, void *host, size_t size, bool temporary, uint64_t *io
 qemu_vfio_dma_mapped(void *s, void *host, uint64_t iova, size_t size) "s %p host %p <-> iova 0x%"PRIx64" size 0x%zx"
 qemu_vfio_dma_unmap(void *s, void *host) "s %p host %p"
 qemu_vfio_msix_info_irqs(uint32_t count, unsigned asked) "msix irqs %"PRIu32" (asked: %u)"
+qemu_vfio_pci_msix_set_irq(unsigned irq_index, int fd) "msix irq %u notifier_fd %d"
 qemu_vfio_iommu_iova_pgsizes(uint64_t iova_pgsizes) "iommu page size bitmask: 0x%08"PRIx64
 qemu_vfio_pci_read_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "read cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
 qemu_vfio_pci_write_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "write cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
-- 
2.26.2