vfio: add vfio_device_get_irq_info() helper

Add a helper similar to vfio_device_get_region_info() and use it
everywhere.

Replace a couple of needless allocations with stack variables.

As a side-effect, this fixes a minor error reporting issue in the call
from vfio_msix_early_setup().

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: John Levon <john.levon@nutanix.com>
Link: https://lore.kernel.org/qemu-devel/20250507152020.1254632-5-john.levon@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 11 insertions, 12 deletions

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index e1fab21b47..5ccfc67aef 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -1555,8 +1555,7 @@ static bool vfio_msix_early_setup(VFIOPCIDevice *vdev, Error **errp)
     uint16_t ctrl;
     uint32_t table, pba;
     int ret, fd = vdev->vbasedev.fd;
-    struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info),
-                                      .index = VFIO_PCI_MSIX_IRQ_INDEX };
+    struct vfio_irq_info irq_info;
     VFIOMSIXInfo *msix;
 
     pos = pci_find_capability(&vdev->pdev, PCI_CAP_ID_MSIX);
@@ -1593,7 +1592,8 @@ static bool vfio_msix_early_setup(VFIOPCIDevice *vdev, Error **errp)
     msix->pba_offset = pba & ~PCI_MSIX_FLAGS_BIRMASK;
     msix->entries = (ctrl & PCI_MSIX_FLAGS_QSIZE) + 1;
 
-    ret = ioctl(vdev->vbasedev.fd, VFIO_DEVICE_GET_IRQ_INFO, &irq_info);
+    ret = vfio_device_get_irq_info(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX,
+                                   &irq_info);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "failed to get MSI-X irq info");
         g_free(msix);
@@ -2736,7 +2736,7 @@ static bool vfio_populate_device(VFIOPCIDevice *vdev, Error **errp)
 {
     VFIODevice *vbasedev = &vdev->vbasedev;
     g_autofree struct vfio_region_info *reg_info = NULL;
-    struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info) };
+    struct vfio_irq_info irq_info;
     int i, ret = -1;
 
     /* Sanity check device */
@@ -2797,12 +2797,10 @@ static bool vfio_populate_device(VFIOPCIDevice *vdev, Error **errp)
         }
     }
 
-    irq_info.index = VFIO_PCI_ERR_IRQ_INDEX;
-
-    ret = ioctl(vdev->vbasedev.fd, VFIO_DEVICE_GET_IRQ_INFO, &irq_info);
+    ret = vfio_device_get_irq_info(vbasedev, VFIO_PCI_ERR_IRQ_INDEX, &irq_info);
     if (ret) {
         /* This can fail for an old kernel or legacy PCI dev */
-        trace_vfio_populate_device_get_irq_info_failure(strerror(errno));
+        trace_vfio_populate_device_get_irq_info_failure(strerror(-ret));
     } else if (irq_info.count == 1) {
         vdev->pci_aer = true;
     } else {
@@ -2911,17 +2909,18 @@ static void vfio_req_notifier_handler(void *opaque)
 
 static void vfio_register_req_notifier(VFIOPCIDevice *vdev)
 {
-    struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info),
-                                      .index = VFIO_PCI_REQ_IRQ_INDEX };
+    struct vfio_irq_info irq_info;
     Error *err = NULL;
     int32_t fd;
+    int ret;
 
     if (!(vdev->features & VFIO_FEATURE_ENABLE_REQ)) {
         return;
     }
 
-    if (ioctl(vdev->vbasedev.fd,
-              VFIO_DEVICE_GET_IRQ_INFO, &irq_info) < 0 || irq_info.count < 1) {
+    ret = vfio_device_get_irq_info(&vdev->vbasedev, VFIO_PCI_REQ_IRQ_INDEX,
+                                   &irq_info);
+    if (ret < 0 || irq_info.count < 1) {
         return;
     }