[PULL 18/28] vfio: add vfio_device_get_irq_info() helper

["Cédric Le Goater" <clg@redhat.com>]

From: John Levon <john.levon@nutanix.com>

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>
---
 include/hw/vfio/vfio-device.h |  3 +++
 hw/vfio/ap.c                  | 19 ++++++++++---------
 hw/vfio/ccw.c                 | 20 +++++++++++---------
 hw/vfio/device.c              | 15 +++++++++++++++
 hw/vfio/pci.c                 | 23 +++++++++++------------
 hw/vfio/platform.c            |  6 +++---
 6 files changed, 53 insertions(+), 33 deletions(-)

diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 8b1437ba6654d08f65740f42dc3a50775d7f5cc1..a7eaaa31e7e98a1ec73eefde0d935842ef9da401 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -147,6 +147,9 @@ int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
 int vfio_device_get_region_info_type(VFIODevice *vbasedev, uint32_t type,
                                      uint32_t subtype, struct vfio_region_info **info);
 bool vfio_device_has_region_cap(VFIODevice *vbasedev, int region, uint16_t cap_type);
+
+int vfio_device_get_irq_info(VFIODevice *vbasedev, int index,
+                                struct vfio_irq_info *info);
 #endif
 
 /* Returns 0 on success, or a negative errno. */
diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
index 1207c08d8d94dc6b9004725f8e266c2ec4d04105..785c0a019754a436c59357cf957c4dc6f81ba578 100644
--- a/hw/vfio/ap.c
+++ b/hw/vfio/ap.c
@@ -74,10 +74,10 @@ static bool vfio_ap_register_irq_notifier(VFIOAPDevice *vapdev,
                                           unsigned int irq, Error **errp)
 {
     int fd;
-    size_t argsz;
+    int ret;
     IOHandler *fd_read;
     EventNotifier *notifier;
-    g_autofree struct vfio_irq_info *irq_info = NULL;
+    struct vfio_irq_info irq_info;
     VFIODevice *vdev = &vapdev->vdev;
 
     switch (irq) {
@@ -96,14 +96,15 @@ static bool vfio_ap_register_irq_notifier(VFIOAPDevice *vapdev,
         return false;
     }
 
-    argsz = sizeof(*irq_info);
-    irq_info = g_malloc0(argsz);
-    irq_info->index = irq;
-    irq_info->argsz = argsz;
+    ret = vfio_device_get_irq_info(vdev, irq, &irq_info);
+
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "vfio: Error getting irq info");
+        return false;
+    }
 
-    if (ioctl(vdev->fd, VFIO_DEVICE_GET_IRQ_INFO,
-              irq_info) < 0 || irq_info->count < 1) {
-        error_setg_errno(errp, errno, "vfio: Error getting irq info");
+    if (irq_info.count < 1) {
+        error_setg(errp, "vfio: Error getting irq info, count=0");
         return false;
     }
 
diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
index fde0c3fbef3ca2204381c8ee6d07b502d2160e63..ab3fabf991c35abb6c40d925f526c2a2d8955aef 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -376,8 +376,8 @@ static bool vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
                                            Error **errp)
 {
     VFIODevice *vdev = &vcdev->vdev;
-    g_autofree struct vfio_irq_info *irq_info = NULL;
-    size_t argsz;
+    struct vfio_irq_info irq_info;
+    int ret;
     int fd;
     EventNotifier *notifier;
     IOHandler *fd_read;
@@ -406,13 +406,15 @@ static bool vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
         return false;
     }
 
-    argsz = sizeof(*irq_info);
-    irq_info = g_malloc0(argsz);
-    irq_info->index = irq;
-    irq_info->argsz = argsz;
-    if (ioctl(vdev->fd, VFIO_DEVICE_GET_IRQ_INFO,
-              irq_info) < 0 || irq_info->count < 1) {
-        error_setg_errno(errp, errno, "vfio: Error getting irq info");
+    ret = vfio_device_get_irq_info(vdev, irq, &irq_info);
+
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "vfio: Error getting irq info");
+        return false;
+    }
+
+    if (irq_info.count < 1) {
+        error_setg(errp, "vfio: Error getting irq info, count=0");
         return false;
     }
 
diff --git a/hw/vfio/device.c b/hw/vfio/device.c
index 9673b0717ead435e117d8084720fde4ba3a13dd8..5d837092cba2c35ad17d93dd5c3627d83defc818 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -185,6 +185,21 @@ bool vfio_device_irq_set_signaling(VFIODevice *vbasedev, int index, int subindex
     return false;
 }
 
+int vfio_device_get_irq_info(VFIODevice *vbasedev, int index,
+                             struct vfio_irq_info *info)
+{
+    int ret;
+
+    memset(info, 0, sizeof(*info));
+
+    info->argsz = sizeof(*info);
+    info->index = index;
+
+    ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_IRQ_INFO, info);
+
+    return ret < 0 ? -errno : ret;
+}
+
 int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
                                 struct vfio_region_info **info)
 {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index e1fab21b47adb4df9b011b3efb6d7c15c84bc8c2..5ccfc67aef6e1653dcf47c88d53265072c7a95c6 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;
     }
 
diff --git a/hw/vfio/platform.c b/hw/vfio/platform.c
index ffb3681607e2816ff0c07e2b5cfd255b46500b10..9a21f2e50a2945a6658b9be4fdec1bc1c98d0f20 100644
--- a/hw/vfio/platform.c
+++ b/hw/vfio/platform.c
@@ -474,10 +474,10 @@ static bool vfio_populate_device(VFIODevice *vbasedev, Error **errp)
     QSIMPLEQ_INIT(&vdev->pending_intp_queue);
 
     for (i = 0; i < vbasedev->num_irqs; i++) {
-        struct vfio_irq_info irq = { .argsz = sizeof(irq) };
+        struct vfio_irq_info irq;
+
+        ret = vfio_device_get_irq_info(vbasedev, i, &irq);
 
-        irq.index = i;
-        ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_IRQ_INFO, &irq);
         if (ret) {
             error_setg_errno(errp, -ret, "failed to get device irq info");
             goto irq_err;
-- 
2.49.0