Re: [PATCH v2 05/15] vfio: consistently handle return value for helpers

[Cédric Le Goater]

On 4/30/25 21:39, John Levon wrote:

Various bits of code that call vfio device APIs should consistently use
the "return -errno" approach for passing errors back, rather than
presuming errno is (still) set correctly.

Signed-off-by: John Levon <john.le...@nutanix.com>

Reviewed-by: Cédric Le Goater <c...@redhat.com>

Thanks,

C.

---
  hw/vfio/pci.c | 33 ++++++++++++++++++++-------------
  1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 407cf43387..768c48d7ad 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -398,7 +398,7 @@ static int vfio_enable_msix_no_vec(VFIOPCIDevice *vdev)

ret = ioctl(vdev->vbasedev.fd, VFIO_DEVICE_SET_IRQS, irq_set); - return ret;

+    return ret < 0 ? -errno : ret;
  }

static int vfio_enable_vectors(VFIOPCIDevice *vdev, bool msix)

@@ -459,7 +459,7 @@ static int vfio_enable_vectors(VFIOPCIDevice *vdev, bool 
msix)

g_free(irq_set); - return ret;

+    return ret < 0 ? -errno : ret;
  }

static void vfio_add_kvm_msi_virq(VFIOPCIDevice *vdev, VFIOMSIVector *vector,

@@ -581,7 +581,8 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
              vfio_device_irq_disable(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX);
              ret = vfio_enable_vectors(vdev, true);
              if (ret) {
-                error_report("vfio: failed to enable vectors, %d", ret);
+                error_report("vfio: failed to enable vectors, %s",
+                             strerror(-ret));
              }
          } else {
              Error *err = NULL;
@@ -695,7 +696,8 @@ static void vfio_msix_enable(VFIOPCIDevice *vdev)
      if (vdev->nr_vectors) {
          ret = vfio_enable_vectors(vdev, true);
          if (ret) {
-            error_report("vfio: failed to enable vectors, %d", ret);
+            error_report("vfio: failed to enable vectors, %s",
+                         strerror(-ret));
          }
      } else {
          /*
@@ -712,7 +714,8 @@ static void vfio_msix_enable(VFIOPCIDevice *vdev)
           */
          ret = vfio_enable_msix_no_vec(vdev);
          if (ret) {
-            error_report("vfio: failed to enable MSI-X, %d", ret);
+            error_report("vfio: failed to enable MSI-X, %s",
+                         strerror(-ret));
          }
      }

@@ -765,7 +768,8 @@ retry:

      ret = vfio_enable_vectors(vdev, false);
      if (ret) {
          if (ret < 0) {
-            error_report("vfio: Error: Failed to setup MSI fds: %m");
+            error_report("vfio: Error: Failed to setup MSI fds: %s",
+                         strerror(-ret));
          } else {
              error_report("vfio: Error: Failed to enable %d "
                           "MSI vectors, retry with %d", vdev->nr_vectors, ret);
@@ -882,17 +886,21 @@ static void vfio_update_msi(VFIOPCIDevice *vdev)
  static void vfio_pci_load_rom(VFIOPCIDevice *vdev)
  {
      g_autofree struct vfio_region_info *reg_info = NULL;
+    VFIODevice *vbasedev = &vdev->vbasedev;
      uint64_t size;
      off_t off = 0;
      ssize_t bytes;
+    int ret;
+
+    ret = vfio_device_get_region_info(vbasedev, VFIO_PCI_ROM_REGION_INDEX,
+                                      &reg_info);

- if (vfio_device_get_region_info(&vdev->vbasedev,

-                                    VFIO_PCI_ROM_REGION_INDEX, &reg_info)) {
-        error_report("vfio: Error getting ROM info: %m");
+    if (ret != 0) {
+        error_report("vfio: Error getting ROM info: %s", strerror(-ret));
          return;
      }

- trace_vfio_pci_load_rom(vdev->vbasedev.name, (unsigned long)reg_info->size,

+    trace_vfio_pci_load_rom(vbasedev->name, (unsigned long)reg_info->size,
                              (unsigned long)reg_info->offset,
                              (unsigned long)reg_info->flags);

@@ -901,8 +909,7 @@ static void vfio_pci_load_rom(VFIOPCIDevice *vdev) if (!vdev->rom_size) {

          vdev->rom_read_failed = true;
-        error_report("vfio-pci: Cannot read device rom at "
-                    "%s", vdev->vbasedev.name);
+        error_report("vfio-pci: Cannot read device rom at %s", vbasedev->name);
          error_printf("Device option ROM contents are probably invalid "
                      "(check dmesg).\nSkip option ROM probe with rombar=0, "
                      "or load from file with romfile=\n");
@@ -913,7 +920,7 @@ static void vfio_pci_load_rom(VFIOPCIDevice *vdev)
      memset(vdev->rom, 0xff, size);

while (size) {

-        bytes = pread(vdev->vbasedev.fd, vdev->rom + off,
+        bytes = pread(vbasedev->fd, vdev->rom + off,
                        size, vdev->rom_offset + off);
          if (bytes == 0) {
              break;