Re: [PATCH] vfio/pci: Propagate errors in vfio_pci_load_rom() using Error API

[Cédric Le Goater]

Hello Mario,

On 6/11/26 11:43, Mario Casquero wrote:

Updates vfio_pci_load_rom() to use Error API for error propagation
instead of error_report(), improving error handling consistency.

Signed-off-by: Mario Casquero <mcasq...@redhat.com>
---
  hw/vfio/pci.c | 19 +++++++++----------
  1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 9df04fa2d7..11876fd5b4 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -1027,7 +1027,7 @@ static void vfio_update_msi(VFIOPCIDevice *vdev)
      }
  }

-static bool vfio_pci_load_rom(VFIOPCIDevice *vdev)

+static bool vfio_pci_load_rom(VFIOPCIDevice *vdev, Error **errp)
  {
      VFIODevice *vbasedev = &vdev->vbasedev;
      struct vfio_region_info *reg_info = NULL;
@@ -1040,7 +1040,7 @@ static bool vfio_pci_load_rom(VFIOPCIDevice *vdev)
                                        &reg_info);

if (ret != 0) {

-        error_report("vfio: Error getting ROM info: %s", strerror(-ret));
+        error_setg_errno(errp, -ret, "vfio: Error getting ROM info");
          return false;
      }

@@ -1052,10 +1052,10 @@ static bool vfio_pci_load_rom(VFIOPCIDevice *vdev)

      vdev->rom_offset = reg_info->offset;

if (!vdev->rom_size) {

-        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");
+        error_setg(errp, "vfio-pci: Cannot read device rom at %s. "
+                   "Device option ROM contents are probably invalid "
+                   "(check dmesg). Skip option ROM probe with rombar=0, "
+                   "or load from file with romfile=", vbasedev->name);

Here I would add :

    error_setg(errp, "vfio-pci: Cannot read device rom at %s", vbasedev->name);

and keep the error_printf() as it is.

The error_setg() propagates the error and error_printf() emits
the "hint" whether the caller handles or not the error.

          return false;
      }

@@ -1076,9 +1076,8 @@ static bool vfio_pci_load_rom(VFIOPCIDevice *vdev)

              if (bytes == -EINTR || bytes == -EAGAIN) {
                  continue;
              }
-            error_report("vfio: Error reading device ROM: %s",
-                         strreaderror(bytes));
-
+            error_setg(errp, "vfio: Error reading device ROM: %s",
+                       strreaderror(bytes));

May be instead :

    error_setg_errno(errp, -bytes, "vfio: Error reading device ROM");

and since vdev->rom_size and vdev->rom_offset are left dirty :

    g_free(vdev->rom);
    vdev->rom = NULL;
    vdev->rom_size = 0;
    vdev->rom_offset = 0;
    return false;

              break;
          }
      }
@@ -1147,7 +1146,7 @@ static uint64_t vfio_rom_read(void *opaque, hwaddr addr, 
unsigned size)

/* Load the ROM lazily when the guest tries to read it */

      if (unlikely(!vdev->rom && !vdev->rom_read_failed)) {
-        vdev->rom_read_failed = !vfio_pci_load_rom(vdev);
+        vdev->rom_read_failed = !vfio_pci_load_rom(vdev, NULL);

The NULL 'errp' parameter will silently discard the error of
vfio_pci_load_rom(). All error_setg() / error_setg_errno() calls
become no-ops.

This would be better :

    Error *local_err = NULL;

    vdev->rom_read_failed = !vfio_pci_load_rom(vdev, &local_err);
    if (vdev->rom_read_failed) {
        error_report_err(local_err);
    }

Thanks,

C.

      }

memcpy(&val, vdev->rom + addr,