Re: [Qemu-devel] [PATCH 2/3] vfio/pci: pass an error object to vfio_populate_device

[Markus Armbruster <armbru@redhat.com>]

Eric Auger <eric.auger@redhat.com> writes:

> Let's expand the usage of QEMU Error objects to vfio_populate_device.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
>  hw/vfio/pci.c | 45 ++++++++++++++++++++-------------------------
>  1 file changed, 20 insertions(+), 25 deletions(-)
>
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index ae1967c..f7768e9 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2197,7 +2197,7 @@ int vfio_populate_vga(VFIOPCIDevice *vdev)
>      return 0;
>  }
>  
> -static int vfio_populate_device(VFIOPCIDevice *vdev)
> +static void vfio_populate_device(VFIOPCIDevice *vdev, Error **errp)
>  {
>      VFIODevice *vbasedev = &vdev->vbasedev;
>      struct vfio_region_info *reg_info;
       struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info) };
       int i, ret = -1;
> @@ -2206,19 +2206,19 @@ static int vfio_populate_device(VFIOPCIDevice *vdev)
>  
>      /* Sanity check device */
>      if (!(vbasedev->flags & VFIO_DEVICE_FLAGS_PCI)) {
> -        error_report("vfio: Um, this isn't a PCI device");
> -        goto error;
> +        error_setg(errp, "this isn't a PCI device");
> +        return;

This is actually a bug fix :)

Before your series, vfio_populate_device() returns negative errno on
some errors, and -1 on others.  Its caller expects the former.

Please mention the fix in the commit message.  Fixing it in a separate
commit would also be fine, and possibly clearer.

>      }
>  
>      if (vbasedev->num_regions < VFIO_PCI_CONFIG_REGION_INDEX + 1) {
> -        error_report("vfio: unexpected number of io regions %u",
> -                     vbasedev->num_regions);
> -        goto error;
> +        error_setg(errp, "unexpected number of io regions %u",
> +                   vbasedev->num_regions);
> +        return;
>      }
>  
>      if (vbasedev->num_irqs < VFIO_PCI_MSIX_IRQ_INDEX + 1) {
> -        error_report("vfio: unexpected number of irqs %u", vbasedev->num_irqs);
> -        goto error;
> +        error_setg(errp, "unexpected number of irqs %u", vbasedev->num_irqs);
> +        return;
>      }
>  
>      for (i = VFIO_PCI_BAR0_REGION_INDEX; i < VFIO_PCI_ROM_REGION_INDEX; i++) {
> @@ -2229,8 +2229,8 @@ static int vfio_populate_device(VFIOPCIDevice *vdev)
>          g_free(name);
>  
>          if (ret) {
> -            error_report("vfio: Error getting region %d info: %m", i);
> -            goto error;
> +            error_setg_errno(errp, ret, "failed to get region %d info", i);
> +            return;
>          }
>  
>          QLIST_INIT(&vdev->bars[i].quirks);
> @@ -2239,8 +2239,8 @@ static int vfio_populate_device(VFIOPCIDevice *vdev)
>      ret = vfio_get_region_info(vbasedev,
>                                 VFIO_PCI_CONFIG_REGION_INDEX, &reg_info);
>      if (ret) {
> -        error_report("vfio: Error getting config info: %m");
> -        goto error;
> +        error_setg_errno(errp, ret, "failed to get config info");
> +        return;
>      }
>  
>      trace_vfio_populate_device_config(vdev->vbasedev.name,
> @@ -2259,9 +2259,9 @@ static int vfio_populate_device(VFIOPCIDevice *vdev)
>      if (vdev->features & VFIO_FEATURE_ENABLE_VGA) {
>          ret = vfio_populate_vga(vdev);
>          if (ret) {
> -            error_report(
> -                "vfio: Device does not support requested feature x-vga");
> -            goto error;
> +            error_setg_errno(errp, ret,
> +                "device does not support requested feature x-vga");
> +            return;
>          }
>      }
>  
> @@ -2271,17 +2271,11 @@ static int vfio_populate_device(VFIOPCIDevice *vdev)
>      if (ret) {
>          /* This can fail for an old kernel or legacy PCI dev */
>          trace_vfio_populate_device_get_irq_info_failure();
> -        ret = 0;
>      } else if (irq_info.count == 1) {
>          vdev->pci_aer = true;
>      } else {
> -        error_report("vfio: %s "
> -                     "Could not enable error recovery for the device",
> -                     vbasedev->name);
> +        error_setg_errno(errp, ret, "could not enable error recovery");

This isn't an error before this patch (ret stays zero).  Your patch
turns it into one.  Intentional?

>      }
> -
> -error:
> -    return ret;
>  }
>  
>  static void vfio_put_device(VFIOPCIDevice *vdev)
> @@ -2491,6 +2485,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>      VFIODevice *vbasedev_iter;
>      VFIOGroup *group;
>      char *tmp, group_path[PATH_MAX], *group_name;
> +    Error *err = NULL;
>      ssize_t len;
>      struct stat st;
>      int groupid;
> @@ -2554,9 +2549,9 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>          goto error;
>      }
>  
> -    ret = vfio_populate_device(vdev);
> -    if (ret) {
> -        error_setg_errno(errp, ret, "failed to populate the device");
> +    vfio_populate_device(vdev, &err);
> +    if (err) {
> +        error_propagate(errp, err);
>          goto error;
>      }