Re: [Qemu-devel] [PATCH v3 3/8] pci: Convert msix_init() to Error and fix callers to check it

[Markus Armbruster <armbru@redhat.com>]

Cao jin <caoj.fnst@cn.fujitsu.com> writes:

> msix_init() reports errors with error_report(), which is wrong when
> it's used in realize().  The same issue was fixed for msi_init() in
> commit 1108b2f.
>
> For some devices(like e1000e, vmxnet3) who won't fail because of
> msix_init's failure, suppress the error report by passing NULL error object.
>
> Bonus: add comment for msix_init.
>
> CC: Jiri Pirko <jiri@resnulli.us>
> CC: Gerd Hoffmann <kraxel@redhat.com>
> CC: Dmitry Fleytman <dmitry@daynix.com>
> CC: Jason Wang <jasowang@redhat.com>
> CC: Michael S. Tsirkin <mst@redhat.com>
> CC: Hannes Reinecke <hare@suse.de>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> CC: Alex Williamson <alex.williamson@redhat.com>
> CC: Markus Armbruster <armbru@redhat.com>
> CC: Marcel Apfelbaum <marcel@redhat.com>
> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
[...]
> diff --git a/hw/pci/msix.c b/hw/pci/msix.c
> index 0cee631..d6b38fe 100644
> --- a/hw/pci/msix.c
> +++ b/hw/pci/msix.c
> @@ -21,6 +21,7 @@
>  #include "hw/pci/pci.h"
>  #include "hw/xen/xen.h"
>  #include "qemu/range.h"
> +#include "qapi/error.h"
>  
>  #define MSIX_CAP_LENGTH 12
>  
> @@ -238,11 +239,28 @@ static void msix_mask_all(struct PCIDevice *dev, unsigned nentries)
>      }
>  }
>  
> -/* Initialize the MSI-X structures */
> +/* Make PCI device @dev MSI-X capable
> + * @nentries is the max number of MSI-X vectors that the device support.
> + * @table_bar is the MemoryRegion that MSI-X table structure resides.
> + * @table_bar_nr is number of base address register corresponding to @table_bar.
> + * @table_offset indicates the offset that the MSI-X table structure starts with
> + * in @table_bar.
> + * @pba_bar is the MemoryRegion that the Pending Bit Array structure resides.
> + * @pba_bar_nr is number of base address register corresponding to @pba_bar.
> + * @pba_offset indicates the offset that the Pending Bit Array structure
> + * starts with in @pba_bar.
> + * Non-zero @cap_pos puts capability MSI-X at that offset in PCI config space.
> + *
> + * Return 0 on success; return -errno on error:

Previous version had:

  + * @errp is for returning errors.
  + *
  + * Return 0 on success; set @errp and return -errno on error.

Intentional change?  I like the old one better.

> + * -ENOTSUP means lacking msi support for a msi-capable platform.
> + * -EINVAL means capability overlap, happens when @cap_pos is non-zero,
> + * also means a programming error, except device assignment, which can check
> + * if a real HW is broken.*/
>  int msix_init(struct PCIDevice *dev, unsigned short nentries,
>                MemoryRegion *table_bar, uint8_t table_bar_nr,
>                unsigned table_offset, MemoryRegion *pba_bar,
> -              uint8_t pba_bar_nr, unsigned pba_offset, uint8_t cap_pos)
> +              uint8_t pba_bar_nr, unsigned pba_offset, uint8_t cap_pos,
> +              Error **errp)
>  {
>      int cap;
>      unsigned table_size, pba_size;
[...]
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 7bfa17c..87f4e11 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1349,6 +1349,7 @@ static int vfio_msix_early_setup(VFIOPCIDevice *vdev)
>  static int vfio_msix_setup(VFIOPCIDevice *vdev, int pos)
>  {
>      int ret;
> +    Error *err = NULL;
>  
>      vdev->msix->pending = g_malloc0(BITS_TO_LONGS(vdev->msix->entries) *
>                                      sizeof(unsigned long));
> @@ -1356,12 +1357,14 @@ static int vfio_msix_setup(VFIOPCIDevice *vdev, int pos)
>                      vdev->bars[vdev->msix->table_bar].region.mem,
>                      vdev->msix->table_bar, vdev->msix->table_offset,
>                      vdev->bars[vdev->msix->pba_bar].region.mem,
> -                    vdev->msix->pba_bar, vdev->msix->pba_offset, pos);
> +                    vdev->msix->pba_bar, vdev->msix->pba_offset, pos,
> +                    &err);
>      if (ret < 0) {
>          if (ret == -ENOTSUP) {
>              return 0;
>          }
> -        error_report("vfio: msix_init failed");
> +        error_prepend(&err, "vfio: msix_init failed: ");
> +        error_report_err(err);
>          return ret;
>      }
>  

Might conflict with Eric Auger's "Convert VFIO-PCI to realize" series,
but resolving that shouldn't be hard.

[...]

The conversion looks good to me now.