Re: [Qemu-devel] [PATCH v13 07/13] vfio: add aer support for vfio device

[Alex Williamson]

On Wed, 2015-11-11 at 18:34 +0800, Cao jin wrote:
> From: Chen Fan <address@hidden>
> 
> Calling pcie_aer_init to initilize aer related registers for
> vfio device, then reload physical related registers to expose
> device capability.
> 
> Signed-off-by: Chen Fan <address@hidden>
> ---


What if VFIO_FEATURE_ENABLE_AER is enabled for a device that doesn't
posses an AER capability or isn't attached to a PCIe bus?  It appears
that we silently ignore it, which would lead to unregistering a hotplug
notifier that was never registered in 09/13 and needing to test both
VFIO_FEATURE_ENABLE_AER and exp.aer_cap in 12/13 as well as the
inconsistency that we often only test for VFIO_FEATURE_ENABLE_AER when
really we expect that to imply that AER is setup and enabled for the
device.  It seems like we need to error either within
vfio_add_capabilities() or after calling it if VFIO_FEATURE_ENABLE_AER
is specified but not configured.  If a user expects AER to be enabled
for a device by specifying aer=on, we need to fail if that's not
possible.

>  hw/vfio/pci.c | 82 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  hw/vfio/pci.h |  3 +++
>  2 files changed, 82 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 4bc2b51..2d34edf 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1806,6 +1806,68 @@ static int vfio_add_std_cap(VFIOPCIDevice *vdev, 
> uint8_t pos)
...
> +
> +    pcie_cap_deverr_init(pdev);
> +    ret = pcie_aer_init(pdev, pos, size);
> +    if (ret) {
> +        return ret;
> +    }

This branch is unnecessary, we can simply:

return pcie_aer_init(pdev, pos, size);

if we get this far.  Thanks,

Alex