Re: [Qemu-devel] [PATCH RFC v11 3/4] vfio-pci: pass the aer error to guest

["Michael S. Tsirkin" <mst@redhat.com>]

On Sat, Dec 31, 2016 at 05:13:07PM +0800, Cao jin wrote:
> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> 
> When physical device has uncorrectable error hanppened, the vfio_pci
> driver will signal the uncorrectable error status register value to
> corresponding QEMU's vfio-pci device via the eventfd registered by this
> device, then, the vfio-pci's error eventfd handler will be invoked in
> event loop.
> 
> Construct and pass the aer message to root port, root port will trigger an
> interrupt to signal guest, then, the guest driver will do the recovery.
> 
> Note: Now only support non-fatal error's recovery, fatal error will
> still result in vm stop.
> 
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> ---
>  hw/vfio/pci.c | 50 ++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 42 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 76a8ac3..9861f72 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2470,21 +2470,55 @@ static void vfio_put_device(VFIOPCIDevice *vdev)
>  static void vfio_err_notifier_handler(void *opaque)
>  {
>      VFIOPCIDevice *vdev = opaque;
> +    PCIDevice *dev = &vdev->pdev;
> +    PCIEAERMsg msg = {
> +        .severity = 0,
> +        .source_id = (pci_bus_num(dev->bus) << 8) | dev->devfn,
> +    };
> +    int len;
> +    uint64_t uncor_status;
> +
> +    /* Read uncorrectable error status from driver */
> +    len = read(vdev->err_notifier.rfd, &uncor_status, sizeof(uncor_status));
> +    if (len != sizeof(uncor_status)) {
> +        error_report("vfio-pci: uncor error status reading returns"
> +                     " invalid number of bytes: %d", len);
> +        return; //Or goto stop?

I would definitely suggest this to make sure we don't regress.

> +    }
> +
> +    if (!(vdev->features & VFIO_FEATURE_ENABLE_AER)) {
> +        goto stop;
> +    }
> +
> +    /* Populate the aer msg and send it to root port */
> +    if (dev->exp.aer_cap) {
> +        uint8_t *aer_cap = dev->config + dev->exp.aer_cap;
> +        bool isfatal = uncor_status &
> +                       pci_get_long(aer_cap + PCI_ERR_UNCOR_SEVER);
> +
> +	if (isfatal) {
> +	    goto stop;
> +	}
> +
> +        msg.severity = isfatal ? PCI_ERR_ROOT_CMD_FATAL_EN :
> +                                 PCI_ERR_ROOT_CMD_NONFATAL_EN;
>  
> -    if (!event_notifier_test_and_clear(&vdev->err_notifier)) {
> +        error_report("vfio-pci device %d sending AER to root port. uncor"
> +                     " status = 0x%"PRIx64, dev->devfn, uncor_status);
> +        pcie_aer_msg(dev, &msg);
>          return;
>      }
>  
> +stop:
>      /*
> -     * TBD. Retrieve the error details and decide what action
> -     * needs to be taken. One of the actions could be to pass
> -     * the error to the guest and have the guest driver recover
> -     * from the error. This requires that PCIe capabilities be
> -     * exposed to the guest. For now, we just terminate the
> -     * guest to contain the error.
> +     * Terminate the guest in case of
> +     * 1. AER capability is not exposed to guest.
> +     * 2. AER capability is exposed, but error is fatal, only non-fatal
> +     * error is handled now.
>       */
>  
> -    error_report("%s(%s) Unrecoverable error detected. Please collect any data possible and then kill the guest", __func__, vdev->vbasedev.name);
> +    error_report("%s(%s) fatal error detected. Please collect any data"
> +            " possible and then kill the guest", __func__, vdev->vbasedev.name);
>  
>      vm_stop(RUN_STATE_INTERNAL_ERROR);
>  }
> -- 
> 1.8.3.1
> 
>