Re: [Qemu-devel] [PATCH v16 13/14] vfio-pci: pass the aer error to guest

[Chen Fan <chen.fan.fnst@cn.fujitsu.com>]

On 01/18/2016 06:45 PM, Marcel Apfelbaum wrote:
> On 01/12/2016 04:43 AM, Cao jin wrote:
>> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
>>
>> when the vfio device encounters an uncorrectable error in host,
>> the vfio_pci driver will signal the eventfd registered by this
>> vfio device, the results in the qemu eventfd handler getting
>
> Maybe "the results in" -> resulting in
>
>> invoked.
>>
>> this patch is to pass the error to guest and have the guest driver
>> recover from the error.
>
> Maybe "Pass the error to... and let the ... "
>
>>
>> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
>> ---
>>   hw/vfio/pci.c | 53 
>> +++++++++++++++++++++++++++++++++++++++++++++++------
>>   1 file changed, 47 insertions(+), 6 deletions(-)
>>
>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>> index da4815e..efa5e01 100644
>> --- a/hw/vfio/pci.c
>> +++ b/hw/vfio/pci.c
>> @@ -2553,18 +2553,59 @@ 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,
>> +    };
>>
>>       if (!event_notifier_test_and_clear(&vdev->err_notifier)) {
>>           return;
>>       }
>>
>>       /*
>> -     * 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.
>> +     * in case the real hardware configration has been changed,
>
> configration -> configuration
>
>
>> +     * here we should recheck the bus reset capability.
>> +     */
>> +    if ((vdev->features & VFIO_FEATURE_ENABLE_AER) &&
>> +        vfio_check_host_bus_reset(vdev)) {
>> +        goto stop;
>> +    }
>> +    /*
>> +     * we should read the error details from the real hardware
>> +     * configuration spaces, here we only need to do is signaling
>> +     * to guest an uncorrectable error has occurred.
>> +     */
>> +    if ((vdev->features & VFIO_FEATURE_ENABLE_AER) &&
>> +        dev->exp.aer_cap) {
>
> Why do we need dev->exp.aer_cap check here? In patch 7/14 we fail the 
> device init
> process if this happens, right?

the property FEATURE_ENABLE_AER can't represent the vfio device actually 
has the aer
capability. so here we should check it.

>
>> +        uint8_t *aer_cap = dev->config + dev->exp.aer_cap;
>> +        uint32_t uncor_status;
>> +        bool isfatal;
>> +
>> +        uncor_status = vfio_pci_read_config(dev,
>> +                           dev->exp.aer_cap + PCI_ERR_UNCOR_STATUS, 4);
>> +
>> +        /*
>> +         * if we receive the error signal but not this device, we can
>
> maybe "if the error is not emitted by this device..."

thank you for your careful review for my bad english description in the 
patchset,
I will update them in the next version.

Thanks,
Chen

>
>
> Thanks,
> Marcel
>
>> +         * just ignore it.
>> +         */
>> +        if (!(uncor_status & ~0UL)) {
>> +            return;
>> +        }
>> +
>> +        isfatal = uncor_status & pci_get_long(aer_cap + 
>> PCI_ERR_UNCOR_SEVER);
>> +
>> +        msg.severity = isfatal ? PCI_ERR_ROOT_CMD_FATAL_EN :
>> +                                 PCI_ERR_ROOT_CMD_NONFATAL_EN;
>> +
>> +        pcie_aer_msg(dev, &msg);
>> +        return;
>> +    }
>> +
>> +stop:
>> +    /*
>> +     * If the aer capability is not exposed to the guest. we just
>> +     * terminate the guest to contain the error.
>>        */
>>
>>       error_report("%s(%04x:%02x:%02x.%x) Unrecoverable error 
>> detected.  "
>>
>
>
>
> .
>