Re: [Qemu-devel] [PATCH RFC v11 4/4] vfio: add 'aer' property to expose aercap

[Cao jin <caoj.fnst@cn.fujitsu.com>]

On 01/19/2017 06:36 AM, Alex Williamson wrote:
> On Sat, 31 Dec 2016 17:13:08 +0800
> Cao jin <caoj.fnst@cn.fujitsu.com> wrote:
> 
>> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
>>
>> Add 'aer' property, let user choose whether expose the aer capability
>> or not.
> 
> But that's not what it does, it only controls the behavior in response
> to non-fatal errors, the capability is exposed regardless.
> 

This commit log is legacy, and defaults to off is a result of the
configuration restriction & your previous discussion, right?

In current version, if 'aer' property is off, we just allocate the
config space via pcie_add_capability(), we don't init the AER
capability, the value is all 0s there, so does that still mean
"capability is exposed regardless"?

>> Should disable aer feature by default, because only non-fatal
>> error is supported now. 
> 
> Why does that mean it should be disabled by default?  What bad thing
> happens if we enable this opportunistically?
> 
>> 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 | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>> index 9861f72..fc9db66 100644
>> --- a/hw/vfio/pci.c
>> +++ b/hw/vfio/pci.c
>> @@ -3057,6 +3057,8 @@ static Property vfio_pci_dev_properties[] = {
>>      DEFINE_PROP_UINT32("x-pci-sub-device-id", VFIOPCIDevice,
>>                         sub_device_id, PCI_ANY_ID),
>>      DEFINE_PROP_UINT32("x-igd-gms", VFIOPCIDevice, igd_gms, 0),
>> +    DEFINE_PROP_BIT("aer", VFIOPCIDevice, features,
>> +                    VFIO_FEATURE_ENABLE_AER_BIT, false),
>>      /*
>>       * TODO - support passed fds... is this necessary?
>>       * DEFINE_PROP_STRING("vfiofd", VFIOPCIDevice, vfiofd_name),
> 
> 
> 
> .
> 

-- 
Sincerely,
Cao jin