Re: [Qemu-devel] [PATCH 11/12] vfio: register aer resume notification handler for aer resume

[Zhou Jie]

Hi, Alex

>> Do we even need a timer?  What if we simply spin?
>>
>> for (i = 0; i < 1000; i++) {
>>     if (vdev->pci_aer_resume_signaled) {
>>         break;
>>     }
>>     g_usleep(1000);
>> }
>>
>> if (i == 1000) {
>>     /* We failed */
>> } else {
>>     /* Proceed with reset */
>> }
>>
>> Does QEMU have enough concurrency to do this?  Thanks,On 2016/5/25
In my test, it can not work.
vfio_aer_resume_notifier_handler is invoked after vfio_pci_reset.
It is useless to wait in vfio_pci_reset.

Sincerely,
Zhou Jie

14:23, Zhou Jie wrote:
> Hi, Alex
>
> > > >   3. Stall any access to the device until resume is signaled.
> > >
> > > The code below doesn't actually do this, mmaps are disabled, but that
> > > just means any device access will use the slow path through QEMU.  That
> > > path is still fully enabled and so is config space access.
> > I will modify the code and find other way to
> > stall any access to the device.
>
> I find that to stall any access to the device,
> I need modify the following function.
> 1. vfio_region_read and vfio_region_write
>    For stalling any access to the device bar region.
> 2. vfio_vga_read and vfio_vga_write
>    For stalling any access to the vga device region.
> 3. vfio_pci_read_config and vfio_pci_write_config
>    For stalling any access to the device config space.
>
> What will happen if I don't stall any access to the device?
>
> Sincerely,
> Zhou Jie