On Fri, Mar 29, 2024 at 3:07 PM Chen, Jiqian <jiqian.c...@amd.com> wrote:
>
> On 2024/3/28 20:36, Michael S. Tsirkin wrote:
> >>>> +}
> >>>> +
> >>>> static void virtio_pci_bus_reset_hold(Object *obj)
> >>>> {
> >>>> PCIDevice *dev = PCI_DEVICE(obj);
> >>>> DeviceState *qdev = DEVICE(obj);
> >>>>
> >>>> + if (virtio_pci_no_soft_reset(dev)) {
> >>>> + return;
> >>>> + }
> >>>> +
> >>>> virtio_pci_reset(qdev);
> >>>>
> >>>> if (pci_is_express(dev)) {
> >>>> @@ -2484,6 +2511,8 @@ static Property virtio_pci_properties[] = {
> >>>> VIRTIO_PCI_FLAG_INIT_LNKCTL_BIT, true),
> >>>> DEFINE_PROP_BIT("x-pcie-pm-init", VirtIOPCIProxy, flags,
> >>>> VIRTIO_PCI_FLAG_INIT_PM_BIT, true),
> >>>> + DEFINE_PROP_BIT("x-pcie-pm-no-soft-reset", VirtIOPCIProxy, flags,
> >>>> + VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET_BIT, false),
Why does it come with an x prefix?
> >>>> DEFINE_PROP_BIT("x-pcie-flr-init", VirtIOPCIProxy, flags,
> >>>> VIRTIO_PCI_FLAG_INIT_FLR_BIT, true),
> >>>> DEFINE_PROP_BIT("aer", VirtIOPCIProxy, flags,
> >>>
> >>> I am a bit confused about this part.
> >>> Do you want to make this software controllable?
> >> Yes, because even the real hardware, this bit is not always set.
We are talking about emulated devices here.
> >
> > So which virtio devices should and which should not set this bit?
> This depends on the scenario the virtio-device is used, if we want to trigger
> an internal soft reset for the virtio-device during S3, this bit shouldn't be
> set.
If the device doesn't need reset, why bother the driver for this?
Btw, no_soft_reset is insufficient for some cases, there's a proposal
for the virtio-spec. I think we need to wait until it is done.
> In my use case on my environment, I don't want to reset virtio-gpu during S3,
> because once the display resources are destroyed, there are not enough
> information to re-create them, so this bit should be set.
> Making this bit software controllable is convenient for users to take their
> own choices.
Thanks
>
> >
> >>> Or should this be set to true by default and then
> >>> changed to false for old machine types?
> >> How can I do so?
> >> Do you mean set this to true by default, and if old machine types don't
> >> need this bit, they can pass false config to qemu when running qemu?
> >
> > No, you would use compat machinery. See how is x-pcie-flr-init handled.
> >
> >
>
> --
> Best regards,
> Jiqian Chen.
