Re: [PATCH v11 1/2] virtio-pci: only reset pm state during resetting

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

On Fri, Jun 21, 2024 at 09:19:11AM +0000, Chen, Jiqian wrote:
> Hi MST,
> 
> On 2024/6/6 18:22, Jiqian Chen wrote:
> > Fix bug imported by 27ce0f3afc9dd ("fix Power Management Control Register for PCI Express virtio devices"
> > After this change, observe that QEMU may erroneously clear the power status of the device,
> > or may erroneously clear non writable registers, such as NO_SOFT_RESET, etc.
> > 
> > Only state of PM_CTRL is writable.
> > Only when flag VIRTIO_PCI_FLAG_INIT_PM is set, need to reset state.
> > 
> > Fixes: 27ce0f3afc9dd ("fix Power Management Control Register for PCI Express virtio devices"
> > 
> > Signed-off-by: Jiqian Chen <Jiqian.Chen@amd.com>
> > ---
> >  hw/virtio/virtio-pci.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index b1d02f4b3de0..1b63bcb3f15c 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -2300,10 +2300,16 @@ static void virtio_pci_bus_reset_hold(Object *obj, ResetType type)
> >      virtio_pci_reset(qdev);
> >  
> >      if (pci_is_express(dev)) {
> > +        VirtIOPCIProxy *proxy = VIRTIO_PCI(dev);
> > +
> >          pcie_cap_deverr_reset(dev);
> >          pcie_cap_lnkctl_reset(dev);
> >  
> > -        pci_set_word(dev->config + dev->exp.pm_cap + PCI_PM_CTRL, 0);
> > +        if (proxy->flags & VIRTIO_PCI_FLAG_INIT_PM) {
> > +            pci_word_test_and_clear_mask(
> > +                dev->config + dev->exp.pm_cap + PCI_PM_CTRL,
> > +                PCI_PM_CTRL_STATE_MASK);
> > +        }
> >      }
> >  }
> >  
> I noticed that you merged this patch into the staging before, but then reverted it. Do you still have any concerns?
> 
> -- 
> Best regards,
> Jiqian Chen.

Sorry I don't remember at this point. Normally it's because of
test failures but I then also notify the authors ... 
I will try to re-merge and see.

-- 
MST