On Wed, 10 May 2023, Olaf Hering wrote: > Wed, 10 May 2023 00:58:27 +0200 Olaf Hering <o...@aepfle.de>: > > > In my debugging (with v8.0.0) it turned out the three pci_set_word > > causes the domU to hang. In fact, it is just the last one: > > > > pci_set_byte(pci_conf + 0x20, 0x01); /* BMIBA: 20-23h */ > > > > It changes the value from 0xc121 to 0x1. > > If I disable just "pci_set_word(pci_conf + PCI_COMMAND, 0x0000);" it works as > well. > It changes the value from 0x5 to 0. > > In general I feel it is wrong to fiddle with PCI from the host side. > This is most likely not the intention of the Xen unplug protocol. > I'm sure the guest does not expect such changes under the hood. > It happens to work by luck with pvops kernels because their PCI discovery > is done after the unplug. > > So, what do we do here to get this off the table?
I don't have a concrete suggestion because I don't understand the root cause of the issue. Looking back at Paolo's reply from 2021 https://marc.info/?l=xen-devel&m=161669099305992&w=2 I think he was right. We can either fix the root cause of the issue or avoid calling qdev_reset_all on unplug. I am OK with either one.
