On Tue, Mar 28, 2023 at 9:28 AM Roger Pau Monné <[email protected]> wrote: > > On Tue, Mar 28, 2023 at 03:23:56PM +0200, Jan Beulich wrote: > > On 28.03.2023 15:04, Marek Marczykowski-Górecki wrote: > > > On Tue, Mar 28, 2023 at 02:54:38PM +0200, Jan Beulich wrote: > > >> On 25.03.2023 03:49, Marek Marczykowski-Górecki wrote: > > >>> Some firmware/devices are found to not reset MSI-X properly, leaving > > >>> MASKALL set. Xen relies on initial state being both disabled. > > >>> Especially, pci_reset_msix_state() assumes if MASKALL is set, it was Xen > > >>> setting it due to msix->host_maskall or msix->guest_maskall. Clearing > > >>> just MASKALL might be unsafe if ENABLE is set, so clear them both. > > >> > > >> But pci_reset_msix_state() comes into play only when assigning a device > > >> to a DomU. If the tool stack doing a reset doesn't properly clear the > > >> bit, how would it be cleared the next time round (i.e. after the guest > > >> stopped and then possibly was started again)? It feels like the issue > > >> wants dealing with elsewhere, possibly in the tool stack. > > > > > > I may be misremembering some details, but AFAIR Xen intercepts > > > toolstack's (or more generally: accesses from dom0) attempt to clean > > > this up and once it enters an inconsistent state (or rather: starts with > > > such at the start of the day), there was no way to clean it up. > > > > Iirc Roger and you already discussed that there needs to be an > > indication of device reset having happened, so that Xen can resync > > from this "behind its back" operation. That would look to be the > > point/place where such inconsistencies should be eliminated. > > I think that was a different conversation with Huang Rui related to > the AMD GPU work, see: > > https://lore.kernel.org/xen-devel/ZBwtaceTNvCYksmR@Air-de-Roger/ > > I understood the problem Marek was trying to solve was that some > devices where initialized with the MASKALL bit set (likely by the > firmware?) and that prevented Xen from using them. But now seeing the > further replies on this patch I'm unsure whether that's the case.
In my case, Xen's setting of MASKALL persists through a warm reboot, so Xen sees it set when booting. On a cold boot, MASKALL is not set. Regards, Jason
