On 03.02.2022 14:50, Roger Pau Monné wrote: > On Thu, Feb 03, 2022 at 12:55:56PM +0100, Jan Beulich wrote: >> On 03.02.2022 12:06, Roger Pau Monne wrote: >>> Prevent libxl from creating guests that attempts to use PoD together >>> with an IOMMU, even if no devices are actually assigned. >>> >>> While the hypervisor could support using PoD together with an IOMMU as >>> long as no devices are assigned, such usage seems doubtful. There's no >>> guarantee the guest has ballooned down enough memory for PoD to no >>> longer be active, and thus a later assignment of a PCI device to such >>> domain could fail. >> >> That's not a precise description of the constraint: The guest ballooning >> down enough only means entries == cache, but for device assignment we >> need entries == 0 (and a guarantee that no new entries can appear, but I >> think this is already the case once a guest was launched). > > Would you be OK with: > > "While the hypervisor could support using PoD together with an IOMMU as > long as no devices are assigned, such usage seems doubtful. There's no > guarantee the guest has PoD no longer be active, and thus a later > assignment of a PCI device to such domain could fail."
Yes, thanks, this sounds better (to me at least). Jan
