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> > > > + if (unlikely(sz_lg2 > 52)) > > > > + return (CMD_INV_IOMMU_ALL_PAGES_ADDRESS & PAGE_MASK) | > > > > + CMD_INV_IOMMU_PAGES_SIZE_MASK; > > > > I was looking at Ankit's series and thinking this is slightly better as: > > > > + if (unlikely(sz_lg2 > min(52, BITS_PER_LONG - 1))) > > > > So a ULONG_MAX gather will trigger full invalidation on 32 bit as > > well, though it shouldn't be necessary it seems a tish cleaner and > > matches how vt-d ended up > > > > I see the value in matching how VT‑d handles this. I’m slightly concerned > that adding the BITS_PER_LONG check might imply that AMD‑IOMMU supports > 32‑bit kernels. > > Unlike VT‑d, the AMD IOMMU driver doesn’t build on 32‑bit at all. From > Kconfig: > > config AMD_IOMMU > depends on X86_64 && PCI && ACPI && HAVE_CMPXCHG_DOUBLE > > config INTEL_IOMMU > depends on PCI_MSI && ACPI && X86 > > Given that the 32‑bit case is unreachable for AMD‑IOMMU, keeping the > existing check might actually be clearer? Ah, I didn't remember that, it makes sense. Let's leave it then Jason