On Mon, Dec 07, 2015 at 12:09:56PM +0000, Robin Murphy wrote: > On 07/12/15 11:08, Will Deacon wrote: > [...] > >>+#define ARM_LPAE_GRANULE(d) (1UL << (d)->pg_shift) > >>+ > >> #define ARM_LPAE_PAGES_PER_PGD(d) \ > >>- DIV_ROUND_UP((d)->pgd_size, 1UL << (d)->pg_shift) > >>+ DIV_ROUND_UP((d)->pgd_size, ARM_LPAE_GRANULE(d)) > >> > >> /* > >> * Calculate the index at level l used to map virtual address a using the > >>@@ -169,7 +171,7 @@ > >> /* IOPTE accessors */ > >> #define iopte_deref(pte,d) \ > >> (__va((pte) & ((1ULL << ARM_LPAE_MAX_ADDR_BITS) - 1) \ > >>- & ~((1ULL << (d)->pg_shift) - 1))) > >>+ & ~(ARM_LPAE_GRANULE(d) - 1))) > > > >Do we run the risk of truncating the VA on 32-bit ARM here? > > Indeed, in all honesty I'd missed that, but since __va is going to truncate > it to a 32-bit void * anyway, doing it earlier in the expression actually > seems to result in better code - with iopte_deref wrapped like so to make it > easier to pick out:
Gah, I meant PA not VA, sorry. The PA is 40-bit, but with ARM_LPAE_GRANULE using unsigned long, we drop the top 8 bits of the output address field in the pte. Will _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
