| Message ID | 69c934789ad2bf486b03682563ea2262ea6d9301.1568211045.git.robin.murphy@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iommu/io-pgtable-arm: Mali LPAE improvements | expand |
On 11/09/2019 15:42, Robin Murphy wrote: > In principle, Midgard GPUs supporting smaller VA sizes should only > require 3-level pagetables, since the address bits resolved at level 0 > (47:40) will never change. However, the kbase driver does not appear to > have any notion of a variable start level, and empirically T720 and T820 > rapidly blow up with translation faults unless given a full 4-level > table, despite only supporting a 33-bit VA size. Midgard 'LPAE' isn't really LPAE and does indeed always require all levels of page tables. The 33-bit VA size is really only limiting the storage of virtual addresses in the GPU and not affecting the MMU. > The 'real' IAS value is still valuable in terms of validating addresses > on map/unmap, so tweak the allocator to allow smaller values while still > forcing the resultant tables to the full 4 levels. > > Signed-off-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Steven Price <steven.price@arm.com> Steve > --- > drivers/iommu/io-pgtable-arm.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c > index 9e35cd991f06..77f41c9dd9be 100644 > --- a/drivers/iommu/io-pgtable-arm.c > +++ b/drivers/iommu/io-pgtable-arm.c > @@ -1022,7 +1022,7 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie) > if (cfg->quirks) > return NULL; > > - if (cfg->ias != 48 || cfg->oas > 40) > + if (cfg->ias > 48 || cfg->oas > 40) > return NULL; > > cfg->pgsize_bitmap &= (SZ_4K | SZ_2M | SZ_1G); > @@ -1031,6 +1031,11 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie) > if (!data) > return NULL; > > + /* Mali seems to need a full 4-level table regardless of IAS */ > + if (data->levels < ARM_LPAE_MAX_LEVELS) { > + data->levels = ARM_LPAE_MAX_LEVELS; > + data->pgd_size = sizeof(arm_lpae_iopte); > + } > /* > * MEMATTR: Mali has no actual notion of a non-cacheable type, so the > * best we can do is mimic the out-of-tree driver and hope that the >
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index 9e35cd991f06..77f41c9dd9be 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -1022,7 +1022,7 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie) if (cfg->quirks) return NULL; - if (cfg->ias != 48 || cfg->oas > 40) + if (cfg->ias > 48 || cfg->oas > 40) return NULL; cfg->pgsize_bitmap &= (SZ_4K | SZ_2M | SZ_1G); @@ -1031,6 +1031,11 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie) if (!data) return NULL; + /* Mali seems to need a full 4-level table regardless of IAS */ + if (data->levels < ARM_LPAE_MAX_LEVELS) { + data->levels = ARM_LPAE_MAX_LEVELS; + data->pgd_size = sizeof(arm_lpae_iopte); + } /* * MEMATTR: Mali has no actual notion of a non-cacheable type, so the * best we can do is mimic the out-of-tree driver and hope that the
In principle, Midgard GPUs supporting smaller VA sizes should only require 3-level pagetables, since the address bits resolved at level 0 (47:40) will never change. However, the kbase driver does not appear to have any notion of a variable start level, and empirically T720 and T820 rapidly blow up with translation faults unless given a full 4-level table, despite only supporting a 33-bit VA size. The 'real' IAS value is still valuable in terms of validating addresses on map/unmap, so tweak the allocator to allow smaller values while still forcing the resultant tables to the full 4 levels. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/iommu/io-pgtable-arm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)