iommu/io-pgtable-arm: Support all Mali configurations

In principle, Midgard GPUs supporting smaller VA sizes should only
require 3-level pagetables, since level 0 only resolves bits 48:40 of
the address. 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. As far as I can test,
this should make all known Midgard variants happy.

Fixes: d08d42de6432 ("iommu: io-pgtable: Add ARM Mali midgard MMU page table format")
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 90cb37a..ca51036 100644 (file)
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -1024,7 +1024,7 @@ 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);
@@ -1033,6 +1033,11 @@ 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