iommu/io-pgtable-arm: Correct Mali attributes

Whilst Midgard's MEMATTR follows a similar principle to the VMSA MAIR,
the actual attribute values differ, so although it currently appears to
work to some degree, we probably shouldn't be using our standard stage 1
MAIR for that. Instead, generate a reasonable MEMATTR with attribute
values borrowed from the kbase driver; at this point we'll be overriding
or ignoring pretty much all of the LPAE config, so just implement these
Mali details in a dedicated allocator instead of pretending to subclass
the standard VMSA format.

Fixes: d08d42de ("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>

drivers/iommu/io-pgtable-arm.c

@@ -166,6 +166,9 @@
 #define ARM_MALI_LPAE_TTBR_READ_INNER	BIT(2)
 #define ARM_MALI_LPAE_TTBR_SHARE_OUTER	BIT(4)
 
+#define ARM_MALI_LPAE_MEMATTR_IMP_DEF	0x88ULL
+#define ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC 0x8DULL
+
 /* IOPTE accessors */
 #define iopte_deref(pte,d) __va(iopte_to_paddr(pte, d))
 
@@ -1015,27 +1018,51 @@ arm_32_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
 static struct io_pgtable *
 arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
 {
-	struct io_pgtable *iop;
+	struct arm_lpae_io_pgtable *data;
+
+	/* No quirks for Mali (hopefully) */
+	if (cfg->quirks)
+		return NULL;
 
 	if (cfg->ias != 48 || cfg->oas > 40)
 		return NULL;
 
 	cfg->pgsize_bitmap &= (SZ_4K | SZ_2M | SZ_1G);
-	iop = arm_64_lpae_alloc_pgtable_s1(cfg, cookie);
-	if (iop) {
-		u64 mair, ttbr;
 
-		/* Copy values as union fields overlap */
-		mair = cfg->arm_lpae_s1_cfg.mair[0];
-		ttbr = cfg->arm_lpae_s1_cfg.ttbr[0];
+	data = arm_lpae_alloc_pgtable(cfg);
+	if (!data)
+		return NULL;
 
-		cfg->arm_mali_lpae_cfg.memattr = mair;
-		cfg->arm_mali_lpae_cfg.transtab = ttbr |
-			ARM_MALI_LPAE_TTBR_READ_INNER |
-			ARM_MALI_LPAE_TTBR_ADRMODE_TABLE;
-	}
+	/*
+	 * 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
+	 * "implementation-defined caching policy" is good enough. Similarly,
+	 * we'll use it for the sake of a valid attribute for our 'device'
+	 * index, although callers should never request that in practice.
+	 */
+	cfg->arm_mali_lpae_cfg.memattr =
+		(ARM_MALI_LPAE_MEMATTR_IMP_DEF
+		 << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_NC)) |
+		(ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC
+		 << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_CACHE)) |
+		(ARM_MALI_LPAE_MEMATTR_IMP_DEF
+		 << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_DEV));
 
-	return iop;
+	data->pgd = __arm_lpae_alloc_pages(data->pgd_size, GFP_KERNEL, cfg);
+	if (!data->pgd)
+		goto out_free_data;
+
+	/* Ensure the empty pgd is visible before TRANSTAB can be written */
+	wmb();
+
+	cfg->arm_mali_lpae_cfg.transtab = virt_to_phys(data->pgd) |
+					  ARM_MALI_LPAE_TTBR_READ_INNER |
+					  ARM_MALI_LPAE_TTBR_ADRMODE_TABLE;
+	return &data->iop;
+
+out_free_data:
+	kfree(data);
+	return NULL;
 }
 
 struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {