iommu/io-pgtable: Add DART subpage protection support

DART allows to only expose a subpage to the device. While this is an
optional feature on the M1 DARTs the new ones present on the Pro/Max
models require this field in every PTE.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20220916094152.87137-4-j@jannau.net
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/io-pgtable-dart.c b/drivers/iommu/io-pgtable-dart.c
index 8ca1ea313a8089deb2ff4b49e7150facbc85b2b3..fc76b6168055680fd6a00f70830a92ba86803406 100644 (file)
--- a/drivers/iommu/io-pgtable-dart.c
+++ b/drivers/iommu/io-pgtable-dart.c
@@ -14,6 +14,7 @@
 #define pr_fmt(fmt)    "dart io-pgtable: " fmt
 
 #include <linux/atomic.h>
+#include <linux/bitfield.h>
 #include <linux/bitops.h>
 #include <linux/io-pgtable.h>
 #include <linux/kernel.h>
@@ -40,6 +41,9 @@
 #define DART_PTES_PER_TABLE(d)                                 \
        (DART_GRANULE(d) >> ilog2(sizeof(dart_iopte)))
 
+#define APPLE_DART_PTE_SUBPAGE_START   GENMASK_ULL(63, 52)
+#define APPLE_DART_PTE_SUBPAGE_END     GENMASK_ULL(51, 40)
+
 #define APPLE_DART1_PADDR_MASK GENMASK_ULL(35, 12)
 
 /* Apple DART1 protection bits */
@@ -107,6 +111,10 @@ static int dart_init_pte(struct dart_io_pgtable *data,
                        return -EEXIST;
                }
 
+       /* subpage protection: always allow access to the entire page */
+       pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_START, 0);
+       pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_END, 0xfff);
+
        pte |= APPLE_DART1_PTE_PROT_SP_DIS;
        pte |= APPLE_DART_PTE_VALID;