Re: [PATCH 1/5] iommu/io-pgtable-arm: Add BROKEN_NS quirk to disable shareability on ARM LPAE

The coherency integration of the IOMMU in the Mali-G52 found in the Amlogic G12B SoCs
is broken and leads to constant and random faults from the IOMMU.

Disabling shareability completely fixes the issue.

Signed-off-by: Neil Armstrong <redacted>
---
  drivers/iommu/io-pgtable-arm.c | 7 ++++---
  include/linux/io-pgtable.h     | 4 ++++
  2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index dc7bcf858b6d..d2d48dc86556 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c

@@ -440,7 +440,9 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
  				<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
  	}
  
-	if (prot & IOMMU_CACHE)
+	if (data->iop.cfg.quirks & IO_PGTABLE_QUIRK_ARM_BROKEN_SH)
+		pte |= ARM_LPAE_PTE_SH_NS;
+	else if (prot & IOMMU_CACHE)
  		pte |= ARM_LPAE_PTE_SH_IS;
  	else
  		pte |= ARM_LPAE_PTE_SH_OS;

@@ -1005,8 +1007,7 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
  {
  	struct arm_lpae_io_pgtable *data;
  
-	/* No quirks for Mali (hopefully) */
-	if (cfg->quirks)
+	if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_BROKEN_SH))
  		return NULL;
  
  	if (cfg->ias > 48 || cfg->oas > 40)

diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 23285ba645db..efb9c8f20909 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h

@@ -86,6 +86,9 @@ struct io_pgtable_cfg {
  	 *
  	 * IO_PGTABLE_QUIRK_ARM_TTBR1: (ARM LPAE format) Configure the table
  	 *	for use in the upper half of a split address space.
+	 *
+	 * IO_PGTABLE_QUIRK_ARM_BROKEN_SH: (ARM LPAE format) Disables shareability
+	 *	when coherency integration is broken.
  	 */
  	#define IO_PGTABLE_QUIRK_ARM_NS		BIT(0)
  	#define IO_PGTABLE_QUIRK_NO_PERMS	BIT(1)

@@ -93,6 +96,7 @@ struct io_pgtable_cfg {
  	#define IO_PGTABLE_QUIRK_ARM_MTK_EXT	BIT(3)
  	#define IO_PGTABLE_QUIRK_NON_STRICT	BIT(4)
  	#define IO_PGTABLE_QUIRK_ARM_TTBR1	BIT(5)
+	#define IO_PGTABLE_QUIRK_ARM_BROKEN_SH	BIT(6)
  	unsigned long			quirks;
  	unsigned long			pgsize_bitmap;
  	unsigned int			ias;