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

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Message-Id: <20200908151853.4837-2-narmstrong@baylibre.com>
Date:   Tue,  8 Sep 2020 17:18:49 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     robh@...nel.org, tomeu.vizoso@...labora.com, steven.price@....com,
        alyssa.rosenzweig@...labora.com
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        Neil Armstrong <narmstrong@...libre.com>
Subject: [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 <narmstrong@...libre.com>
---
 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;
-- 
2.22.0