Thread (16 messages) flat view 16 messages, 4 authors, 2020-09-09

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

From: Neil Armstrong <hidden>
Date: 2020-09-09 12:54:39
Also in: dri-devel, linux-amlogic, lkml

On 09/09/2020 14:23, Steven Price wrote:
Subject: s/BROKEN_NS/BROKEN_SH/
Thanks,
Neil
Steve

On 08/09/2020 16:18, Neil Armstrong wrote:
quoted
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;

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