From: Rob Clark <robdcl...@chromium.org>
In situations where mapping/unmapping squence can be controlled by
userspace, attempting to map over a region that has not yet been
unmapped is an error. But not something that should spam dmesg.
Signed-off-by: Rob Clark <robdcl...@chromium.org>
---
drivers/iommu/io-pgtable-arm.c | 18 ++++++++++++------
include/linux/io-pgtable.h | 8 ++++++++
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index f27965caf6a1..99523505dac5 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -475,7 +475,7 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data,
unsigned long iova,
cptep = iopte_deref(pte, data);
} else if (pte) {
/* We require an unmap first */
- WARN_ON(!selftest_running);
+ WARN_ON(!selftest_running && !(cfg->quirks &
IO_PGTABLE_QUIRK_NO_WARN_ON));
return -EEXIST;
}
@@ -649,8 +649,10 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable
*data,
unmap_idx_start = ARM_LPAE_LVL_IDX(iova, lvl, data);
ptep += unmap_idx_start;
pte = READ_ONCE(*ptep);
- if (WARN_ON(!pte))
- return 0;
+ if (!pte) {
+ WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON));
+ return -ENOENT;
+ }
/* If the size matches this level, we're in the right place */
if (size == ARM_LPAE_BLOCK_SIZE(lvl, data)) {
@@ -660,8 +662,10 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable
*data,
/* Find and handle non-leaf entries */
for (i = 0; i < num_entries; i++) {
pte = READ_ONCE(ptep[i]);
- if (WARN_ON(!pte))
+ if (!pte) {
+ WARN_ON(!(data->iop.cfg.quirks &
IO_PGTABLE_QUIRK_NO_WARN_ON));
break;
+ }
if (!iopte_leaf(pte, lvl, iop->fmt)) {
__arm_lpae_clear_pte(&ptep[i], &iop->cfg, 1);
@@ -976,7 +980,8 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg,
void *cookie)
if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
IO_PGTABLE_QUIRK_ARM_TTBR1 |
IO_PGTABLE_QUIRK_ARM_OUTER_WBWA |
- IO_PGTABLE_QUIRK_ARM_HD))
+ IO_PGTABLE_QUIRK_ARM_HD |
+ IO_PGTABLE_QUIRK_NO_WARN_ON))
return NULL;
data = arm_lpae_alloc_pgtable(cfg);
@@ -1079,7 +1084,8 @@ arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg,
void *cookie)
struct arm_lpae_io_pgtable *data;
typeof(&cfg->arm_lpae_s2_cfg.vtcr) vtcr = &cfg->arm_lpae_s2_cfg.vtcr;
- if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_S2FWB))
+ if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_S2FWB |
+ IO_PGTABLE_QUIRK_NO_WARN_ON))
return NULL;
data = arm_lpae_alloc_pgtable(cfg);
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index bba2a51c87d2..639b8f4fb87d 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -88,6 +88,13 @@ struct io_pgtable_cfg {
*
* IO_PGTABLE_QUIRK_ARM_HD: Enables dirty tracking in stage 1 pagetable.
* IO_PGTABLE_QUIRK_ARM_S2FWB: Use the FWB format for the MemAttrs bits
+ *
+ * IO_PGTABLE_QUIRK_NO_WARN_ON: Do not WARN_ON() on conflicting
+ * mappings, but silently return -EEXISTS. Normally an attempt
+ * to map over an existing mapping would indicate some sort of
+ * kernel bug, which would justify the WARN_ON(). But for GPU
+ * drivers, this could be under control of userspace. Which
+ * deserves an error return, but not to spam dmesg.
*/
#define IO_PGTABLE_QUIRK_ARM_NS BIT(0)
#define IO_PGTABLE_QUIRK_NO_PERMS BIT(1)
@@ -97,6 +104,7 @@ struct io_pgtable_cfg {
#define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA BIT(6)
#define IO_PGTABLE_QUIRK_ARM_HD BIT(7)
#define IO_PGTABLE_QUIRK_ARM_S2FWB BIT(8)
+ #define IO_PGTABLE_QUIRK_NO_WARN_ON BIT(9)
unsigned long quirks;
unsigned long pgsize_bitmap;
unsigned int ias;
--
2.49.0
