drivers/iommu/io-pgtable-arm.c | 27 ++++++++++++++------------- include/linux/io-pgtable.h | 8 ++++++++ 2 files changed, 22 insertions(+), 13 deletions(-)
From: Rob Clark <robdclark@chromium.org>
In situations where mapping/unmapping sequence 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.
Now that there is a quirk, we can also drop the selftest_running
flag, and use the quirk instead for selftests.
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
Sending v2 stand-alone, since I'm not quite ready to send a new
iteration of the full VM_BIND series. And with selftest_running
removed, I think this patch stands on it's own. (And maybe there
is still time to sneak this in for v6.16, removing an iommu dep
for the VM_BIND series in v6.17?)
v2: Drop selftest_running and use IO_PGTABLE_QUIRK_NO_WARN_ON for
the selftests
drivers/iommu/io-pgtable-arm.c | 27 ++++++++++++++-------------
include/linux/io-pgtable.h | 8 ++++++++
2 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index f27965caf6a1..a535d88f8943 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -253,8 +253,6 @@ static inline bool arm_lpae_concat_mandatory(struct io_pgtable_cfg *cfg,
(data->start_level == 1) && (oas == 40);
}
-static bool selftest_running = false;
-
static dma_addr_t __arm_lpae_dma_addr(void *pages)
{
return (dma_addr_t)virt_to_phys(pages);
@@ -373,7 +371,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
for (i = 0; i < num_entries; i++)
if (iopte_leaf(ptep[i], lvl, data->iop.fmt)) {
/* We require an unmap first */
- WARN_ON(!selftest_running);
+ WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON));
return -EEXIST;
} else if (iopte_type(ptep[i]) == ARM_LPAE_PTE_TYPE_TABLE) {
/*
@@ -475,7 +473,7 @@ 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(!(cfg->quirks & IO_PGTABLE_QUIRK_NO_WARN_ON));
return -EEXIST;
}
@@ -649,8 +647,10 @@ 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 +660,10 @@ 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 +978,8 @@ 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 +1082,8 @@ 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);
@@ -1320,7 +1324,6 @@ static void __init arm_lpae_dump_ops(struct io_pgtable_ops *ops)
#define __FAIL(ops, i) ({ \
WARN(1, "selftest: test failed for fmt idx %d\n", (i)); \
arm_lpae_dump_ops(ops); \
- selftest_running = false; \
-EFAULT; \
})
@@ -1336,8 +1339,6 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg)
size_t size, mapped;
struct io_pgtable_ops *ops;
- selftest_running = true;
-
for (i = 0; i < ARRAY_SIZE(fmts); ++i) {
cfg_cookie = cfg;
ops = alloc_io_pgtable_ops(fmts[i], cfg, cfg);
@@ -1426,7 +1427,6 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg)
free_io_pgtable_ops(ops);
}
- selftest_running = false;
return 0;
}
@@ -1448,6 +1448,7 @@ static int __init arm_lpae_do_selftests(void)
.tlb = &dummy_tlb_ops,
.coherent_walk = true,
.iommu_dev = &dev,
+ .quirks = IO_PGTABLE_QUIRK_NO_WARN_ON,
};
/* __arm_lpae_alloc_pages() merely needs dev_to_node() to work */
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;
--
2.49.0On 07/05/2025 3:29 pm, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> In situations where mapping/unmapping sequence 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.
>
> Now that there is a quirk, we can also drop the selftest_running
> flag, and use the quirk instead for selftests.
Acked-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
> Sending v2 stand-alone, since I'm not quite ready to send a new
> iteration of the full VM_BIND series. And with selftest_running
> removed, I think this patch stands on it's own. (And maybe there
> is still time to sneak this in for v6.16, removing an iommu dep
> for the VM_BIND series in v6.17?)
>
> v2: Drop selftest_running and use IO_PGTABLE_QUIRK_NO_WARN_ON for
> the selftests
>
> drivers/iommu/io-pgtable-arm.c | 27 ++++++++++++++-------------
> include/linux/io-pgtable.h | 8 ++++++++
> 2 files changed, 22 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index f27965caf6a1..a535d88f8943 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -253,8 +253,6 @@ static inline bool arm_lpae_concat_mandatory(struct io_pgtable_cfg *cfg,
> (data->start_level == 1) && (oas == 40);
> }
>
> -static bool selftest_running = false;
> -
> static dma_addr_t __arm_lpae_dma_addr(void *pages)
> {
> return (dma_addr_t)virt_to_phys(pages);
> @@ -373,7 +371,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
> for (i = 0; i < num_entries; i++)
> if (iopte_leaf(ptep[i], lvl, data->iop.fmt)) {
> /* We require an unmap first */
> - WARN_ON(!selftest_running);
> + WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON));
> return -EEXIST;
> } else if (iopte_type(ptep[i]) == ARM_LPAE_PTE_TYPE_TABLE) {
> /*
> @@ -475,7 +473,7 @@ 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(!(cfg->quirks & IO_PGTABLE_QUIRK_NO_WARN_ON));
> return -EEXIST;
> }
>
> @@ -649,8 +647,10 @@ 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 +660,10 @@ 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 +978,8 @@ 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 +1082,8 @@ 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);
> @@ -1320,7 +1324,6 @@ static void __init arm_lpae_dump_ops(struct io_pgtable_ops *ops)
> #define __FAIL(ops, i) ({ \
> WARN(1, "selftest: test failed for fmt idx %d\n", (i)); \
> arm_lpae_dump_ops(ops); \
> - selftest_running = false; \
> -EFAULT; \
> })
>
> @@ -1336,8 +1339,6 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg)
> size_t size, mapped;
> struct io_pgtable_ops *ops;
>
> - selftest_running = true;
> -
> for (i = 0; i < ARRAY_SIZE(fmts); ++i) {
> cfg_cookie = cfg;
> ops = alloc_io_pgtable_ops(fmts[i], cfg, cfg);
> @@ -1426,7 +1427,6 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg)
> free_io_pgtable_ops(ops);
> }
>
> - selftest_running = false;
> return 0;
> }
>
> @@ -1448,6 +1448,7 @@ static int __init arm_lpae_do_selftests(void)
> .tlb = &dummy_tlb_ops,
> .coherent_walk = true,
> .iommu_dev = &dev,
> + .quirks = IO_PGTABLE_QUIRK_NO_WARN_ON,
> };
>
> /* __arm_lpae_alloc_pages() merely needs dev_to_node() to work */
> 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;
On Wed, May 07, 2025 at 07:29:51AM -0700, Rob Clark wrote: > From: Rob Clark <robdclark@chromium.org> > > In situations where mapping/unmapping sequence 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. > > Now that there is a quirk, we can also drop the selftest_running > flag, and use the quirk instead for selftests. > > Signed-off-by: Rob Clark <robdclark@chromium.org> > --- > Sending v2 stand-alone, since I'm not quite ready to send a new > iteration of the full VM_BIND series. And with selftest_running > removed, I think this patch stands on it's own. (And maybe there > is still time to sneak this in for v6.16, removing an iommu dep > for the VM_BIND series in v6.17?) You should just remove the warn on completely, no other driver does this. Jason
On 07/05/2025 3:40 pm, Jason Gunthorpe wrote: > On Wed, May 07, 2025 at 07:29:51AM -0700, Rob Clark wrote: >> From: Rob Clark <robdclark@chromium.org> >> >> In situations where mapping/unmapping sequence 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. >> >> Now that there is a quirk, we can also drop the selftest_running >> flag, and use the quirk instead for selftests. >> >> Signed-off-by: Rob Clark <robdclark@chromium.org> >> --- >> Sending v2 stand-alone, since I'm not quite ready to send a new >> iteration of the full VM_BIND series. And with selftest_running >> removed, I think this patch stands on it's own. (And maybe there >> is still time to sneak this in for v6.16, removing an iommu dep >> for the VM_BIND series in v6.17?) > > You should just remove the warn on completely, no other driver does this. What do you mean "no other driver"? From a quick look, these IOMMU drivers have some sort of visible warning related to the state of an existing PTE during map/unmap: apple-dart arm-smmu arm-smmu-v3 arm-smmu-qcom exynos-iommu ipmmu_vmsa msm_iommu mtk_iommu rockchip-iommu s390-iommu sun50i-iommu qcom_iommu while these IOMMU drivers do not: amd intel mtk_iommu_v1 omap-iommu riscv sprd-iommu tegra-smmu virtio-iommu By driver count, warning is literally the majority behaviour :/ Thanks, Robin.
On Wed, May 07, 2025 at 04:09:47PM +0100, Robin Murphy wrote: > On 07/05/2025 3:40 pm, Jason Gunthorpe wrote: > > On Wed, May 07, 2025 at 07:29:51AM -0700, Rob Clark wrote: > > > From: Rob Clark <robdclark@chromium.org> > > > > > > In situations where mapping/unmapping sequence 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. > > > > > > Now that there is a quirk, we can also drop the selftest_running > > > flag, and use the quirk instead for selftests. > > > > > > Signed-off-by: Rob Clark <robdclark@chromium.org> > > > --- > > > Sending v2 stand-alone, since I'm not quite ready to send a new > > > iteration of the full VM_BIND series. And with selftest_running > > > removed, I think this patch stands on it's own. (And maybe there > > > is still time to sneak this in for v6.16, removing an iommu dep > > > for the VM_BIND series in v6.17?) > > > > You should just remove the warn on completely, no other driver does this. > > What do you mean "no other driver"? The server drivers. > From a quick look, these IOMMU drivers have some sort of visible warning > related to the state of an existing PTE during map/unmap: Many of them are just using this code. > while these IOMMU drivers do not: > > amd > intel > mtk_iommu_v1 > omap-iommu > riscv > sprd-iommu > tegra-smmu > virtio-iommu Which I think proves we don't need it and shouldn't have it. Jason
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