Commit 3318f7b5 authored by Rob Clark's avatar Rob Clark Committed by Will Deacon
Browse files

iommu/io-pgtable-arm: Add quirk to quiet WARN_ON() 



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: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarRob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20250519175348.11924-6-robdclark@gmail.com


[will: Rename quirk to IO_PGTABLE_QUIRK_NO_WARN per Robin's suggestion]
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent be5a2d3f

drivers/iommu/io-pgtable-arm.c

+14 −13
Original line number Diff line number Diff line
@@ -251,8 +251,6 @@ 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);
@@ -371,7 +369,7 @@ 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));

			return -EEXIST;

		} else if (iopte_type(ptep[i]) == ARM_LPAE_PTE_TYPE_TABLE) {

			/*
@@ -473,7 +471,7 @@ 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));

		return -EEXIST;

	}
@@ -641,8 +639,10 @@ 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));

		return -ENOENT;

	}



	/* If the size matches this level, we're in the right place */

	if (size == ARM_LPAE_BLOCK_SIZE(lvl, data)) {
@@ -652,8 +652,10 @@ 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));

				break;

			}



			if (!iopte_leaf(pte, lvl, iop->fmt)) {

				__arm_lpae_clear_pte(&ptep[i], &iop->cfg, 1);
@@ -968,7 +970,8 @@ 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))

		return NULL;



	data = arm_lpae_alloc_pgtable(cfg);
@@ -1069,7 +1072,8 @@ 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))

		return NULL;



	data = arm_lpae_alloc_pgtable(cfg);
@@ -1310,7 +1314,6 @@ 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;						\

})
@@ -1326,8 +1329,6 @@ 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);
@@ -1416,7 +1417,6 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg) 
		free_io_pgtable_ops(ops);

	}



	selftest_running = false;

	return 0;

}
@@ -1438,6 +1438,7 @@ static int __init arm_lpae_do_selftests(void) 
		.tlb = &dummy_tlb_ops,

		.coherent_walk = true,

		.iommu_dev = &dev,

		.quirks = IO_PGTABLE_QUIRK_NO_WARN,

	};



	/* __arm_lpae_alloc_pages() merely needs dev_to_node() to work */

include/linux/io-pgtable.h

+8 −0
Original line number Diff line number Diff line
@@ -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: 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		BIT(9)

	unsigned long			quirks;

	unsigned long			pgsize_bitmap;

	unsigned int			ias;