From 567f6a6eba0c09e5f502e0290e57651befa8aacb Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne Date: Tue, 14 Jul 2020 14:39:25 +0200 Subject: [PATCH 1/5] dma-direct: provide function to check physical memory area validity dma_coherent_ok() checks if a physical memory area fits a device's DMA constraints. Signed-off-by: Nicolas Saenz Julienne Signed-off-by: Christoph Hellwig --- include/linux/dma-direct.h | 1 + kernel/dma/direct.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h index 5184735a0fe8..ab2e20cba951 100644 --- a/include/linux/dma-direct.h +++ b/include/linux/dma-direct.h @@ -69,6 +69,7 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, u64 dma_direct_get_required_mask(struct device *dev); gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask, u64 *phys_mask); +bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size); void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs); void dma_direct_free(struct device *dev, size_t size, void *cpu_addr, diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 95866b647581..67f060b86a73 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -70,7 +70,7 @@ gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask, return 0; } -static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) +bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) { return phys_to_dma_direct(dev, phys) + size - 1 <= min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit); From 23e469be6239d9cf3d921fc3e38545491df56534 Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne Date: Tue, 14 Jul 2020 14:39:26 +0200 Subject: [PATCH 2/5] dma-pool: get rid of dma_in_atomic_pool() The function is only used once and can be simplified to a one-liner. Signed-off-by: Nicolas Saenz Julienne Signed-off-by: Christoph Hellwig --- kernel/dma/pool.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 39ca26fa41b5..318035e093fb 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -217,15 +217,6 @@ static inline struct gen_pool *dev_to_pool(struct device *dev) return atomic_pool_kernel; } -static bool dma_in_atomic_pool(struct device *dev, void *start, size_t size) -{ - struct gen_pool *pool = dev_to_pool(dev); - - if (unlikely(!pool)) - return false; - return gen_pool_has_addr(pool, (unsigned long)start, size); -} - void *dma_alloc_from_pool(struct device *dev, size_t size, struct page **ret_page, gfp_t flags) { @@ -260,7 +251,7 @@ bool dma_free_from_pool(struct device *dev, void *start, size_t size) { struct gen_pool *pool = dev_to_pool(dev); - if (!dma_in_atomic_pool(dev, start, size)) + if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size)) return false; gen_pool_free(pool, (unsigned long)start, size); return true; From 48b6703858dd5526c82d8ff2dbac59acab3a9dda Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne Date: Tue, 14 Jul 2020 14:39:27 +0200 Subject: [PATCH 3/5] dma-pool: introduce dma_guess_pool() dma-pool's dev_to_pool() creates the false impression that there is a way to grantee a mapping between a device's DMA constraints and an atomic pool. It tuns out it's just a guess, and the device might need to use an atomic pool containing memory from a 'safer' (or lower) memory zone. To help mitigate this, introduce dma_guess_pool() which can be fed a device's DMA constraints and atomic pools already known to be faulty, in order for it to provide an better guess on which pool to use. Signed-off-by: Nicolas Saenz Julienne Signed-off-by: Christoph Hellwig --- kernel/dma/pool.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 318035e093fb..5b9eaa2b498d 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -203,7 +203,7 @@ static int __init dma_atomic_pool_init(void) } postcore_initcall(dma_atomic_pool_init); -static inline struct gen_pool *dev_to_pool(struct device *dev) +static inline struct gen_pool *dma_guess_pool_from_device(struct device *dev) { u64 phys_mask; gfp_t gfp; @@ -217,10 +217,30 @@ static inline struct gen_pool *dev_to_pool(struct device *dev) return atomic_pool_kernel; } +static inline struct gen_pool *dma_get_safer_pool(struct gen_pool *bad_pool) +{ + if (bad_pool == atomic_pool_kernel) + return atomic_pool_dma32 ? : atomic_pool_dma; + + if (bad_pool == atomic_pool_dma32) + return atomic_pool_dma; + + return NULL; +} + +static inline struct gen_pool *dma_guess_pool(struct device *dev, + struct gen_pool *bad_pool) +{ + if (bad_pool) + return dma_get_safer_pool(bad_pool); + + return dma_guess_pool_from_device(dev); +} + void *dma_alloc_from_pool(struct device *dev, size_t size, struct page **ret_page, gfp_t flags) { - struct gen_pool *pool = dev_to_pool(dev); + struct gen_pool *pool = dma_guess_pool(dev, NULL); unsigned long val; void *ptr = NULL; @@ -249,7 +269,7 @@ void *dma_alloc_from_pool(struct device *dev, size_t size, bool dma_free_from_pool(struct device *dev, void *start, size_t size) { - struct gen_pool *pool = dev_to_pool(dev); + struct gen_pool *pool = dma_guess_pool(dev, NULL); if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size)) return false; From 81e9d894e03f9a279102c7aac62ea7cbf9949f4b Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne Date: Tue, 14 Jul 2020 14:39:28 +0200 Subject: [PATCH 4/5] dma-pool: make sure atomic pool suits device When allocating DMA memory from a pool, the core can only guess which atomic pool will fit a device's constraints. If it doesn't, get a safer atomic pool and try again. Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp mask") Reported-by: Jeremy Linton Suggested-by: Robin Murphy Signed-off-by: Nicolas Saenz Julienne Signed-off-by: Christoph Hellwig --- kernel/dma/pool.c | 55 +++++++++++++++++++++++++++++++---------------- 1 file changed, 36 insertions(+), 19 deletions(-) diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 5b9eaa2b498d..d48d9acb585f 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -240,39 +240,56 @@ static inline struct gen_pool *dma_guess_pool(struct device *dev, void *dma_alloc_from_pool(struct device *dev, size_t size, struct page **ret_page, gfp_t flags) { - struct gen_pool *pool = dma_guess_pool(dev, NULL); - unsigned long val; + struct gen_pool *pool = NULL; + unsigned long val = 0; void *ptr = NULL; + phys_addr_t phys; - if (!pool) { - WARN(1, "%pGg atomic pool not initialised!\n", &flags); - return NULL; + while (1) { + pool = dma_guess_pool(dev, pool); + if (!pool) { + WARN(1, "Failed to get suitable pool for %s\n", + dev_name(dev)); + break; + } + + val = gen_pool_alloc(pool, size); + if (!val) + continue; + + phys = gen_pool_virt_to_phys(pool, val); + if (dma_coherent_ok(dev, phys, size)) + break; + + gen_pool_free(pool, val, size); + val = 0; } - val = gen_pool_alloc(pool, size); - if (likely(val)) { - phys_addr_t phys = gen_pool_virt_to_phys(pool, val); + if (val) { *ret_page = pfn_to_page(__phys_to_pfn(phys)); ptr = (void *)val; memset(ptr, 0, size); - } else { - WARN_ONCE(1, "DMA coherent pool depleted, increase size " - "(recommended min coherent_pool=%zuK)\n", - gen_pool_size(pool) >> 9); + + if (gen_pool_avail(pool) < atomic_pool_size) + schedule_work(&atomic_pool_work); } - if (gen_pool_avail(pool) < atomic_pool_size) - schedule_work(&atomic_pool_work); return ptr; } bool dma_free_from_pool(struct device *dev, void *start, size_t size) { - struct gen_pool *pool = dma_guess_pool(dev, NULL); + struct gen_pool *pool = NULL; - if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size)) - return false; - gen_pool_free(pool, (unsigned long)start, size); - return true; + while (1) { + pool = dma_guess_pool(dev, pool); + if (!pool) + return false; + + if (gen_pool_has_addr(pool, (unsigned long)start, size)) { + gen_pool_free(pool, (unsigned long)start, size); + return true; + } + } } From d9765e41d8e9ea2251bf73735a2895c8bad546fc Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne Date: Wed, 8 Jul 2020 18:49:39 +0200 Subject: [PATCH 5/5] dma-pool: do not allocate pool memory from CMA There is no guarantee to CMA's placement, so allocating a zone specific atomic pool from CMA might return memory from a completely different memory zone. So stop using it. Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp mask") Reported-by: Jeremy Linton Signed-off-by: Nicolas Saenz Julienne Tested-by: Jeremy Linton Acked-by: David Rientjes Signed-off-by: Christoph Hellwig --- kernel/dma/pool.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index d48d9acb585f..6bc74a2d5127 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -6,7 +6,6 @@ #include #include #include -#include #include #include #include @@ -69,12 +68,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, do { pool_size = 1 << (PAGE_SHIFT + order); - - if (dev_get_cma_area(NULL)) - page = dma_alloc_from_contiguous(NULL, 1 << order, - order, false); - else - page = alloc_pages(gfp, order); + page = alloc_pages(gfp, order); } while (!page && order-- > 0); if (!page) goto out; @@ -118,8 +112,7 @@ remove_mapping: dma_common_free_remap(addr, pool_size); #endif free_page: __maybe_unused - if (!dma_release_from_contiguous(NULL, page, 1 << order)) - __free_pages(page, order); + __free_pages(page, order); out: return ret; }