[PATCH v2 1/2] dma-pool: fix coherent pool allocations for IOMMU mappings

Nicolas Saenz Julienne
2020-08-03T16:10:10Z

From: Christoph Hellwig <hch@lst.de>

When allocating coherent pool memory for an IOMMU mapping we don't care
about the DMA mask. Move the guess for the initial GFP mask into the
dma_direct_alloc_pages and pass dma_coherent_ok as a function pointer
argument so that it doesn't get applied to the IOMMU case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---

Changes since v1:
- Check if phys_addr_ok() exists prior calling it

drivers/iommu/dma-iommu.c | 4 +-
include/linux/dma-direct.h | 3 -
include/linux/dma-mapping.h | 5 +-
kernel/dma/direct.c | 13 ++--
kernel/dma/pool.c | 114 +++++++++++++++---------------------
5 files changed, 62 insertions(+), 77 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 4959f5df21bd..5141d49a046b 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1035,8 +1035,8 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,

if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
!gfpflags_allow_blocking(gfp) && !coherent)
- cpu_addr = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &page,
- gfp);
+ page = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &cpu_addr,
+ gfp, NULL);
else
cpu_addr = iommu_dma_alloc_pages(dev, size, &page, gfp, attrs);
if (!cpu_addr)
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index ab2e20cba951..ba22952c24e2 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -67,9 +67,6 @@ 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/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index a33ed3954ed4..0dc08701d7b7 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -715,8 +715,9 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
pgprot_t prot, const void *caller);
void dma_common_free_remap(void *cpu_addr, size_t size);

-void *dma_alloc_from_pool(struct device *dev, size_t size,
- struct page **ret_page, gfp_t flags);
+struct page *dma_alloc_from_pool(struct device *dev, size_t size,
+ void **cpu_addr, gfp_t flags,
+ bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t));
bool dma_free_from_pool(struct device *dev, void *start, size_t size);

int
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 67f060b86a73..f17aec9d01f0 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -45,7 +45,7 @@ u64 dma_direct_get_required_mask(struct device *dev)
return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
}

-gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
+static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
u64 *phys_limit)
{
u64 dma_limit = min_not_zero(dma_mask, dev->bus_dma_limit);
@@ -70,7 +70,7 @@ gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
return 0;
}

-bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
+static 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);
@@ -163,8 +163,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
size = PAGE_ALIGN(size);

if (dma_should_alloc_from_pool(dev, gfp, attrs)) {
- ret = dma_alloc_from_pool(dev, size, &page, gfp);
- if (!ret)
+ u64 phys_mask;
+
+ gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
+ &phys_mask);
+ page = dma_alloc_from_pool(dev, size, &ret, gfp,
+ dma_coherent_ok);
+ if (!page)
return NULL;
goto done;
}
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 6bc74a2d5127..5d071d4a3cba 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -196,93 +196,75 @@ static int __init dma_atomic_pool_init(void)
}
postcore_initcall(dma_atomic_pool_init);

-static inline struct gen_pool *dma_guess_pool_from_device(struct device *dev)
+static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t gfp)
{
- u64 phys_mask;
- gfp_t gfp;
-
- gfp = dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
- &phys_mask);
- if (IS_ENABLED(CONFIG_ZONE_DMA) && gfp == GFP_DMA)
+ if (prev == NULL) {
+ if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
+ return atomic_pool_dma32;
+ if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
+ return atomic_pool_dma;
+ return atomic_pool_kernel;
+ }
+ if (prev == atomic_pool_kernel)
+ return atomic_pool_dma32 ? atomic_pool_dma32 : atomic_pool_dma;
+ if (prev == atomic_pool_dma32)
return atomic_pool_dma;
- if (IS_ENABLED(CONFIG_ZONE_DMA32) && gfp == GFP_DMA32)
- return atomic_pool_dma32;
- return atomic_pool_kernel;
+ return NULL;
}

-static inline struct gen_pool *dma_get_safer_pool(struct gen_pool *bad_pool)
+static struct page *__dma_alloc_from_pool(struct device *dev, size_t size,
+ struct gen_pool *pool, void **cpu_addr,
+ bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
{
- if (bad_pool == atomic_pool_kernel)
- return atomic_pool_dma32 ? : atomic_pool_dma;
+ unsigned long addr;
+ phys_addr_t phys;

- if (bad_pool == atomic_pool_dma32)
- return atomic_pool_dma;
+ addr = gen_pool_alloc(pool, size);
+ if (!addr)
+ return NULL;

- return NULL;
-}
+ phys = gen_pool_virt_to_phys(pool, addr);
+ if (phys_addr_ok && !phys_addr_ok(dev, phys, size)) {
+ gen_pool_free(pool, addr, size);
+ 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);
+ if (gen_pool_avail(pool) < atomic_pool_size)
+ schedule_work(&atomic_pool_work);

- return dma_guess_pool_from_device(dev);
+ *cpu_addr = (void *)addr;
+ memset(*cpu_addr, 0, size);
+ return pfn_to_page(__phys_to_pfn(phys));
}

-void *dma_alloc_from_pool(struct device *dev, size_t size,
- struct page **ret_page, gfp_t flags)
+struct page *dma_alloc_from_pool(struct device *dev, size_t size,
+ void **cpu_addr, gfp_t gfp,
+ bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
{
struct gen_pool *pool = NULL;
- unsigned long val = 0;
- void *ptr = NULL;
- phys_addr_t phys;
-
- 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;
- }
-
-
- if (val) {
- *ret_page = pfn_to_page(__phys_to_pfn(phys));
- ptr = (void *)val;
- memset(ptr, 0, size);
+ struct page *page;

- if (gen_pool_avail(pool) < atomic_pool_size)
- schedule_work(&atomic_pool_work);
+ while ((pool = dma_guess_pool(pool, gfp))) {
+ page = __dma_alloc_from_pool(dev, size, pool, cpu_addr,
+ phys_addr_ok);
+ if (page)
+ return page;
}

- return ptr;
+ WARN(1, "Failed to get suitable pool for %s\n", dev_name(dev));
+ return NULL;
}

bool dma_free_from_pool(struct device *dev, void *start, size_t size)
{
struct gen_pool *pool = NULL;

- 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;
- }
+ while ((pool = dma_guess_pool(pool, 0))) {
+ if (!gen_pool_has_addr(pool, (unsigned long)start, size))
+ continue;
+ gen_pool_free(pool, (unsigned long)start, size);
+ return true;
}
+
+ return false;
}
--
2.28.0