[PATCH v4 12/14] swiotlb: Add restricted DMA alloc/free support.

Claire Chang
2021-02-09T06:30:22Z

Add the functions, dev_swiotlb_{alloc,free} to support the memory
allocation from restricted DMA pool.

Signed-off-by: Claire Chang <tientzu@chromium.org>
---
include/linux/swiotlb.h | 2 ++
kernel/dma/direct.c | 30 ++++++++++++++++++++++--------
kernel/dma/swiotlb.c | 34 ++++++++++++++++++++++++++++++++++
3 files changed, 58 insertions(+), 8 deletions(-)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index b9f2a250c8da..2cd39e102915 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -74,6 +74,8 @@ extern enum swiotlb_force swiotlb_force;
#ifdef CONFIG_DMA_RESTRICTED_POOL
bool is_swiotlb_force(struct device *dev);
bool is_dev_swiotlb_force(struct device *dev);
+struct page *dev_swiotlb_alloc(struct device *dev, size_t size, gfp_t gfp);
+bool dev_swiotlb_free(struct device *dev, struct page *page, size_t size);
#else
static inline bool is_swiotlb_force(struct device *dev)
{
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index a76a1a2f24da..f9a9321f7559 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -12,6 +12,7 @@
#include <linux/pfn.h>
#include <linux/vmalloc.h>
#include <linux/set_memory.h>
+#include <linux/swiotlb.h>
#include <linux/slab.h>
#include "direct.h"

@@ -77,6 +78,10 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)

static void __dma_direct_free_pages(struct device *dev, struct page *page, size_t size)
{
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+ if (dev_swiotlb_free(dev, page, size))
+ return;
+#endif
dma_free_contiguous(dev, page, size);
}

@@ -89,6 +94,12 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,

WARN_ON_ONCE(!PAGE_ALIGNED(size));

+#ifdef CONFIG_DMA_RESTRICTED_POOL
+ page = dev_swiotlb_alloc(dev, size, gfp);
+ if (page)
+ return page;
+#endif
+
gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
&phys_limit);
page = dma_alloc_contiguous(dev, size, gfp);
@@ -147,7 +158,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
gfp |= __GFP_NOWARN;

if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
- !force_dma_unencrypted(dev)) {
+ !force_dma_unencrypted(dev) && !is_dev_swiotlb_force(dev)) {
page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
if (!page)
return NULL;
@@ -160,8 +171,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
}

if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
- !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
- !dev_is_dma_coherent(dev))
+ !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && !dev_is_dma_coherent(dev) &&
+ !is_dev_swiotlb_force(dev))
return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);

/*
@@ -171,7 +182,9 @@ void *dma_direct_alloc(struct device *dev, size_t size,
if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
!gfpflags_allow_blocking(gfp) &&
(force_dma_unencrypted(dev) ||
- (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && !dev_is_dma_coherent(dev))))
+ (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
+ !dev_is_dma_coherent(dev))) &&
+ !is_dev_swiotlb_force(dev))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);

/* we always manually zero the memory once we are done */
@@ -252,15 +265,15 @@ void dma_direct_free(struct device *dev, size_t size,
unsigned int page_order = get_order(size);

if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
- !force_dma_unencrypted(dev)) {
+ !force_dma_unencrypted(dev) && !is_dev_swiotlb_force(dev)) {
/* cpu_addr is a struct page cookie, not a kernel address */
dma_free_contiguous(dev, cpu_addr, size);
return;
}

if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
- !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
- !dev_is_dma_coherent(dev)) {
+ !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && !dev_is_dma_coherent(dev) &&
+ !is_dev_swiotlb_force(dev)) {
arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
return;
}
@@ -288,7 +301,8 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
void *ret;

if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
- force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp))
+ force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
+ !is_dev_swiotlb_force(dev))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);

page = __dma_direct_alloc_pages(dev, size, gfp);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index fd9c1bd183ac..8b77fd64199e 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -836,6 +836,40 @@ late_initcall(swiotlb_create_default_debugfs);
#endif

#ifdef CONFIG_DMA_RESTRICTED_POOL
+struct page *dev_swiotlb_alloc(struct device *dev, size_t size, gfp_t gfp)
+{
+ struct swiotlb *swiotlb;
+ phys_addr_t tlb_addr;
+ unsigned int index;
+
+ /* dev_swiotlb_alloc can be used only in the context which permits sleeping. */
+ if (!dev->dev_swiotlb || !gfpflags_allow_blocking(gfp))
+ return NULL;
+
+ swiotlb = dev->dev_swiotlb;
+ index = swiotlb_tbl_find_free_region(dev, swiotlb->start, size, 0);
+ if (index < 0)
+ return NULL;
+
+ tlb_addr = swiotlb->start + (index << IO_TLB_SHIFT);
+
+ return pfn_to_page(PFN_DOWN(tlb_addr));
+}
+
+bool dev_swiotlb_free(struct device *dev, struct page *page, size_t size)
+{
+ unsigned int index;
+ phys_addr_t tlb_addr = page_to_phys(page);
+
+ if (!is_swiotlb_buffer(dev, tlb_addr))
+ return false;
+
+ index = (tlb_addr - dev->dev_swiotlb->start) >> IO_TLB_SHIFT;
+ swiotlb_tbl_release_region(dev, index, size);
+
+ return true;
+}
+
bool is_swiotlb_force(struct device *dev)
{
return unlikely(swiotlb_force == SWIOTLB_FORCE) || dev->dev_swiotlb;
--
2.30.0.478.g8a0d178c01-goog