Re: [PATCH] x86: enable DMA CMA with swiotlb
From: Marek Szyprowski
Date: Fri Nov 22 2013 - 04:15:44 EST
Hello,
On 2013-11-20 00:32, Akinobu Mita wrote:
The DMA Contiguous Memory Allocator support on x86 is disabled when
swiotlb config option is enabled. So DMA CMA is always disabled on
x86_64 because swiotlb is always enabled. This attempts to support
for DMA CMA with enabling swiotlb config option.
The contiguous memory allocator on x86 is integrated in the function
dma_generic_alloc_coherent() which is .alloc callback in nommu_dma_ops
for dma_alloc_coherent().
x86_swiotlb_alloc_coherent() which is .alloc callback in swiotlb_dma_ops
tries to allocate with dma_generic_alloc_coherent() firstly and then
swiotlb_alloc_coherent() is called as a fallback.
The main part of supporting DMA CMA with swiotlb is that changing
x86_swiotlb_free_coherent() which is .free callback in swiotlb_dma_ops
for dma_free_coherent() so that it can distinguish memory allocated by
dma_generic_alloc_coherent() from one allocated by swiotlb_alloc_coherent()
and release it with dma_generic_free_coherent() which can handle contiguous
memory. This change requires making is_swiotlb_buffer() global function.
This also needs to change .free callback in the dma_map_ops for amd_gart
and sta2x11, because these dma_ops are also using
dma_generic_alloc_coherent().
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Acked-by: Marek Szyprowski<m.szyprowski@xxxxxxxxxxx>
---
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/swiotlb.h | 7 +++++++
arch/x86/kernel/amd_gart_64.c | 2 +-
arch/x86/kernel/pci-swiotlb.c | 9 ++++++---
arch/x86/pci/sta2x11-fixup.c | 6 ++----
include/linux/swiotlb.h | 2 ++
lib/swiotlb.c | 2 +-
7 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e903c71..b15df8b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -39,7 +39,7 @@ config X86
select ARCH_WANT_OPTIONAL_GPIOLIB
select ARCH_WANT_FRAME_POINTERS
select HAVE_DMA_ATTRS
- select HAVE_DMA_CONTIGUOUS if !SWIOTLB
+ select HAVE_DMA_CONTIGUOUS
select HAVE_KRETPROBES
select HAVE_OPTPROBES
select HAVE_KPROBES_ON_FTRACE
diff --git a/arch/x86/include/asm/swiotlb.h b/arch/x86/include/asm/swiotlb.h
index 977f176..ab05d73 100644
--- a/arch/x86/include/asm/swiotlb.h
+++ b/arch/x86/include/asm/swiotlb.h
@@ -29,4 +29,11 @@ static inline void pci_swiotlb_late_init(void)
static inline void dma_mark_clean(void *addr, size_t size) {}
+extern void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
+ dma_addr_t *dma_handle, gfp_t flags,
+ struct dma_attrs *attrs);
+extern void x86_swiotlb_free_coherent(struct device *dev, size_t size,
+ void *vaddr, dma_addr_t dma_addr,
+ struct dma_attrs *attrs);
+
#endif /* _ASM_X86_SWIOTLB_H */
diff --git a/arch/x86/kernel/amd_gart_64.c b/arch/x86/kernel/amd_gart_64.c
index b574b29..8e3842f 100644
--- a/arch/x86/kernel/amd_gart_64.c
+++ b/arch/x86/kernel/amd_gart_64.c
@@ -512,7 +512,7 @@ gart_free_coherent(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_addr, struct dma_attrs *attrs)
{
gart_unmap_page(dev, dma_addr, size, DMA_BIDIRECTIONAL, NULL);
- free_pages((unsigned long)vaddr, get_order(size));
+ dma_generic_free_coherent(dev, size, vaddr, dma_addr, attrs);
}
static int gart_mapping_error(struct device *dev, dma_addr_t dma_addr)
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index 6c483ba..77dd0ad 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -14,7 +14,7 @@
#include <asm/iommu_table.h>
int swiotlb __read_mostly;
-static void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
+void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
dma_addr_t *dma_handle, gfp_t flags,
struct dma_attrs *attrs)
{
@@ -28,11 +28,14 @@ static void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
return swiotlb_alloc_coherent(hwdev, size, dma_handle, flags);
}
-static void x86_swiotlb_free_coherent(struct device *dev, size_t size,
+void x86_swiotlb_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_addr,
struct dma_attrs *attrs)
{
- swiotlb_free_coherent(dev, size, vaddr, dma_addr);
+ if (is_swiotlb_buffer(dma_to_phys(dev, dma_addr)))
+ swiotlb_free_coherent(dev, size, vaddr, dma_addr);
+ else
+ dma_generic_free_coherent(dev, size, vaddr, dma_addr, attrs);
}
static struct dma_map_ops swiotlb_dma_ops = {
diff --git a/arch/x86/pci/sta2x11-fixup.c b/arch/x86/pci/sta2x11-fixup.c
index 9d8a509..5ceda85 100644
--- a/arch/x86/pci/sta2x11-fixup.c
+++ b/arch/x86/pci/sta2x11-fixup.c
@@ -173,9 +173,7 @@ static void *sta2x11_swiotlb_alloc_coherent(struct device *dev,
{
void *vaddr;
- vaddr = dma_generic_alloc_coherent(dev, size, dma_handle, flags, attrs);
- if (!vaddr)
- vaddr = swiotlb_alloc_coherent(dev, size, dma_handle, flags);
+ vaddr = x86_swiotlb_alloc_coherent(dev, size, dma_handle, flags, attrs);
*dma_handle = p2a(*dma_handle, to_pci_dev(dev));
return vaddr;
}
@@ -183,7 +181,7 @@ static void *sta2x11_swiotlb_alloc_coherent(struct device *dev,
/* We have our own dma_ops: the same as swiotlb but from alloc (above) */
static struct dma_map_ops sta2x11_dma_ops = {
.alloc = sta2x11_swiotlb_alloc_coherent,
- .free = swiotlb_free_coherent,
+ .free = x86_swiotlb_free_coherent,
.map_page = swiotlb_map_page,
.unmap_page = swiotlb_unmap_page,
.map_sg = swiotlb_map_sg_attrs,
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index a5ffd32..e7a018e 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -116,4 +116,6 @@ static inline void swiotlb_free(void) { }
#endif
extern void swiotlb_print_info(void);
+extern int is_swiotlb_buffer(phys_addr_t paddr);
+
#endif /* __LINUX_SWIOTLB_H */
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index fe978e0..6e4a798 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -369,7 +369,7 @@ void __init swiotlb_free(void)
io_tlb_nslabs = 0;
}
-static int is_swiotlb_buffer(phys_addr_t paddr)
+int is_swiotlb_buffer(phys_addr_t paddr)
{
return paddr >= io_tlb_start && paddr < io_tlb_end;
}
Best regards
--
Marek Szyprowski
Samsung R&D Institute Poland
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