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xen: Add __GFP_DMA flag when xen_swiotlb_init gets free pages on ARM 

Make sure that xen_swiotlb_init allocates buffers that are DMA capable
when at least one memblock is available below 4G. Otherwise we assume
that all devices on the SoC can cope with >4G addresses. We do this on
ARM and ARM64, where dom0 is mapped 1:1, so pfn == mfn in this case.

No functional changes on x86.

From: Chen Baozi <baozich@gmail.com>

Signed-off-by: Chen Baozi <baozich@gmail.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: Chen Baozi <baozich@gmail.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Stefano Stabellini 2015-04-24 10:16:40 +01:00 committed by David Vrabel
parent a71dbdaa8c
commit 8746515d7f
4 changed files with 22 additions and 1 deletions
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1
arch/arm/include/asm/xen/page.h
View File

@ -110,5 +110,6 @@ static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
bool xen_arch_need_swiotlb(struct device *dev,
unsigned long pfn,
unsigned long mfn);
unsigned long xen_get_swiotlb_free_pages(unsigned int order);
#endif /* _ASM_ARM_XEN_PAGE_H */

15
arch/arm/xen/mm.c
View File

@ -4,6 +4,7 @@
#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/export.h>
#include <linux/memblock.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/types.h>
@ -21,6 +22,20 @@
#include <asm/xen/hypercall.h>
#include <asm/xen/interface.h>
unsigned long xen_get_swiotlb_free_pages(unsigned int order)
{
struct memblock_region *reg;
gfp_t flags = __GFP_NOWARN;
for_each_memblock(memory, reg) {
if (reg->base < (phys_addr_t)0xffffffff) {
flags |= __GFP_DMA;
break;
}
}
return __get_free_pages(flags, order);
}
enum dma_cache_op {
DMA_UNMAP,
DMA_MAP,

5
arch/x86/include/asm/xen/page.h
View File

@ -269,4 +269,9 @@ static inline bool xen_arch_need_swiotlb(struct device *dev,
return false;
}
static inline unsigned long xen_get_swiotlb_free_pages(unsigned int order)
{
return __get_free_pages(__GFP_NOWARN, order);
}
#endif /* _ASM_X86_XEN_PAGE_H */

2
drivers/xen/swiotlb-xen.c
View File

@ -235,7 +235,7 @@ int __ref xen_swiotlb_init(int verbose, bool early)
#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
xen_io_tlb_start = (void *)__get_free_pages(__GFP_NOWARN, order);
xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order);
if (xen_io_tlb_start)
break;
order--;