Commit 8746515d authored by Stefano Stabellini's avatar Stefano Stabellini Committed by David Vrabel
Browse files

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 <>
Signed-off-by: default avatarChen Baozi <>
Signed-off-by: default avatarStefano Stabellini <>
Tested-by: default avatarChen Baozi <>
Acked-by: default avatarKonrad Rzeszutek Wilk <>
Signed-off-by: default avatarDavid Vrabel <>
parent a71dbdaa
......@@ -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 */
......@@ -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;
return __get_free_pages(flags, order);
enum dma_cache_op {
......@@ -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 */
......@@ -235,7 +235,7 @@ retry:
#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)
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