Commit 83862ccf authored by Stefano Stabellini's avatar Stefano Stabellini

xen/arm,arm64: enable SWIOTLB_XEN

Xen on arm and arm64 needs SWIOTLB_XEN: when running on Xen we need to
program the hardware with mfns rather than pfns for dma addresses.
Remove SWIOTLB_XEN dependency on X86 and PCI and make XEN select
SWIOTLB_XEN on arm and arm64.

At the moment always rely on swiotlb-xen, but when Xen starts supporting
hardware IOMMUs we'll be able to avoid it conditionally on the presence
of an IOMMU on the platform.

Implement xen_create_contiguous_region on arm and arm64: for the moment
we assume that dom0 has been mapped 1:1 (physical addresses == machine
addresses) therefore we don't need to call XENMEM_exchange. Simply
return the physical address as dma address.

Initialize the xen-swiotlb from xen_early_init (before the native
dma_ops are initialized), set xen_dma_ops to &xen_swiotlb_dma_ops.
Signed-off-by: default avatarStefano Stabellini <>

Changes in v8:
- assume dom0 is mapped 1:1, no need to call XENMEM_exchange.

Changes in v7:
- call __set_phys_to_machine_multi from xen_create_contiguous_region and
xen_destroy_contiguous_region to update the P2M;
- don't call XENMEM_unpin, it has been removed;
- call XENMEM_exchange instead of XENMEM_exchange_and_pin;
- set nr_exchanged to 0 before calling the hypercall.

Changes in v6:
- introduce and export xen_dma_ops;
- call xen_mm_init from as arch_initcall.

Changes in v4:
- remove redefinition of DMA_ERROR_CODE;
- update the code to use XENMEM_exchange_and_pin and XENMEM_unpin;
- add a note about hardware IOMMU in the commit message.

Changes in v3:
- code style changes;
- warn on XENMEM_put_dma_buf failures.
parent 69908907
......@@ -1888,6 +1888,7 @@ config XEN
depends on CPU_V7 && !CPU_V6
depends on !GENERIC_ATOMIC64
select ARM_PSCI
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
......@@ -16,4 +16,6 @@ static inline enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
extern struct dma_map_ops *xen_dma_ops;
......@@ -6,6 +6,7 @@
#include <linux/pfn.h>
#include <linux/types.h>
#include <linux/dma-mapping.h>
#include <xen/xen.h>
#include <xen/interface/grant_table.h>
obj-y := enlighten.o hypercall.o grant-table.o p2m.o
obj-y := enlighten.o hypercall.o grant-table.o p2m.o mm.o
#include <linux/bootmem.h>
#include <linux/gfp.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/dma-mapping.h>
#include <linux/vmalloc.h>
#include <linux/swiotlb.h>
#include <xen/xen.h>
#include <xen/interface/memory.h>
#include <xen/swiotlb-xen.h>
#include <asm/cacheflush.h>
#include <asm/xen/page.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/interface.h>
int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
unsigned int address_bits,
dma_addr_t *dma_handle)
if (!xen_initial_domain())
return -EINVAL;
/* we assume that dom0 is mapped 1:1 for now */
*dma_handle = virt_to_phys(pstart);
return 0;
void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
struct dma_map_ops *xen_dma_ops;
static struct dma_map_ops xen_swiotlb_dma_ops = {
.mapping_error = xen_swiotlb_dma_mapping_error,
.alloc = xen_swiotlb_alloc_coherent,
.free = xen_swiotlb_free_coherent,
.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
.sync_single_for_device = xen_swiotlb_sync_single_for_device,
.sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
.sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
.map_sg = xen_swiotlb_map_sg_attrs,
.unmap_sg = xen_swiotlb_unmap_sg_attrs,
.map_page = xen_swiotlb_map_page,
.unmap_page = xen_swiotlb_unmap_page,
.dma_supported = xen_swiotlb_dma_supported,
int __init xen_mm_init(void)
if (!xen_initial_domain())
return 0;
xen_swiotlb_init(1, false);
xen_dma_ops = &xen_swiotlb_dma_ops;
return 0;
......@@ -211,6 +211,7 @@ config XEN_DOM0
config XEN
bool "Xen guest support on ARM64 (EXPERIMENTAL)"
depends on ARM64 && OF
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.
xen-arm-y += $(addprefix ../../arm/xen/, enlighten.o grant-table.o p2m.o)
xen-arm-y += $(addprefix ../../arm/xen/, enlighten.o grant-table.o p2m.o mm.o)
obj-y := xen-arm.o hypercall.o
......@@ -140,7 +140,6 @@ config XEN_GRANT_DEV_ALLOC
def_bool y
depends on PCI && X86
select SWIOTLB
config XEN_TMEM
......@@ -42,12 +42,27 @@
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/hvc-console.h>
#include <asm/dma-mapping.h>
* Used to do a quick range check in swiotlb_tbl_unmap_single and
* swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
* API.
#ifndef CONFIG_X86
static unsigned long dma_alloc_coherent_mask(struct device *dev,
gfp_t gfp)
unsigned long dma_mask = 0;
dma_mask = dev->coherent_dma_mask;
if (!dma_mask)
dma_mask = (gfp & GFP_DMA) ? DMA_BIT_MASK(24) : DMA_BIT_MASK(32);
return dma_mask;
static char *xen_io_tlb_start, *xen_io_tlb_end;
static unsigned long xen_io_tlb_nslabs;
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