340720be32
xen_dma_unmap_page, xen_dma_sync_single_for_cpu and xen_dma_sync_single_for_device are currently implemented by calling into the corresponding generic ARM implementation of these functions. In order to do this, firstly the dma_addr_t handle, that on Xen is a machine address, needs to be translated into a physical address. The operation is expensive and inaccurate, given that a single machine address can correspond to multiple physical addresses in one domain, because the same page can be granted multiple times by the frontend. To avoid this problem, we introduce a Xen specific implementation of xen_dma_unmap_page, xen_dma_sync_single_for_cpu and xen_dma_sync_single_for_device, that can operate on machine addresses directly. The new implementation relies on the fact that the hypervisor creates a second p2m mapping of any grant pages at physical address == machine address of the page for dom0. Therefore we can access memory at physical address == dma_addr_r handle and perform the cache flushing there. Some cache maintenance operations require a virtual address. Instead of using ioremap_cache, that is not safe in interrupt context, we allocate a per-cpu PAGE_KERNEL scratch page and we manually update the pte for it. arm64 doesn't need cache maintenance operations on unmap for now. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Tested-by: Denis Schneider <v1ne2go@gmail.com>
40 lines
1.3 KiB
C
40 lines
1.3 KiB
C
#ifndef _ASM_ARM_XEN_PAGE_COHERENT_H
|
|
#define _ASM_ARM_XEN_PAGE_COHERENT_H
|
|
|
|
#include <asm/page.h>
|
|
#include <linux/dma-attrs.h>
|
|
#include <linux/dma-mapping.h>
|
|
|
|
static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
|
|
dma_addr_t *dma_handle, gfp_t flags,
|
|
struct dma_attrs *attrs)
|
|
{
|
|
return __generic_dma_ops(hwdev)->alloc(hwdev, size, dma_handle, flags, attrs);
|
|
}
|
|
|
|
static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
|
|
void *cpu_addr, dma_addr_t dma_handle,
|
|
struct dma_attrs *attrs)
|
|
{
|
|
__generic_dma_ops(hwdev)->free(hwdev, size, cpu_addr, dma_handle, attrs);
|
|
}
|
|
|
|
static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
|
|
unsigned long offset, size_t size, enum dma_data_direction dir,
|
|
struct dma_attrs *attrs)
|
|
{
|
|
__generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);
|
|
}
|
|
|
|
void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
|
|
size_t size, enum dma_data_direction dir,
|
|
struct dma_attrs *attrs);
|
|
|
|
void xen_dma_sync_single_for_cpu(struct device *hwdev,
|
|
dma_addr_t handle, size_t size, enum dma_data_direction dir);
|
|
|
|
void xen_dma_sync_single_for_device(struct device *hwdev,
|
|
dma_addr_t handle, size_t size, enum dma_data_direction dir);
|
|
|
|
#endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */
|