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xen/arm: simplify dma_cache_maint

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Calculate the required operation in the caller, and pass it directly
instead of recalculating it for each page, and use simple arithmetics
to get from the physical address to Xen page size aligned chunks.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
This commit is contained in:
Christoph Hellwig 2019-07-24 15:26:08 +02:00
parent a8e6d950cd
commit efcd5729d9
1 changed files with 20 additions and 39 deletions
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57
arch/arm/xen/mm.c
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@ -35,64 +35,45 @@ unsigned long xen_get_swiotlb_free_pages(unsigned int order)
return __get_free_pages(flags, order);
}
enum dma_cache_op {
DMA_UNMAP,
DMA_MAP,
};
static bool hypercall_cflush = false;
/* functions called by SWIOTLB */
static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
size_t size, enum dma_data_direction dir, enum dma_cache_op op)
/* buffers in highmem or foreign pages cannot cross page boundaries */
static void dma_cache_maint(dma_addr_t handle, size_t size, u32 op)
{
struct gnttab_cache_flush cflush;
unsigned long xen_pfn;
size_t left = size;
xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE;
offset %= XEN_PAGE_SIZE;
cflush.a.dev_bus_addr = handle & XEN_PAGE_MASK;
cflush.offset = xen_offset_in_page(handle);
cflush.op = op;
do {
size_t len = left;
/* buffers in highmem or foreign pages cannot cross page
* boundaries */
if (len + offset > XEN_PAGE_SIZE)
len = XEN_PAGE_SIZE - offset;
cflush.op = 0;
cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT;
cflush.offset = offset;
cflush.length = len;
if (op == DMA_UNMAP && dir != DMA_TO_DEVICE)
cflush.op = GNTTAB_CACHE_INVAL;
if (op == DMA_MAP) {
if (dir == DMA_FROM_DEVICE)
cflush.op = GNTTAB_CACHE_INVAL;
if (size + cflush.offset > XEN_PAGE_SIZE)
cflush.length = XEN_PAGE_SIZE - cflush.offset;
else
cflush.op = GNTTAB_CACHE_CLEAN;
}
if (cflush.op)
cflush.length = size;
HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
offset = 0;
xen_pfn++;
left -= len;
} while (left);
cflush.offset = 0;
cflush.a.dev_bus_addr += cflush.length;
size -= cflush.length;
} while (size);
}
static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
if (dir != DMA_TO_DEVICE)
dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
}
static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
if (dir == DMA_FROM_DEVICE)
dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
else
dma_cache_maint(handle, size, GNTTAB_CACHE_CLEAN);
}
void __xen_dma_map_page(struct device *hwdev, struct page *page,