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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/cpu.h>
#include <linux/dma-direct.h>
#include <linux/dma-map-ops.h>
#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>
#include <linux/vmalloc.h>
#include <linux/swiotlb.h>
#include <xen/xen.h>
#include <xen/interface/grant_table.h>
#include <xen/interface/memory.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/swiotlb-xen.h>
#include <asm/cacheflush.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/interface.h>
static gfp_t xen_swiotlb_gfp(void)
{
phys_addr_t base;
u64 i;
for_each_mem_range(i, &base, NULL) {
if (base < (phys_addr_t)0xffffffff) {
if (IS_ENABLED(CONFIG_ZONE_DMA32))
return __GFP_DMA32;
return __GFP_DMA;
}
}
return GFP_KERNEL;
}
static bool hypercall_cflush = false;
/* buffers in highmem or foreign pages cannot cross page boundaries */
static void dma_cache_maint(struct device *dev, dma_addr_t handle,
size_t size, u32 op)
{
struct gnttab_cache_flush cflush;
cflush.offset = xen_offset_in_page(handle);
cflush.op = op;
handle &= XEN_PAGE_MASK;
do {
cflush.a.dev_bus_addr = dma_to_phys(dev, handle);
if (size + cflush.offset > XEN_PAGE_SIZE)
cflush.length = XEN_PAGE_SIZE - cflush.offset;
else
cflush.length = size;
HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
cflush.offset = 0;
handle += cflush.length;
size -= cflush.length;
} while (size);
}
/*
* Dom0 is mapped 1:1, and while the Linux page can span across multiple Xen
* pages, it is not possible for it to contain a mix of local and foreign Xen
* pages. Calling pfn_valid on a foreign mfn will always return false, so if
* pfn_valid returns true the pages is local and we can use the native
* dma-direct functions, otherwise we call the Xen specific version.
*/
void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
if (dir != DMA_TO_DEVICE)
dma_cache_maint(dev, handle, size, GNTTAB_CACHE_INVAL);
}
void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
if (dir == DMA_FROM_DEVICE)
dma_cache_maint(dev, handle, size, GNTTAB_CACHE_INVAL);
else
dma_cache_maint(dev, handle, size, GNTTAB_CACHE_CLEAN);
}
bool xen_arch_need_swiotlb(struct device *dev,
phys_addr_t phys,
dma_addr_t dev_addr)
{
unsigned int xen_pfn = XEN_PFN_DOWN(phys);
unsigned int bfn = XEN_PFN_DOWN(dma_to_phys(dev, dev_addr));
/*
* The swiotlb buffer should be used if
* - Xen doesn't have the cache flush hypercall
* - The Linux page refers to foreign memory
* - The device doesn't support coherent DMA request
*
* The Linux page may be spanned acrros multiple Xen page, although
* it's not possible to have a mix of local and foreign Xen page.
* Furthermore, range_straddles_page_boundary is already checking
* if buffer is physically contiguous in the host RAM.
*
* Therefore we only need to check the first Xen page to know if we
* require a bounce buffer because the device doesn't support coherent
* memory and we are not able to flush the cache.
*/
return (!hypercall_cflush && (xen_pfn != bfn) &&
!dev_is_dma_coherent(dev));
}
static int __init xen_mm_init(void)
{
struct gnttab_cache_flush cflush;
int rc;
if (!xen_swiotlb_detect())
return 0;
/* we can work with the default swiotlb */
if (!io_tlb_default_mem.nslabs) {
rc = swiotlb_init_late(swiotlb_size_or_default(),
xen_swiotlb_gfp(), NULL);
if (rc < 0)
return rc;
}
cflush.op = 0;
cflush.a.dev_bus_addr = 0;
cflush.offset = 0;
cflush.length = 0;
if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
hypercall_cflush = true;
return 0;
}
arch_initcall(xen_mm_init);
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