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0c6874a6ac
If swiotlb is allocated, immediately return 0, so callers do not have to check io_tlb_default_mem.nslabs explicitly. Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
141 lines
3.8 KiB
C
141 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/cpu.h>
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#include <linux/dma-direct.h>
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#include <linux/dma-map-ops.h>
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#include <linux/gfp.h>
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#include <linux/highmem.h>
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#include <linux/export.h>
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#include <linux/memblock.h>
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#include <linux/of_address.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/vmalloc.h>
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#include <linux/swiotlb.h>
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#include <xen/xen.h>
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#include <xen/interface/grant_table.h>
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#include <xen/interface/memory.h>
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#include <xen/page.h>
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#include <xen/xen-ops.h>
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#include <xen/swiotlb-xen.h>
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#include <asm/cacheflush.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/interface.h>
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static gfp_t xen_swiotlb_gfp(void)
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{
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phys_addr_t base;
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u64 i;
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for_each_mem_range(i, &base, NULL) {
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if (base < (phys_addr_t)0xffffffff) {
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if (IS_ENABLED(CONFIG_ZONE_DMA32))
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return __GFP_DMA32;
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return __GFP_DMA;
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}
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}
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return GFP_KERNEL;
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}
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static bool hypercall_cflush = false;
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/* buffers in highmem or foreign pages cannot cross page boundaries */
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static void dma_cache_maint(struct device *dev, dma_addr_t handle,
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size_t size, u32 op)
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{
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struct gnttab_cache_flush cflush;
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cflush.offset = xen_offset_in_page(handle);
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cflush.op = op;
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handle &= XEN_PAGE_MASK;
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do {
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cflush.a.dev_bus_addr = dma_to_phys(dev, handle);
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if (size + cflush.offset > XEN_PAGE_SIZE)
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cflush.length = XEN_PAGE_SIZE - cflush.offset;
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else
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cflush.length = size;
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HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
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cflush.offset = 0;
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handle += cflush.length;
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size -= cflush.length;
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} while (size);
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}
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/*
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* Dom0 is mapped 1:1, and while the Linux page can span across multiple Xen
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* pages, it is not possible for it to contain a mix of local and foreign Xen
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* pages. Calling pfn_valid on a foreign mfn will always return false, so if
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* pfn_valid returns true the pages is local and we can use the native
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* dma-direct functions, otherwise we call the Xen specific version.
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*/
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void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
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size_t size, enum dma_data_direction dir)
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{
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if (dir != DMA_TO_DEVICE)
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dma_cache_maint(dev, handle, size, GNTTAB_CACHE_INVAL);
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}
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void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
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size_t size, enum dma_data_direction dir)
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{
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if (dir == DMA_FROM_DEVICE)
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dma_cache_maint(dev, handle, size, GNTTAB_CACHE_INVAL);
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else
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dma_cache_maint(dev, handle, size, GNTTAB_CACHE_CLEAN);
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}
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bool xen_arch_need_swiotlb(struct device *dev,
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phys_addr_t phys,
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dma_addr_t dev_addr)
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{
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unsigned int xen_pfn = XEN_PFN_DOWN(phys);
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unsigned int bfn = XEN_PFN_DOWN(dma_to_phys(dev, dev_addr));
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/*
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* The swiotlb buffer should be used if
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* - Xen doesn't have the cache flush hypercall
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* - The Linux page refers to foreign memory
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* - The device doesn't support coherent DMA request
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*
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* The Linux page may be spanned acrros multiple Xen page, although
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* it's not possible to have a mix of local and foreign Xen page.
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* Furthermore, range_straddles_page_boundary is already checking
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* if buffer is physically contiguous in the host RAM.
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*
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* Therefore we only need to check the first Xen page to know if we
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* require a bounce buffer because the device doesn't support coherent
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* memory and we are not able to flush the cache.
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*/
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return (!hypercall_cflush && (xen_pfn != bfn) &&
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!dev_is_dma_coherent(dev));
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}
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static int __init xen_mm_init(void)
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{
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struct gnttab_cache_flush cflush;
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int rc;
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if (!xen_swiotlb_detect())
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return 0;
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/* we can work with the default swiotlb */
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rc = swiotlb_init_late(swiotlb_size_or_default(),
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xen_swiotlb_gfp(), NULL);
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if (rc < 0)
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return rc;
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cflush.op = 0;
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cflush.a.dev_bus_addr = 0;
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cflush.offset = 0;
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cflush.length = 0;
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if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
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hypercall_cflush = true;
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return 0;
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}
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arch_initcall(xen_mm_init);
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