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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright 2010
- * by Konrad Rzeszutek Wilk <[email protected]>
- *
- * This code provides a IOMMU for Xen PV guests with PCI passthrough.
- *
- * PV guests under Xen are running in an non-contiguous memory architecture.
- *
- * When PCI pass-through is utilized, this necessitates an IOMMU for
- * translating bus (DMA) to virtual and vice-versa and also providing a
- * mechanism to have contiguous pages for device drivers operations (say DMA
- * operations).
- *
- * Specifically, under Xen the Linux idea of pages is an illusion. It
- * assumes that pages start at zero and go up to the available memory. To
- * help with that, the Linux Xen MMU provides a lookup mechanism to
- * translate the page frame numbers (PFN) to machine frame numbers (MFN)
- * and vice-versa. The MFN are the "real" frame numbers. Furthermore
- * memory is not contiguous. Xen hypervisor stitches memory for guests
- * from different pools, which means there is no guarantee that PFN==MFN
- * and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are
- * allocated in descending order (high to low), meaning the guest might
- * never get any MFN's under the 4GB mark.
- */
- #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
- #include <linux/memblock.h>
- #include <linux/dma-direct.h>
- #include <linux/dma-map-ops.h>
- #include <linux/export.h>
- #include <xen/swiotlb-xen.h>
- #include <xen/page.h>
- #include <xen/xen-ops.h>
- #include <xen/hvc-console.h>
- #include <asm/dma-mapping.h>
- #include <trace/events/swiotlb.h>
- #define MAX_DMA_BITS 32
- /*
- * Quick lookup value of the bus address of the IOTLB.
- */
- static inline phys_addr_t xen_phys_to_bus(struct device *dev, phys_addr_t paddr)
- {
- unsigned long bfn = pfn_to_bfn(XEN_PFN_DOWN(paddr));
- phys_addr_t baddr = (phys_addr_t)bfn << XEN_PAGE_SHIFT;
- baddr |= paddr & ~XEN_PAGE_MASK;
- return baddr;
- }
- static inline dma_addr_t xen_phys_to_dma(struct device *dev, phys_addr_t paddr)
- {
- return phys_to_dma(dev, xen_phys_to_bus(dev, paddr));
- }
- static inline phys_addr_t xen_bus_to_phys(struct device *dev,
- phys_addr_t baddr)
- {
- unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr));
- phys_addr_t paddr = (xen_pfn << XEN_PAGE_SHIFT) |
- (baddr & ~XEN_PAGE_MASK);
- return paddr;
- }
- static inline phys_addr_t xen_dma_to_phys(struct device *dev,
- dma_addr_t dma_addr)
- {
- return xen_bus_to_phys(dev, dma_to_phys(dev, dma_addr));
- }
- static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
- {
- unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p);
- unsigned int i, nr_pages = XEN_PFN_UP(xen_offset_in_page(p) + size);
- next_bfn = pfn_to_bfn(xen_pfn);
- for (i = 1; i < nr_pages; i++)
- if (pfn_to_bfn(++xen_pfn) != ++next_bfn)
- return 1;
- return 0;
- }
- static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr)
- {
- unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr));
- unsigned long xen_pfn = bfn_to_local_pfn(bfn);
- phys_addr_t paddr = (phys_addr_t)xen_pfn << XEN_PAGE_SHIFT;
- /* If the address is outside our domain, it CAN
- * have the same virtual address as another address
- * in our domain. Therefore _only_ check address within our domain.
- */
- if (pfn_valid(PFN_DOWN(paddr)))
- return is_swiotlb_buffer(dev, paddr);
- return 0;
- }
- #ifdef CONFIG_X86
- int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
- {
- int rc;
- unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT);
- unsigned int i, dma_bits = order + PAGE_SHIFT;
- dma_addr_t dma_handle;
- phys_addr_t p = virt_to_phys(buf);
- BUILD_BUG_ON(IO_TLB_SEGSIZE & (IO_TLB_SEGSIZE - 1));
- BUG_ON(nslabs % IO_TLB_SEGSIZE);
- i = 0;
- do {
- do {
- rc = xen_create_contiguous_region(
- p + (i << IO_TLB_SHIFT), order,
- dma_bits, &dma_handle);
- } while (rc && dma_bits++ < MAX_DMA_BITS);
- if (rc)
- return rc;
- i += IO_TLB_SEGSIZE;
- } while (i < nslabs);
- return 0;
- }
- static void *
- xen_swiotlb_alloc_coherent(struct device *dev, size_t size,
- dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
- {
- u64 dma_mask = dev->coherent_dma_mask;
- int order = get_order(size);
- phys_addr_t phys;
- void *ret;
- /* Align the allocation to the Xen page size */
- size = 1UL << (order + XEN_PAGE_SHIFT);
- ret = (void *)__get_free_pages(flags, get_order(size));
- if (!ret)
- return ret;
- phys = virt_to_phys(ret);
- *dma_handle = xen_phys_to_dma(dev, phys);
- if (*dma_handle + size - 1 > dma_mask ||
- range_straddles_page_boundary(phys, size)) {
- if (xen_create_contiguous_region(phys, order, fls64(dma_mask),
- dma_handle) != 0)
- goto out_free_pages;
- SetPageXenRemapped(virt_to_page(ret));
- }
- memset(ret, 0, size);
- return ret;
- out_free_pages:
- free_pages((unsigned long)ret, get_order(size));
- return NULL;
- }
- static void
- xen_swiotlb_free_coherent(struct device *dev, size_t size, void *vaddr,
- dma_addr_t dma_handle, unsigned long attrs)
- {
- phys_addr_t phys = virt_to_phys(vaddr);
- int order = get_order(size);
- /* Convert the size to actually allocated. */
- size = 1UL << (order + XEN_PAGE_SHIFT);
- if (WARN_ON_ONCE(dma_handle + size - 1 > dev->coherent_dma_mask) ||
- WARN_ON_ONCE(range_straddles_page_boundary(phys, size)))
- return;
- if (TestClearPageXenRemapped(virt_to_page(vaddr)))
- xen_destroy_contiguous_region(phys, order);
- free_pages((unsigned long)vaddr, get_order(size));
- }
- #endif /* CONFIG_X86 */
- /*
- * Map a single buffer of the indicated size for DMA in streaming mode. The
- * physical address to use is returned.
- *
- * Once the device is given the dma address, the device owns this memory until
- * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
- */
- static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
- unsigned long offset, size_t size,
- enum dma_data_direction dir,
- unsigned long attrs)
- {
- phys_addr_t map, phys = page_to_phys(page) + offset;
- dma_addr_t dev_addr = xen_phys_to_dma(dev, phys);
- BUG_ON(dir == DMA_NONE);
- /*
- * If the address happens to be in the device's DMA window,
- * we can safely return the device addr and not worry about bounce
- * buffering it.
- */
- if (dma_capable(dev, dev_addr, size, true) &&
- !range_straddles_page_boundary(phys, size) &&
- !xen_arch_need_swiotlb(dev, phys, dev_addr) &&
- !is_swiotlb_force_bounce(dev))
- goto done;
- /*
- * Oh well, have to allocate and map a bounce buffer.
- */
- trace_swiotlb_bounced(dev, dev_addr, size);
- map = swiotlb_tbl_map_single(dev, phys, size, size, 0, dir, attrs);
- if (map == (phys_addr_t)DMA_MAPPING_ERROR)
- return DMA_MAPPING_ERROR;
- phys = map;
- dev_addr = xen_phys_to_dma(dev, map);
- /*
- * Ensure that the address returned is DMA'ble
- */
- if (unlikely(!dma_capable(dev, dev_addr, size, true))) {
- swiotlb_tbl_unmap_single(dev, map, size, dir,
- attrs | DMA_ATTR_SKIP_CPU_SYNC);
- return DMA_MAPPING_ERROR;
- }
- done:
- if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
- if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dev_addr))))
- arch_sync_dma_for_device(phys, size, dir);
- else
- xen_dma_sync_for_device(dev, dev_addr, size, dir);
- }
- return dev_addr;
- }
- /*
- * Unmap a single streaming mode DMA translation. The dma_addr and size must
- * match what was provided for in a previous xen_swiotlb_map_page call. All
- * other usages are undefined.
- *
- * After this call, reads by the cpu to the buffer are guaranteed to see
- * whatever the device wrote there.
- */
- static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
- size_t size, enum dma_data_direction dir, unsigned long attrs)
- {
- phys_addr_t paddr = xen_dma_to_phys(hwdev, dev_addr);
- BUG_ON(dir == DMA_NONE);
- if (!dev_is_dma_coherent(hwdev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
- if (pfn_valid(PFN_DOWN(dma_to_phys(hwdev, dev_addr))))
- arch_sync_dma_for_cpu(paddr, size, dir);
- else
- xen_dma_sync_for_cpu(hwdev, dev_addr, size, dir);
- }
- /* NOTE: We use dev_addr here, not paddr! */
- if (is_xen_swiotlb_buffer(hwdev, dev_addr))
- swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs);
- }
- static void
- xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,
- size_t size, enum dma_data_direction dir)
- {
- phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr);
- if (!dev_is_dma_coherent(dev)) {
- if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr))))
- arch_sync_dma_for_cpu(paddr, size, dir);
- else
- xen_dma_sync_for_cpu(dev, dma_addr, size, dir);
- }
- if (is_xen_swiotlb_buffer(dev, dma_addr))
- swiotlb_sync_single_for_cpu(dev, paddr, size, dir);
- }
- static void
- xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr,
- size_t size, enum dma_data_direction dir)
- {
- phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr);
- if (is_xen_swiotlb_buffer(dev, dma_addr))
- swiotlb_sync_single_for_device(dev, paddr, size, dir);
- if (!dev_is_dma_coherent(dev)) {
- if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr))))
- arch_sync_dma_for_device(paddr, size, dir);
- else
- xen_dma_sync_for_device(dev, dma_addr, size, dir);
- }
- }
- /*
- * Unmap a set of streaming mode DMA translations. Again, cpu read rules
- * concerning calls here are the same as for swiotlb_unmap_page() above.
- */
- static void
- xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
- enum dma_data_direction dir, unsigned long attrs)
- {
- struct scatterlist *sg;
- int i;
- BUG_ON(dir == DMA_NONE);
- for_each_sg(sgl, sg, nelems, i)
- xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg),
- dir, attrs);
- }
- static int
- xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems,
- enum dma_data_direction dir, unsigned long attrs)
- {
- struct scatterlist *sg;
- int i;
- BUG_ON(dir == DMA_NONE);
- for_each_sg(sgl, sg, nelems, i) {
- sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg),
- sg->offset, sg->length, dir, attrs);
- if (sg->dma_address == DMA_MAPPING_ERROR)
- goto out_unmap;
- sg_dma_len(sg) = sg->length;
- }
- return nelems;
- out_unmap:
- xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
- sg_dma_len(sgl) = 0;
- return -EIO;
- }
- static void
- xen_swiotlb_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl,
- int nelems, enum dma_data_direction dir)
- {
- struct scatterlist *sg;
- int i;
- for_each_sg(sgl, sg, nelems, i) {
- xen_swiotlb_sync_single_for_cpu(dev, sg->dma_address,
- sg->length, dir);
- }
- }
- static void
- xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
- int nelems, enum dma_data_direction dir)
- {
- struct scatterlist *sg;
- int i;
- for_each_sg(sgl, sg, nelems, i) {
- xen_swiotlb_sync_single_for_device(dev, sg->dma_address,
- sg->length, dir);
- }
- }
- /*
- * Return whether the given device DMA address mask can be supported
- * properly. For example, if your device can only drive the low 24-bits
- * during bus mastering, then you would pass 0x00ffffff as the mask to
- * this function.
- */
- static int
- xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
- {
- return xen_phys_to_dma(hwdev, io_tlb_default_mem.end - 1) <= mask;
- }
- const struct dma_map_ops xen_swiotlb_dma_ops = {
- #ifdef CONFIG_X86
- .alloc = xen_swiotlb_alloc_coherent,
- .free = xen_swiotlb_free_coherent,
- #else
- .alloc = dma_direct_alloc,
- .free = dma_direct_free,
- #endif
- .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,
- .unmap_sg = xen_swiotlb_unmap_sg,
- .map_page = xen_swiotlb_map_page,
- .unmap_page = xen_swiotlb_unmap_page,
- .dma_supported = xen_swiotlb_dma_supported,
- .mmap = dma_common_mmap,
- .get_sgtable = dma_common_get_sgtable,
- .alloc_pages = dma_common_alloc_pages,
- .free_pages = dma_common_free_pages,
- .max_mapping_size = swiotlb_max_mapping_size,
- };
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