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Diffstat (limited to 'drivers/xen/swiotlb-xen.c')
| -rw-r--r-- | drivers/xen/swiotlb-xen.c | 409 |
1 files changed, 409 insertions, 0 deletions
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c new file mode 100644 index 000000000..7290f2b40 --- /dev/null +++ b/drivers/xen/swiotlb-xen.c @@ -0,0 +1,409 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2010 + * by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> + * + * 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, +}; |