diff options
Diffstat (limited to 'drivers/xen/swiotlb-xen.c')
| -rw-r--r-- | drivers/xen/swiotlb-xen.c | 583 |
1 files changed, 583 insertions, 0 deletions
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c new file mode 100644 index 000000000..ad3ee4857 --- /dev/null +++ b/drivers/xen/swiotlb-xen.c @@ -0,0 +1,583 @@ +// 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 <asm/xen/page-coherent.h> + +#include <trace/events/swiotlb.h> +#define MAX_DMA_BITS 32 +/* + * Used to do a quick range check in swiotlb_tbl_unmap_single and + * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this + * API. + */ + +static char *xen_io_tlb_start, *xen_io_tlb_end; +static unsigned long xen_io_tlb_nslabs; +/* + * 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 dma_addr_t xen_virt_to_bus(struct device *dev, void *address) +{ + return xen_phys_to_dma(dev, virt_to_phys(address)); +} + +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 paddr >= virt_to_phys(xen_io_tlb_start) && + paddr < virt_to_phys(xen_io_tlb_end); + } + return 0; +} + +static int +xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) +{ + int i, rc; + int dma_bits; + dma_addr_t dma_handle; + phys_addr_t p = virt_to_phys(buf); + + dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT; + + i = 0; + do { + int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE); + + do { + rc = xen_create_contiguous_region( + p + (i << IO_TLB_SHIFT), + get_order(slabs << IO_TLB_SHIFT), + dma_bits, &dma_handle); + } while (rc && dma_bits++ < MAX_DMA_BITS); + if (rc) + return rc; + + i += slabs; + } while (i < nslabs); + return 0; +} +static unsigned long xen_set_nslabs(unsigned long nr_tbl) +{ + if (!nr_tbl) { + xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT); + xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE); + } else + xen_io_tlb_nslabs = nr_tbl; + + return xen_io_tlb_nslabs << IO_TLB_SHIFT; +} + +enum xen_swiotlb_err { + XEN_SWIOTLB_UNKNOWN = 0, + XEN_SWIOTLB_ENOMEM, + XEN_SWIOTLB_EFIXUP +}; + +static const char *xen_swiotlb_error(enum xen_swiotlb_err err) +{ + switch (err) { + case XEN_SWIOTLB_ENOMEM: + return "Cannot allocate Xen-SWIOTLB buffer\n"; + case XEN_SWIOTLB_EFIXUP: + return "Failed to get contiguous memory for DMA from Xen!\n"\ + "You either: don't have the permissions, do not have"\ + " enough free memory under 4GB, or the hypervisor memory"\ + " is too fragmented!"; + default: + break; + } + return ""; +} +int __ref xen_swiotlb_init(int verbose, bool early) +{ + unsigned long bytes, order; + int rc = -ENOMEM; + enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN; + unsigned int repeat = 3; + + xen_io_tlb_nslabs = swiotlb_nr_tbl(); +retry: + bytes = xen_set_nslabs(xen_io_tlb_nslabs); + order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT); + + /* + * IO TLB memory already allocated. Just use it. + */ + if (io_tlb_start != 0) { + xen_io_tlb_start = phys_to_virt(io_tlb_start); + goto end; + } + + /* + * Get IO TLB memory from any location. + */ + if (early) { + xen_io_tlb_start = memblock_alloc(PAGE_ALIGN(bytes), + PAGE_SIZE); + if (!xen_io_tlb_start) + panic("%s: Failed to allocate %lu bytes align=0x%lx\n", + __func__, PAGE_ALIGN(bytes), PAGE_SIZE); + } else { +#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT)) +#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT) + while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) { + xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order); + if (xen_io_tlb_start) + break; + order--; + } + if (order != get_order(bytes)) { + pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n", + (PAGE_SIZE << order) >> 20); + xen_io_tlb_nslabs = SLABS_PER_PAGE << order; + bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT; + } + } + if (!xen_io_tlb_start) { + m_ret = XEN_SWIOTLB_ENOMEM; + goto error; + } + /* + * And replace that memory with pages under 4GB. + */ + rc = xen_swiotlb_fixup(xen_io_tlb_start, + bytes, + xen_io_tlb_nslabs); + if (rc) { + if (early) + memblock_free(__pa(xen_io_tlb_start), + PAGE_ALIGN(bytes)); + else { + free_pages((unsigned long)xen_io_tlb_start, order); + xen_io_tlb_start = NULL; + } + m_ret = XEN_SWIOTLB_EFIXUP; + goto error; + } + if (early) { + if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, + verbose)) + panic("Cannot allocate SWIOTLB buffer"); + rc = 0; + } else + rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs); + +end: + xen_io_tlb_end = xen_io_tlb_start + bytes; + if (!rc) + swiotlb_set_max_segment(PAGE_SIZE); + + return rc; +error: + if (repeat--) { + xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */ + (xen_io_tlb_nslabs >> 1)); + pr_info("Lowering to %luMB\n", + (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20); + goto retry; + } + pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc); + if (early) + panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc); + else + free_pages((unsigned long)xen_io_tlb_start, order); + return rc; +} + +static void * +xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, + dma_addr_t *dma_handle, gfp_t flags, + unsigned long attrs) +{ + void *ret; + int order = get_order(size); + u64 dma_mask = DMA_BIT_MASK(32); + phys_addr_t phys; + dma_addr_t dev_addr; + + /* + * Ignore region specifiers - the kernel's ideas of + * pseudo-phys memory layout has nothing to do with the + * machine physical layout. We can't allocate highmem + * because we can't return a pointer to it. + */ + flags &= ~(__GFP_DMA | __GFP_HIGHMEM); + + /* Convert the size to actually allocated. */ + size = 1UL << (order + XEN_PAGE_SHIFT); + + /* On ARM this function returns an ioremap'ped virtual address for + * which virt_to_phys doesn't return the corresponding physical + * address. In fact on ARM virt_to_phys only works for kernel direct + * mapped RAM memory. Also see comment below. + */ + ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs); + + if (!ret) + return ret; + + if (hwdev && hwdev->coherent_dma_mask) + dma_mask = hwdev->coherent_dma_mask; + + /* At this point dma_handle is the dma address, next we are + * going to set it to the machine address. + * Do not use virt_to_phys(ret) because on ARM it doesn't correspond + * to *dma_handle. */ + phys = dma_to_phys(hwdev, *dma_handle); + dev_addr = xen_phys_to_dma(hwdev, phys); + if (((dev_addr + size - 1 <= dma_mask)) && + !range_straddles_page_boundary(phys, size)) + *dma_handle = dev_addr; + else { + if (xen_create_contiguous_region(phys, order, + fls64(dma_mask), dma_handle) != 0) { + xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs); + return NULL; + } + *dma_handle = phys_to_dma(hwdev, *dma_handle); + SetPageXenRemapped(virt_to_page(ret)); + } + memset(ret, 0, size); + return ret; +} + +static void +xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, + dma_addr_t dev_addr, unsigned long attrs) +{ + int order = get_order(size); + phys_addr_t phys; + u64 dma_mask = DMA_BIT_MASK(32); + struct page *page; + + if (hwdev && hwdev->coherent_dma_mask) + dma_mask = hwdev->coherent_dma_mask; + + /* do not use virt_to_phys because on ARM it doesn't return you the + * physical address */ + phys = xen_dma_to_phys(hwdev, dev_addr); + + /* Convert the size to actually allocated. */ + size = 1UL << (order + XEN_PAGE_SHIFT); + + if (is_vmalloc_addr(vaddr)) + page = vmalloc_to_page(vaddr); + else + page = virt_to_page(vaddr); + + if (!WARN_ON((dev_addr + size - 1 > dma_mask) || + range_straddles_page_boundary(phys, size)) && + TestClearPageXenRemapped(page)) + xen_destroy_contiguous_region(phys, order); + + xen_free_coherent_pages(hwdev, size, vaddr, phys_to_dma(hwdev, phys), + attrs); +} + +/* + * 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) && + swiotlb_force != SWIOTLB_FORCE) + goto done; + + /* + * Oh well, have to allocate and map a bounce buffer. + */ + trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); + + map = swiotlb_tbl_map_single(dev, phys, size, size, 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, 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, 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_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_CPU); +} + +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_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_DEVICE); + + 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 0; +} + +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_virt_to_bus(hwdev, xen_io_tlb_end - 1) <= mask; +} + +const struct dma_map_ops xen_swiotlb_dma_ops = { + .alloc = xen_swiotlb_alloc_coherent, + .free = xen_swiotlb_free_coherent, + .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, +}; |