diff options
Diffstat (limited to 'drivers/xen/swiotlb-xen.c')
| -rw-r--r-- | drivers/xen/swiotlb-xen.c | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c new file mode 100644 index 00000000000..54469c3eeac --- /dev/null +++ b/drivers/xen/swiotlb-xen.c @@ -0,0 +1,515 @@ +/* + * Copyright 2010 + * by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> + * + * This code provides a IOMMU for Xen PV guests with PCI passthrough. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License v2.0 as published by + * the Free Software Foundation + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * 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. + * + */ + +#include <linux/bootmem.h> +#include <linux/dma-mapping.h> +#include <xen/swiotlb-xen.h> +#include <xen/page.h> +#include <xen/xen-ops.h> +/* + * 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. + */ + +u64 start_dma_addr; + +static dma_addr_t xen_phys_to_bus(phys_addr_t paddr) +{ + return phys_to_machine(XPADDR(paddr)).maddr;; +} + +static phys_addr_t xen_bus_to_phys(dma_addr_t baddr) +{ + return machine_to_phys(XMADDR(baddr)).paddr; +} + +static dma_addr_t xen_virt_to_bus(void *address) +{ + return xen_phys_to_bus(virt_to_phys(address)); +} + +static int check_pages_physically_contiguous(unsigned long pfn, + unsigned int offset, + size_t length) +{ + unsigned long next_mfn; + int i; + int nr_pages; + + next_mfn = pfn_to_mfn(pfn); + nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT; + + for (i = 1; i < nr_pages; i++) { + if (pfn_to_mfn(++pfn) != ++next_mfn) + return 0; + } + return 1; +} + +static int range_straddles_page_boundary(phys_addr_t p, size_t size) +{ + unsigned long pfn = PFN_DOWN(p); + unsigned int offset = p & ~PAGE_MASK; + + if (offset + size <= PAGE_SIZE) + return 0; + if (check_pages_physically_contiguous(pfn, offset, size)) + return 0; + return 1; +} + +static int is_xen_swiotlb_buffer(dma_addr_t dma_addr) +{ + unsigned long mfn = PFN_DOWN(dma_addr); + unsigned long pfn = mfn_to_local_pfn(mfn); + phys_addr_t paddr; + + /* 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)) { + paddr = PFN_PHYS(pfn); + return paddr >= virt_to_phys(xen_io_tlb_start) && + paddr < virt_to_phys(xen_io_tlb_end); + } + return 0; +} + +static int max_dma_bits = 32; + +static int +xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) +{ + int i, rc; + int dma_bits; + + 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( + (unsigned long)buf + (i << IO_TLB_SHIFT), + get_order(slabs << IO_TLB_SHIFT), + dma_bits); + } while (rc && dma_bits++ < max_dma_bits); + if (rc) + return rc; + + i += slabs; + } while (i < nslabs); + return 0; +} + +void __init xen_swiotlb_init(int verbose) +{ + unsigned long bytes; + int rc; + + xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT); + xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE); + + bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT; + + /* + * Get IO TLB memory from any location. + */ + xen_io_tlb_start = alloc_bootmem(bytes); + if (!xen_io_tlb_start) + panic("Cannot allocate SWIOTLB buffer"); + + xen_io_tlb_end = xen_io_tlb_start + bytes; + /* + * And replace that memory with pages under 4GB. + */ + rc = xen_swiotlb_fixup(xen_io_tlb_start, + bytes, + xen_io_tlb_nslabs); + if (rc) + goto error; + + start_dma_addr = xen_virt_to_bus(xen_io_tlb_start); + swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose); + + return; +error: + panic("DMA(%d): Failed to exchange pages allocated for DMA with Xen! "\ + "We either don't have the permission or you do not have enough"\ + "free memory under 4GB!\n", rc); +} + +void * +xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, + dma_addr_t *dma_handle, gfp_t flags) +{ + void *ret; + int order = get_order(size); + u64 dma_mask = DMA_BIT_MASK(32); + unsigned long vstart; + + /* + * 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); + + if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret)) + return ret; + + vstart = __get_free_pages(flags, order); + ret = (void *)vstart; + + if (hwdev && hwdev->coherent_dma_mask) + dma_mask = dma_alloc_coherent_mask(hwdev, flags); + + if (ret) { + if (xen_create_contiguous_region(vstart, order, + fls64(dma_mask)) != 0) { + free_pages(vstart, order); + return NULL; + } + memset(ret, 0, size); + *dma_handle = virt_to_machine(ret).maddr; + } + return ret; +} +EXPORT_SYMBOL_GPL(xen_swiotlb_alloc_coherent); + +void +xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, + dma_addr_t dev_addr) +{ + int order = get_order(size); + + if (dma_release_from_coherent(hwdev, order, vaddr)) + return; + + xen_destroy_contiguous_region((unsigned long)vaddr, order); + free_pages((unsigned long)vaddr, order); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent); + + +/* + * 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. + */ +dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, + unsigned long offset, size_t size, + enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + phys_addr_t phys = page_to_phys(page) + offset; + dma_addr_t dev_addr = xen_phys_to_bus(phys); + void *map; + + 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) && + !range_straddles_page_boundary(phys, size) && !swiotlb_force) + return dev_addr; + + /* + * Oh well, have to allocate and map a bounce buffer. + */ + map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir); + if (!map) + return DMA_ERROR_CODE; + + dev_addr = xen_virt_to_bus(map); + + /* + * Ensure that the address returned is DMA'ble + */ + if (!dma_capable(dev, dev_addr, size)) + panic("map_single: bounce buffer is not DMA'ble"); + + return dev_addr; +} +EXPORT_SYMBOL_GPL(xen_swiotlb_map_page); + +/* + * 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_unmap_single(struct device *hwdev, dma_addr_t dev_addr, + size_t size, enum dma_data_direction dir) +{ + phys_addr_t paddr = xen_bus_to_phys(dev_addr); + + BUG_ON(dir == DMA_NONE); + + /* NOTE: We use dev_addr here, not paddr! */ + if (is_xen_swiotlb_buffer(dev_addr)) { + swiotlb_tbl_unmap_single(hwdev, phys_to_virt(paddr), size, dir); + return; + } + + if (dir != DMA_FROM_DEVICE) + return; + + /* + * phys_to_virt doesn't work with hihgmem page but we could + * call dma_mark_clean() with hihgmem page here. However, we + * are fine since dma_mark_clean() is null on POWERPC. We can + * make dma_mark_clean() take a physical address if necessary. + */ + dma_mark_clean(phys_to_virt(paddr), size); +} + +void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, + size_t size, enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + xen_unmap_single(hwdev, dev_addr, size, dir); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_page); + +/* + * Make physical memory consistent for a single streaming mode DMA translation + * after a transfer. + * + * If you perform a xen_swiotlb_map_page() but wish to interrogate the buffer + * using the cpu, yet do not wish to teardown the dma mapping, you must + * call this function before doing so. At the next point you give the dma + * address back to the card, you must first perform a + * xen_swiotlb_dma_sync_for_device, and then the device again owns the buffer + */ +static void +xen_swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr, + size_t size, enum dma_data_direction dir, + enum dma_sync_target target) +{ + phys_addr_t paddr = xen_bus_to_phys(dev_addr); + + BUG_ON(dir == DMA_NONE); + + /* NOTE: We use dev_addr here, not paddr! */ + if (is_xen_swiotlb_buffer(dev_addr)) { + swiotlb_tbl_sync_single(hwdev, phys_to_virt(paddr), size, dir, + target); + return; + } + + if (dir != DMA_FROM_DEVICE) + return; + + dma_mark_clean(phys_to_virt(paddr), size); +} + +void +xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr, + size_t size, enum dma_data_direction dir) +{ + xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_cpu); + +void +xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr, + size_t size, enum dma_data_direction dir) +{ + xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_device); + +/* + * Map a set of buffers described by scatterlist in streaming mode for DMA. + * This is the scatter-gather version of the above xen_swiotlb_map_page + * interface. Here the scatter gather list elements are each tagged with the + * appropriate dma address and length. They are obtained via + * sg_dma_{address,length}(SG). + * + * NOTE: An implementation may be able to use a smaller number of + * DMA address/length pairs than there are SG table elements. + * (for example via virtual mapping capabilities) + * The routine returns the number of addr/length pairs actually + * used, at most nents. + * + * Device ownership issues as mentioned above for xen_swiotlb_map_page are the + * same here. + */ +int +xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, + int nelems, enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + struct scatterlist *sg; + int i; + + BUG_ON(dir == DMA_NONE); + + for_each_sg(sgl, sg, nelems, i) { + phys_addr_t paddr = sg_phys(sg); + dma_addr_t dev_addr = xen_phys_to_bus(paddr); + + if (swiotlb_force || + !dma_capable(hwdev, dev_addr, sg->length) || + range_straddles_page_boundary(paddr, sg->length)) { + void *map = swiotlb_tbl_map_single(hwdev, + start_dma_addr, + sg_phys(sg), + sg->length, dir); + if (!map) { + /* Don't panic here, we expect map_sg users + to do proper error handling. */ + xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir, + attrs); + sgl[0].dma_length = 0; + return DMA_ERROR_CODE; + } + sg->dma_address = xen_virt_to_bus(map); + } else + sg->dma_address = dev_addr; + sg->dma_length = sg->length; + } + return nelems; +} +EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg_attrs); + +int +xen_swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, + enum dma_data_direction dir) +{ + return xen_swiotlb_map_sg_attrs(hwdev, sgl, nelems, dir, NULL); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg); + +/* + * Unmap a set of streaming mode DMA translations. Again, cpu read rules + * concerning calls here are the same as for swiotlb_unmap_page() above. + */ +void +xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl, + int nelems, enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + struct scatterlist *sg; + int i; + + BUG_ON(dir == DMA_NONE); + + for_each_sg(sgl, sg, nelems, i) + xen_unmap_single(hwdev, sg->dma_address, sg->dma_length, dir); + +} +EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg_attrs); + +void +xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, + enum dma_data_direction dir) +{ + return xen_swiotlb_unmap_sg_attrs(hwdev, sgl, nelems, dir, NULL); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg); + +/* + * Make physical memory consistent for a set of streaming mode DMA translations + * after a transfer. + * + * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules + * and usage. + */ +static void +xen_swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl, + int nelems, enum dma_data_direction dir, + enum dma_sync_target target) +{ + struct scatterlist *sg; + int i; + + for_each_sg(sgl, sg, nelems, i) + xen_swiotlb_sync_single(hwdev, sg->dma_address, + sg->dma_length, dir, target); +} + +void +xen_swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg, + int nelems, enum dma_data_direction dir) +{ + xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_cpu); + +void +xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg, + int nelems, enum dma_data_direction dir) +{ + xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE); +} +EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device); + +int +xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr) +{ + return !dma_addr; +} +EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mapping_error); + +/* + * 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. + */ +int +xen_swiotlb_dma_supported(struct device *hwdev, u64 mask) +{ + return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask; +} +EXPORT_SYMBOL_GPL(xen_swiotlb_dma_supported); |