diff options
Diffstat (limited to 'drivers/xen/swiotlb-xen.c')
| -rw-r--r-- | drivers/xen/swiotlb-xen.c | 688 |
1 files changed, 688 insertions, 0 deletions
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c new file mode 100644 index 000000000..4c549323c --- /dev/null +++ b/drivers/xen/swiotlb-xen.c @@ -0,0 +1,688 @@ +/* + * 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. + * + */ + +#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt + +#include <linux/bootmem.h> +#include <linux/dma-mapping.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> +/* + * 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. + */ + +#ifndef CONFIG_X86 +static unsigned long dma_alloc_coherent_mask(struct device *dev, + gfp_t gfp) +{ + unsigned long dma_mask = 0; + + dma_mask = dev->coherent_dma_mask; + if (!dma_mask) + dma_mask = (gfp & GFP_DMA) ? DMA_BIT_MASK(24) : DMA_BIT_MASK(32); + + return dma_mask; +} +#endif + +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 u64 start_dma_addr; + +/* + * Both of these functions should avoid PFN_PHYS because phys_addr_t + * can be 32bit when dma_addr_t is 64bit leading to a loss in + * information if the shift is done before casting to 64bit. + */ +static inline dma_addr_t xen_phys_to_bus(phys_addr_t paddr) +{ + unsigned long mfn = pfn_to_mfn(PFN_DOWN(paddr)); + dma_addr_t dma = (dma_addr_t)mfn << PAGE_SHIFT; + + dma |= paddr & ~PAGE_MASK; + + return dma; +} + +static inline phys_addr_t xen_bus_to_phys(dma_addr_t baddr) +{ + unsigned long pfn = mfn_to_pfn(PFN_DOWN(baddr)); + dma_addr_t dma = (dma_addr_t)pfn << PAGE_SHIFT; + phys_addr_t paddr = dma; + + paddr |= baddr & ~PAGE_MASK; + + return paddr; +} + +static inline 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 inline 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_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); + /* + * Get IO TLB memory from any location. + */ + if (early) + xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes)); + 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; + } + 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) { + if (early) + free_bootmem(__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; + } + start_dma_addr = xen_virt_to_bus(xen_io_tlb_start); + 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); + 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; +} +void * +xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, + dma_addr_t *dma_handle, gfp_t flags, + struct dma_attrs *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); + + if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret)) + return ret; + + /* 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 = dma_alloc_coherent_mask(hwdev, flags); + + /* At this point dma_handle is the physical 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_handle; + dev_addr = xen_phys_to_bus(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; + } + } + memset(ret, 0, size); + 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, struct dma_attrs *attrs) +{ + int order = get_order(size); + phys_addr_t phys; + u64 dma_mask = DMA_BIT_MASK(32); + + if (dma_release_from_coherent(hwdev, order, vaddr)) + return; + + 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_bus_to_phys(dev_addr); + + if (((dev_addr + size - 1 > dma_mask)) || + range_straddles_page_boundary(phys, size)) + xen_destroy_contiguous_region(phys, order); + + xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs); +} +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 map, phys = page_to_phys(page) + offset; + dma_addr_t dev_addr = xen_phys_to_bus(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) && + !range_straddles_page_boundary(phys, size) && + !xen_arch_need_swiotlb(dev, PFN_DOWN(phys), PFN_DOWN(dev_addr)) && + !swiotlb_force) { + /* we are not interested in the dma_addr returned by + * xen_dma_map_page, only in the potential cache flushes executed + * by the function. */ + xen_dma_map_page(dev, page, dev_addr, offset, size, dir, attrs); + return dev_addr; + } + + /* + * 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, start_dma_addr, phys, size, dir); + if (map == SWIOTLB_MAP_ERROR) + return DMA_ERROR_CODE; + + xen_dma_map_page(dev, pfn_to_page(map >> PAGE_SHIFT), + dev_addr, map & ~PAGE_MASK, size, dir, attrs); + dev_addr = xen_phys_to_bus(map); + + /* + * Ensure that the address returned is DMA'ble + */ + if (!dma_capable(dev, dev_addr, size)) { + swiotlb_tbl_unmap_single(dev, map, size, dir); + dev_addr = 0; + } + 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, + struct dma_attrs *attrs) +{ + phys_addr_t paddr = xen_bus_to_phys(dev_addr); + + BUG_ON(dir == DMA_NONE); + + xen_dma_unmap_page(hwdev, dev_addr, size, dir, attrs); + + /* NOTE: We use dev_addr here, not paddr! */ + if (is_xen_swiotlb_buffer(dev_addr)) { + swiotlb_tbl_unmap_single(hwdev, 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, attrs); +} +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); + + if (target == SYNC_FOR_CPU) + xen_dma_sync_single_for_cpu(hwdev, dev_addr, size, dir); + + /* NOTE: We use dev_addr here, not paddr! */ + if (is_xen_swiotlb_buffer(dev_addr)) + swiotlb_tbl_sync_single(hwdev, paddr, size, dir, target); + + if (target == SYNC_FOR_DEVICE) + xen_dma_sync_single_for_device(hwdev, dev_addr, size, dir); + + 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 || + xen_arch_need_swiotlb(hwdev, PFN_DOWN(paddr), PFN_DOWN(dev_addr)) || + !dma_capable(hwdev, dev_addr, sg->length) || + range_straddles_page_boundary(paddr, sg->length)) { + phys_addr_t map = swiotlb_tbl_map_single(hwdev, + start_dma_addr, + sg_phys(sg), + sg->length, + dir); + if (map == SWIOTLB_MAP_ERROR) { + dev_warn(hwdev, "swiotlb buffer is full\n"); + /* Don't panic here, we expect map_sg users + to do proper error handling. */ + xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir, + attrs); + sg_dma_len(sgl) = 0; + return 0; + } + xen_dma_map_page(hwdev, pfn_to_page(map >> PAGE_SHIFT), + dev_addr, + map & ~PAGE_MASK, + sg->length, + dir, + attrs); + sg->dma_address = xen_phys_to_bus(map); + } else { + /* we are not interested in the dma_addr returned by + * xen_dma_map_page, only in the potential cache flushes executed + * by the function. */ + xen_dma_map_page(hwdev, pfn_to_page(paddr >> PAGE_SHIFT), + dev_addr, + paddr & ~PAGE_MASK, + sg->length, + dir, + attrs); + sg->dma_address = dev_addr; + } + sg_dma_len(sg) = sg->length; + } + return nelems; +} +EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg_attrs); + +/* + * 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_len(sg), dir, attrs); + +} +EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg_attrs); + +/* + * 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_len(sg), 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); + +int +xen_swiotlb_set_dma_mask(struct device *dev, u64 dma_mask) +{ + if (!dev->dma_mask || !xen_swiotlb_dma_supported(dev, dma_mask)) + return -EIO; + + *dev->dma_mask = dma_mask; + + return 0; +} +EXPORT_SYMBOL_GPL(xen_swiotlb_set_dma_mask); |