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567 lines
16 KiB
567 lines
16 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright 2010 |
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* by Konrad Rzeszutek Wilk <[email protected]> |
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* |
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* This code provides a IOMMU for Xen PV guests with PCI passthrough. |
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* |
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* PV guests under Xen are running in an non-contiguous memory architecture. |
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* |
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* When PCI pass-through is utilized, this necessitates an IOMMU for |
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* translating bus (DMA) to virtual and vice-versa and also providing a |
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* mechanism to have contiguous pages for device drivers operations (say DMA |
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* operations). |
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* |
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* Specifically, under Xen the Linux idea of pages is an illusion. It |
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* assumes that pages start at zero and go up to the available memory. To |
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* help with that, the Linux Xen MMU provides a lookup mechanism to |
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* translate the page frame numbers (PFN) to machine frame numbers (MFN) |
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* and vice-versa. The MFN are the "real" frame numbers. Furthermore |
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* memory is not contiguous. Xen hypervisor stitches memory for guests |
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* from different pools, which means there is no guarantee that PFN==MFN |
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* and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are |
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* allocated in descending order (high to low), meaning the guest might |
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* never get any MFN's under the 4GB mark. |
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*/ |
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#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt |
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|
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#include <linux/memblock.h> |
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#include <linux/dma-direct.h> |
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#include <linux/dma-map-ops.h> |
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#include <linux/export.h> |
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#include <xen/swiotlb-xen.h> |
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#include <xen/page.h> |
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#include <xen/xen-ops.h> |
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#include <xen/hvc-console.h> |
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|
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#include <asm/dma-mapping.h> |
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#include <asm/xen/page-coherent.h> |
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|
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#include <trace/events/swiotlb.h> |
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#define MAX_DMA_BITS 32 |
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|
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/* |
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* Quick lookup value of the bus address of the IOTLB. |
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*/ |
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|
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static inline phys_addr_t xen_phys_to_bus(struct device *dev, phys_addr_t paddr) |
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{ |
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unsigned long bfn = pfn_to_bfn(XEN_PFN_DOWN(paddr)); |
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phys_addr_t baddr = (phys_addr_t)bfn << XEN_PAGE_SHIFT; |
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baddr |= paddr & ~XEN_PAGE_MASK; |
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return baddr; |
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} |
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|
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static inline dma_addr_t xen_phys_to_dma(struct device *dev, phys_addr_t paddr) |
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{ |
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return phys_to_dma(dev, xen_phys_to_bus(dev, paddr)); |
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} |
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|
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static inline phys_addr_t xen_bus_to_phys(struct device *dev, |
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phys_addr_t baddr) |
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{ |
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unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr)); |
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phys_addr_t paddr = (xen_pfn << XEN_PAGE_SHIFT) | |
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(baddr & ~XEN_PAGE_MASK); |
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return paddr; |
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} |
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static inline phys_addr_t xen_dma_to_phys(struct device *dev, |
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dma_addr_t dma_addr) |
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{ |
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return xen_bus_to_phys(dev, dma_to_phys(dev, dma_addr)); |
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} |
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static inline int range_straddles_page_boundary(phys_addr_t p, size_t size) |
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{ |
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unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p); |
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unsigned int i, nr_pages = XEN_PFN_UP(xen_offset_in_page(p) + size); |
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next_bfn = pfn_to_bfn(xen_pfn); |
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for (i = 1; i < nr_pages; i++) |
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if (pfn_to_bfn(++xen_pfn) != ++next_bfn) |
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return 1; |
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return 0; |
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} |
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static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr) |
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{ |
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unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr)); |
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unsigned long xen_pfn = bfn_to_local_pfn(bfn); |
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phys_addr_t paddr = (phys_addr_t)xen_pfn << XEN_PAGE_SHIFT; |
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|
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/* If the address is outside our domain, it CAN |
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* have the same virtual address as another address |
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* in our domain. Therefore _only_ check address within our domain. |
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*/ |
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if (pfn_valid(PFN_DOWN(paddr))) |
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return is_swiotlb_buffer(dev, paddr); |
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return 0; |
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} |
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|
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static int xen_swiotlb_fixup(void *buf, unsigned long nslabs) |
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{ |
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int rc; |
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unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT); |
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unsigned int i, dma_bits = order + PAGE_SHIFT; |
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dma_addr_t dma_handle; |
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phys_addr_t p = virt_to_phys(buf); |
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|
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BUILD_BUG_ON(IO_TLB_SEGSIZE & (IO_TLB_SEGSIZE - 1)); |
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BUG_ON(nslabs % IO_TLB_SEGSIZE); |
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i = 0; |
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do { |
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do { |
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rc = xen_create_contiguous_region( |
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p + (i << IO_TLB_SHIFT), order, |
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dma_bits, &dma_handle); |
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} while (rc && dma_bits++ < MAX_DMA_BITS); |
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if (rc) |
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return rc; |
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i += IO_TLB_SEGSIZE; |
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} while (i < nslabs); |
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return 0; |
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} |
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enum xen_swiotlb_err { |
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XEN_SWIOTLB_UNKNOWN = 0, |
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XEN_SWIOTLB_ENOMEM, |
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XEN_SWIOTLB_EFIXUP |
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}; |
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static const char *xen_swiotlb_error(enum xen_swiotlb_err err) |
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{ |
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switch (err) { |
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case XEN_SWIOTLB_ENOMEM: |
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return "Cannot allocate Xen-SWIOTLB buffer\n"; |
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case XEN_SWIOTLB_EFIXUP: |
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return "Failed to get contiguous memory for DMA from Xen!\n"\ |
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"You either: don't have the permissions, do not have"\ |
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" enough free memory under 4GB, or the hypervisor memory"\ |
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" is too fragmented!"; |
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default: |
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break; |
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} |
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return ""; |
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} |
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int xen_swiotlb_init(void) |
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{ |
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enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN; |
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unsigned long bytes = swiotlb_size_or_default(); |
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unsigned long nslabs = bytes >> IO_TLB_SHIFT; |
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unsigned int order, repeat = 3; |
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int rc = -ENOMEM; |
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char *start; |
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if (io_tlb_default_mem.nslabs) { |
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pr_warn("swiotlb buffer already initialized\n"); |
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return -EEXIST; |
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} |
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retry: |
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m_ret = XEN_SWIOTLB_ENOMEM; |
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order = get_order(bytes); |
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|
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/* |
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* Get IO TLB memory from any location. |
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*/ |
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#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT)) |
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#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT) |
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while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) { |
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start = (void *)xen_get_swiotlb_free_pages(order); |
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if (start) |
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break; |
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order--; |
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} |
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if (!start) |
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goto exit; |
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if (order != get_order(bytes)) { |
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pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n", |
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(PAGE_SIZE << order) >> 20); |
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nslabs = SLABS_PER_PAGE << order; |
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bytes = nslabs << IO_TLB_SHIFT; |
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} |
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/* |
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* And replace that memory with pages under 4GB. |
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*/ |
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rc = xen_swiotlb_fixup(start, nslabs); |
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if (rc) { |
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free_pages((unsigned long)start, order); |
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m_ret = XEN_SWIOTLB_EFIXUP; |
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goto error; |
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} |
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rc = swiotlb_late_init_with_tbl(start, nslabs); |
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if (rc) |
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return rc; |
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swiotlb_set_max_segment(PAGE_SIZE); |
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return 0; |
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error: |
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if (nslabs > 1024 && repeat--) { |
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/* Min is 2MB */ |
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nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE)); |
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bytes = nslabs << IO_TLB_SHIFT; |
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pr_info("Lowering to %luMB\n", bytes >> 20); |
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goto retry; |
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} |
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exit: |
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pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc); |
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return rc; |
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} |
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#ifdef CONFIG_X86 |
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void __init xen_swiotlb_init_early(void) |
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{ |
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unsigned long bytes = swiotlb_size_or_default(); |
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unsigned long nslabs = bytes >> IO_TLB_SHIFT; |
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unsigned int repeat = 3; |
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char *start; |
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int rc; |
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retry: |
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/* |
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* Get IO TLB memory from any location. |
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*/ |
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start = memblock_alloc(PAGE_ALIGN(bytes), |
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IO_TLB_SEGSIZE << IO_TLB_SHIFT); |
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if (!start) |
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panic("%s: Failed to allocate %lu bytes\n", |
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__func__, PAGE_ALIGN(bytes)); |
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/* |
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* And replace that memory with pages under 4GB. |
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*/ |
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rc = xen_swiotlb_fixup(start, nslabs); |
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if (rc) { |
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memblock_free(__pa(start), PAGE_ALIGN(bytes)); |
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if (nslabs > 1024 && repeat--) { |
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/* Min is 2MB */ |
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nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE)); |
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bytes = nslabs << IO_TLB_SHIFT; |
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pr_info("Lowering to %luMB\n", bytes >> 20); |
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goto retry; |
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} |
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panic("%s (rc:%d)", xen_swiotlb_error(XEN_SWIOTLB_EFIXUP), rc); |
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} |
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if (swiotlb_init_with_tbl(start, nslabs, true)) |
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panic("Cannot allocate SWIOTLB buffer"); |
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swiotlb_set_max_segment(PAGE_SIZE); |
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} |
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#endif /* CONFIG_X86 */ |
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static void * |
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xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, |
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dma_addr_t *dma_handle, gfp_t flags, |
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unsigned long attrs) |
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{ |
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void *ret; |
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int order = get_order(size); |
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u64 dma_mask = DMA_BIT_MASK(32); |
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phys_addr_t phys; |
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dma_addr_t dev_addr; |
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/* |
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* Ignore region specifiers - the kernel's ideas of |
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* pseudo-phys memory layout has nothing to do with the |
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* machine physical layout. We can't allocate highmem |
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* because we can't return a pointer to it. |
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*/ |
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flags &= ~(__GFP_DMA | __GFP_HIGHMEM); |
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/* Convert the size to actually allocated. */ |
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size = 1UL << (order + XEN_PAGE_SHIFT); |
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|
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/* On ARM this function returns an ioremap'ped virtual address for |
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* which virt_to_phys doesn't return the corresponding physical |
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* address. In fact on ARM virt_to_phys only works for kernel direct |
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* mapped RAM memory. Also see comment below. |
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*/ |
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ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs); |
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if (!ret) |
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return ret; |
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if (hwdev && hwdev->coherent_dma_mask) |
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dma_mask = hwdev->coherent_dma_mask; |
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|
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/* At this point dma_handle is the dma address, next we are |
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* going to set it to the machine address. |
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* Do not use virt_to_phys(ret) because on ARM it doesn't correspond |
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* to *dma_handle. */ |
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phys = dma_to_phys(hwdev, *dma_handle); |
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dev_addr = xen_phys_to_dma(hwdev, phys); |
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if (((dev_addr + size - 1 <= dma_mask)) && |
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!range_straddles_page_boundary(phys, size)) |
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*dma_handle = dev_addr; |
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else { |
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if (xen_create_contiguous_region(phys, order, |
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fls64(dma_mask), dma_handle) != 0) { |
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xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs); |
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return NULL; |
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} |
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*dma_handle = phys_to_dma(hwdev, *dma_handle); |
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SetPageXenRemapped(virt_to_page(ret)); |
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} |
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memset(ret, 0, size); |
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return ret; |
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} |
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static void |
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xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, |
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dma_addr_t dev_addr, unsigned long attrs) |
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{ |
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int order = get_order(size); |
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phys_addr_t phys; |
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u64 dma_mask = DMA_BIT_MASK(32); |
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struct page *page; |
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if (hwdev && hwdev->coherent_dma_mask) |
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dma_mask = hwdev->coherent_dma_mask; |
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|
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/* do not use virt_to_phys because on ARM it doesn't return you the |
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* physical address */ |
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phys = xen_dma_to_phys(hwdev, dev_addr); |
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|
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/* Convert the size to actually allocated. */ |
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size = 1UL << (order + XEN_PAGE_SHIFT); |
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if (is_vmalloc_addr(vaddr)) |
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page = vmalloc_to_page(vaddr); |
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else |
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page = virt_to_page(vaddr); |
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if (!WARN_ON((dev_addr + size - 1 > dma_mask) || |
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range_straddles_page_boundary(phys, size)) && |
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TestClearPageXenRemapped(page)) |
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xen_destroy_contiguous_region(phys, order); |
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xen_free_coherent_pages(hwdev, size, vaddr, phys_to_dma(hwdev, phys), |
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attrs); |
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} |
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|
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/* |
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* Map a single buffer of the indicated size for DMA in streaming mode. The |
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* physical address to use is returned. |
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* |
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* Once the device is given the dma address, the device owns this memory until |
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* either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed. |
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*/ |
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static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, |
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unsigned long offset, size_t size, |
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enum dma_data_direction dir, |
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unsigned long attrs) |
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{ |
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phys_addr_t map, phys = page_to_phys(page) + offset; |
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dma_addr_t dev_addr = xen_phys_to_dma(dev, phys); |
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|
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BUG_ON(dir == DMA_NONE); |
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/* |
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* If the address happens to be in the device's DMA window, |
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* we can safely return the device addr and not worry about bounce |
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* buffering it. |
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*/ |
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if (dma_capable(dev, dev_addr, size, true) && |
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!range_straddles_page_boundary(phys, size) && |
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!xen_arch_need_swiotlb(dev, phys, dev_addr) && |
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!is_swiotlb_force_bounce(dev)) |
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goto done; |
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|
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/* |
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* Oh well, have to allocate and map a bounce buffer. |
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*/ |
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trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); |
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map = swiotlb_tbl_map_single(dev, phys, size, size, dir, attrs); |
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if (map == (phys_addr_t)DMA_MAPPING_ERROR) |
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return DMA_MAPPING_ERROR; |
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phys = map; |
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dev_addr = xen_phys_to_dma(dev, map); |
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/* |
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* Ensure that the address returned is DMA'ble |
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*/ |
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if (unlikely(!dma_capable(dev, dev_addr, size, true))) { |
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swiotlb_tbl_unmap_single(dev, map, size, dir, |
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attrs | DMA_ATTR_SKIP_CPU_SYNC); |
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return DMA_MAPPING_ERROR; |
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} |
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done: |
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if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { |
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if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dev_addr)))) |
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arch_sync_dma_for_device(phys, size, dir); |
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else |
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xen_dma_sync_for_device(dev, dev_addr, size, dir); |
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} |
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return dev_addr; |
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} |
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/* |
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* Unmap a single streaming mode DMA translation. The dma_addr and size must |
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* match what was provided for in a previous xen_swiotlb_map_page call. All |
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* other usages are undefined. |
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* |
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* After this call, reads by the cpu to the buffer are guaranteed to see |
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* whatever the device wrote there. |
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*/ |
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static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, |
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size_t size, enum dma_data_direction dir, unsigned long attrs) |
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{ |
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phys_addr_t paddr = xen_dma_to_phys(hwdev, dev_addr); |
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BUG_ON(dir == DMA_NONE); |
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if (!dev_is_dma_coherent(hwdev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { |
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if (pfn_valid(PFN_DOWN(dma_to_phys(hwdev, dev_addr)))) |
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arch_sync_dma_for_cpu(paddr, size, dir); |
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else |
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xen_dma_sync_for_cpu(hwdev, dev_addr, size, dir); |
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} |
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|
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/* NOTE: We use dev_addr here, not paddr! */ |
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if (is_xen_swiotlb_buffer(hwdev, dev_addr)) |
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swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs); |
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} |
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|
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static void |
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xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, |
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size_t size, enum dma_data_direction dir) |
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{ |
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phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr); |
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|
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if (!dev_is_dma_coherent(dev)) { |
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if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr)))) |
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arch_sync_dma_for_cpu(paddr, size, dir); |
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else |
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xen_dma_sync_for_cpu(dev, dma_addr, size, dir); |
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} |
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|
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if (is_xen_swiotlb_buffer(dev, dma_addr)) |
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swiotlb_sync_single_for_cpu(dev, paddr, size, dir); |
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} |
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|
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static void |
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xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, |
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size_t size, enum dma_data_direction dir) |
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{ |
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phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr); |
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|
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if (is_xen_swiotlb_buffer(dev, dma_addr)) |
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swiotlb_sync_single_for_device(dev, paddr, size, dir); |
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|
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if (!dev_is_dma_coherent(dev)) { |
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if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr)))) |
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arch_sync_dma_for_device(paddr, size, dir); |
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else |
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xen_dma_sync_for_device(dev, dma_addr, size, dir); |
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} |
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} |
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|
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/* |
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* Unmap a set of streaming mode DMA translations. Again, cpu read rules |
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* concerning calls here are the same as for swiotlb_unmap_page() above. |
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*/ |
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static void |
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xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, |
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enum dma_data_direction dir, unsigned long attrs) |
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{ |
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struct scatterlist *sg; |
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int i; |
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|
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BUG_ON(dir == DMA_NONE); |
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|
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for_each_sg(sgl, sg, nelems, i) |
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xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg), |
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dir, attrs); |
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|
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} |
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|
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static int |
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xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems, |
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enum dma_data_direction dir, unsigned long attrs) |
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{ |
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struct scatterlist *sg; |
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int i; |
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|
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BUG_ON(dir == DMA_NONE); |
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|
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for_each_sg(sgl, sg, nelems, i) { |
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sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg), |
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sg->offset, sg->length, dir, attrs); |
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if (sg->dma_address == DMA_MAPPING_ERROR) |
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goto out_unmap; |
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sg_dma_len(sg) = sg->length; |
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} |
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|
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return nelems; |
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out_unmap: |
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xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); |
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sg_dma_len(sgl) = 0; |
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return -EIO; |
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} |
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|
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static void |
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xen_swiotlb_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl, |
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int nelems, enum dma_data_direction dir) |
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{ |
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struct scatterlist *sg; |
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int i; |
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|
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for_each_sg(sgl, sg, nelems, i) { |
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xen_swiotlb_sync_single_for_cpu(dev, sg->dma_address, |
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sg->length, dir); |
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} |
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} |
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|
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static void |
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xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl, |
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int nelems, enum dma_data_direction dir) |
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{ |
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struct scatterlist *sg; |
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int i; |
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for_each_sg(sgl, sg, nelems, i) { |
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xen_swiotlb_sync_single_for_device(dev, sg->dma_address, |
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sg->length, dir); |
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} |
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} |
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/* |
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* Return whether the given device DMA address mask can be supported |
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* properly. For example, if your device can only drive the low 24-bits |
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* during bus mastering, then you would pass 0x00ffffff as the mask to |
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* this function. |
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*/ |
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static int |
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xen_swiotlb_dma_supported(struct device *hwdev, u64 mask) |
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{ |
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return xen_phys_to_dma(hwdev, io_tlb_default_mem.end - 1) <= mask; |
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} |
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const struct dma_map_ops xen_swiotlb_dma_ops = { |
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.alloc = xen_swiotlb_alloc_coherent, |
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.free = xen_swiotlb_free_coherent, |
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.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu, |
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.sync_single_for_device = xen_swiotlb_sync_single_for_device, |
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.sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu, |
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.sync_sg_for_device = xen_swiotlb_sync_sg_for_device, |
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.map_sg = xen_swiotlb_map_sg, |
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.unmap_sg = xen_swiotlb_unmap_sg, |
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.map_page = xen_swiotlb_map_page, |
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.unmap_page = xen_swiotlb_unmap_page, |
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.dma_supported = xen_swiotlb_dma_supported, |
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.mmap = dma_common_mmap, |
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.get_sgtable = dma_common_get_sgtable, |
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.alloc_pages = dma_common_alloc_pages, |
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.free_pages = dma_common_free_pages, |
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};
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