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05ee774122
SWIOTLB implementation details should not be exposed to the rest of the kernel. This will allow to make changes to the implementation without modifying non-swiotlb code. To avoid breaking existing users, provide helper functions for the few required fields. As a bonus, using a helper function to initialize struct device allows to get rid of an #ifdef in driver core. Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Christoph Hellwig <hch@lst.de>
409 lines
12 KiB
C
409 lines
12 KiB
C
// 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 <konrad.wilk@oracle.com>
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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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#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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#include <asm/dma-mapping.h>
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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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* Quick lookup value of the bus address of the IOTLB.
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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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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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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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/* 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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#ifdef CONFIG_X86
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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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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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static void *
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xen_swiotlb_alloc_coherent(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
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{
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u64 dma_mask = dev->coherent_dma_mask;
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int order = get_order(size);
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phys_addr_t phys;
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void *ret;
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/* Align the allocation to the Xen page size */
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size = 1UL << (order + XEN_PAGE_SHIFT);
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ret = (void *)__get_free_pages(flags, get_order(size));
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if (!ret)
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return ret;
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phys = virt_to_phys(ret);
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*dma_handle = xen_phys_to_dma(dev, phys);
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if (*dma_handle + size - 1 > dma_mask ||
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range_straddles_page_boundary(phys, size)) {
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if (xen_create_contiguous_region(phys, order, fls64(dma_mask),
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dma_handle) != 0)
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goto out_free_pages;
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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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out_free_pages:
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free_pages((unsigned long)ret, get_order(size));
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return NULL;
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}
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static void
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xen_swiotlb_free_coherent(struct device *dev, size_t size, void *vaddr,
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dma_addr_t dma_handle, unsigned long attrs)
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{
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phys_addr_t phys = virt_to_phys(vaddr);
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int order = get_order(size);
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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 (WARN_ON_ONCE(dma_handle + size - 1 > dev->coherent_dma_mask) ||
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WARN_ON_ONCE(range_straddles_page_boundary(phys, size)))
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return;
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if (TestClearPageXenRemapped(virt_to_page(vaddr)))
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xen_destroy_contiguous_region(phys, order);
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free_pages((unsigned long)vaddr, get_order(size));
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}
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#endif /* CONFIG_X86 */
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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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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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* 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);
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map = swiotlb_tbl_map_single(dev, phys, size, size, 0, 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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/* 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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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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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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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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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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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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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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* 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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BUG_ON(dir == DMA_NONE);
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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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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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BUG_ON(dir == DMA_NONE);
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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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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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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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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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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, default_swiotlb_limit()) <= mask;
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}
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const struct dma_map_ops xen_swiotlb_dma_ops = {
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#ifdef CONFIG_X86
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.alloc = xen_swiotlb_alloc_coherent,
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.free = xen_swiotlb_free_coherent,
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#else
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.alloc = dma_direct_alloc,
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.free = dma_direct_free,
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#endif
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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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