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566fb90e05
swiotlb-xen uses very different ways to allocate coherent memory on x86 vs arm. On the former it allocates memory from the page allocator, while on the later it reuses the dma-direct allocator the handles the complexities of non-coherent DMA on arm platforms. Unfortunately the complexities of trying to deal with the two cases in the swiotlb-xen.c code lead to a bug in the handling of DMA_ATTR_NO_KERNEL_MAPPING on arm. With the DMA_ATTR_NO_KERNEL_MAPPING flag the coherent memory allocator does not actually allocate coherent memory, but just a DMA handle for some memory that is DMA addressable by the device, but which does not have to have a kernel mapping. Thus dereferencing the return value will lead to kernel crashed and memory corruption. Fix this by using the dma-direct allocator directly for arm, which works perfectly fine because on arm swiotlb-xen is only used when the domain is 1:1 mapped, and then simplifying the remaining code to only cater for the x86 case with DMA coherent device. Reported-by: Rahul Singh <Rahul.Singh@arm.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Rahul Singh <rahul.singh@arm.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Tested-by: Rahul Singh <rahul.singh@arm.com>
408 lines
12 KiB
C
408 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, 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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#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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