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405 lines
9.6 KiB
405 lines
9.6 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Xen grant DMA-mapping layer - contains special DMA-mapping routines |
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* for providing grant references as DMA addresses to be used by frontends |
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* (e.g. virtio) in Xen guests |
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* |
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* Copyright (c) 2021, Juergen Gross <[email protected]> |
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*/ |
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#include <linux/module.h> |
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#include <linux/dma-map-ops.h> |
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#include <linux/of.h> |
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#include <linux/pfn.h> |
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#include <linux/xarray.h> |
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#include <linux/virtio_anchor.h> |
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#include <linux/virtio.h> |
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#include <xen/xen.h> |
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#include <xen/xen-ops.h> |
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#include <xen/grant_table.h> |
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struct xen_grant_dma_data { |
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/* The ID of backend domain */ |
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domid_t backend_domid; |
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/* Is device behaving sane? */ |
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bool broken; |
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}; |
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static DEFINE_XARRAY_FLAGS(xen_grant_dma_devices, XA_FLAGS_LOCK_IRQ); |
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#define XEN_GRANT_DMA_ADDR_OFF (1ULL << 63) |
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static inline dma_addr_t grant_to_dma(grant_ref_t grant) |
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{ |
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return XEN_GRANT_DMA_ADDR_OFF | ((dma_addr_t)grant << XEN_PAGE_SHIFT); |
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} |
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static inline grant_ref_t dma_to_grant(dma_addr_t dma) |
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{ |
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return (grant_ref_t)((dma & ~XEN_GRANT_DMA_ADDR_OFF) >> XEN_PAGE_SHIFT); |
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} |
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static struct xen_grant_dma_data *find_xen_grant_dma_data(struct device *dev) |
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{ |
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struct xen_grant_dma_data *data; |
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unsigned long flags; |
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xa_lock_irqsave(&xen_grant_dma_devices, flags); |
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data = xa_load(&xen_grant_dma_devices, (unsigned long)dev); |
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xa_unlock_irqrestore(&xen_grant_dma_devices, flags); |
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return data; |
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} |
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static int store_xen_grant_dma_data(struct device *dev, |
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struct xen_grant_dma_data *data) |
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{ |
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unsigned long flags; |
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int ret; |
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xa_lock_irqsave(&xen_grant_dma_devices, flags); |
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ret = xa_err(__xa_store(&xen_grant_dma_devices, (unsigned long)dev, data, |
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GFP_ATOMIC)); |
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xa_unlock_irqrestore(&xen_grant_dma_devices, flags); |
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return ret; |
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} |
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/* |
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* DMA ops for Xen frontends (e.g. virtio). |
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* |
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* Used to act as a kind of software IOMMU for Xen guests by using grants as |
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* DMA addresses. |
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* Such a DMA address is formed by using the grant reference as a frame |
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* number and setting the highest address bit (this bit is for the backend |
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* to be able to distinguish it from e.g. a mmio address). |
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*/ |
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static void *xen_grant_dma_alloc(struct device *dev, size_t size, |
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dma_addr_t *dma_handle, gfp_t gfp, |
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unsigned long attrs) |
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{ |
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struct xen_grant_dma_data *data; |
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unsigned int i, n_pages = XEN_PFN_UP(size); |
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unsigned long pfn; |
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grant_ref_t grant; |
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void *ret; |
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data = find_xen_grant_dma_data(dev); |
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if (!data) |
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return NULL; |
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if (unlikely(data->broken)) |
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return NULL; |
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ret = alloc_pages_exact(n_pages * XEN_PAGE_SIZE, gfp); |
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if (!ret) |
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return NULL; |
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pfn = virt_to_pfn(ret); |
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if (gnttab_alloc_grant_reference_seq(n_pages, &grant)) { |
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free_pages_exact(ret, n_pages * XEN_PAGE_SIZE); |
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return NULL; |
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} |
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for (i = 0; i < n_pages; i++) { |
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gnttab_grant_foreign_access_ref(grant + i, data->backend_domid, |
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pfn_to_gfn(pfn + i), 0); |
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} |
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*dma_handle = grant_to_dma(grant); |
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return ret; |
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} |
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static void xen_grant_dma_free(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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struct xen_grant_dma_data *data; |
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unsigned int i, n_pages = XEN_PFN_UP(size); |
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grant_ref_t grant; |
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data = find_xen_grant_dma_data(dev); |
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if (!data) |
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return; |
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if (unlikely(data->broken)) |
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return; |
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grant = dma_to_grant(dma_handle); |
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for (i = 0; i < n_pages; i++) { |
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if (unlikely(!gnttab_end_foreign_access_ref(grant + i))) { |
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dev_alert(dev, "Grant still in use by backend domain, disabled for further use\n"); |
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data->broken = true; |
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return; |
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} |
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} |
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gnttab_free_grant_reference_seq(grant, n_pages); |
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free_pages_exact(vaddr, n_pages * XEN_PAGE_SIZE); |
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} |
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static struct page *xen_grant_dma_alloc_pages(struct device *dev, size_t size, |
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dma_addr_t *dma_handle, |
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enum dma_data_direction dir, |
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gfp_t gfp) |
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{ |
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void *vaddr; |
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vaddr = xen_grant_dma_alloc(dev, size, dma_handle, gfp, 0); |
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if (!vaddr) |
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return NULL; |
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return virt_to_page(vaddr); |
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} |
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static void xen_grant_dma_free_pages(struct device *dev, size_t size, |
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struct page *vaddr, dma_addr_t dma_handle, |
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enum dma_data_direction dir) |
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{ |
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xen_grant_dma_free(dev, size, page_to_virt(vaddr), dma_handle, 0); |
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} |
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static dma_addr_t xen_grant_dma_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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struct xen_grant_dma_data *data; |
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unsigned long dma_offset = xen_offset_in_page(offset), |
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pfn_offset = XEN_PFN_DOWN(offset); |
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unsigned int i, n_pages = XEN_PFN_UP(dma_offset + size); |
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grant_ref_t grant; |
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dma_addr_t dma_handle; |
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if (WARN_ON(dir == DMA_NONE)) |
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return DMA_MAPPING_ERROR; |
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data = find_xen_grant_dma_data(dev); |
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if (!data) |
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return DMA_MAPPING_ERROR; |
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if (unlikely(data->broken)) |
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return DMA_MAPPING_ERROR; |
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if (gnttab_alloc_grant_reference_seq(n_pages, &grant)) |
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return DMA_MAPPING_ERROR; |
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for (i = 0; i < n_pages; i++) { |
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gnttab_grant_foreign_access_ref(grant + i, data->backend_domid, |
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pfn_to_gfn(page_to_xen_pfn(page) + i + pfn_offset), |
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dir == DMA_TO_DEVICE); |
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} |
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dma_handle = grant_to_dma(grant) + dma_offset; |
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return dma_handle; |
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} |
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static void xen_grant_dma_unmap_page(struct device *dev, dma_addr_t dma_handle, |
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size_t size, enum dma_data_direction dir, |
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unsigned long attrs) |
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{ |
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struct xen_grant_dma_data *data; |
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unsigned long dma_offset = xen_offset_in_page(dma_handle); |
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unsigned int i, n_pages = XEN_PFN_UP(dma_offset + size); |
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grant_ref_t grant; |
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if (WARN_ON(dir == DMA_NONE)) |
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return; |
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data = find_xen_grant_dma_data(dev); |
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if (!data) |
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return; |
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if (unlikely(data->broken)) |
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return; |
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grant = dma_to_grant(dma_handle); |
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for (i = 0; i < n_pages; i++) { |
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if (unlikely(!gnttab_end_foreign_access_ref(grant + i))) { |
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dev_alert(dev, "Grant still in use by backend domain, disabled for further use\n"); |
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data->broken = true; |
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return; |
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} |
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} |
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gnttab_free_grant_reference_seq(grant, n_pages); |
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} |
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static void xen_grant_dma_unmap_sg(struct device *dev, struct scatterlist *sg, |
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int nents, enum dma_data_direction dir, |
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unsigned long attrs) |
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{ |
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struct scatterlist *s; |
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unsigned int i; |
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if (WARN_ON(dir == DMA_NONE)) |
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return; |
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for_each_sg(sg, s, nents, i) |
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xen_grant_dma_unmap_page(dev, s->dma_address, sg_dma_len(s), dir, |
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attrs); |
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} |
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static int xen_grant_dma_map_sg(struct device *dev, struct scatterlist *sg, |
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int nents, enum dma_data_direction dir, |
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unsigned long attrs) |
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{ |
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struct scatterlist *s; |
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unsigned int i; |
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if (WARN_ON(dir == DMA_NONE)) |
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return -EINVAL; |
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for_each_sg(sg, s, nents, i) { |
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s->dma_address = xen_grant_dma_map_page(dev, sg_page(s), s->offset, |
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s->length, dir, attrs); |
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if (s->dma_address == DMA_MAPPING_ERROR) |
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goto out; |
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sg_dma_len(s) = s->length; |
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} |
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return nents; |
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out: |
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xen_grant_dma_unmap_sg(dev, sg, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); |
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sg_dma_len(sg) = 0; |
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return -EIO; |
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} |
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static int xen_grant_dma_supported(struct device *dev, u64 mask) |
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{ |
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return mask == DMA_BIT_MASK(64); |
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} |
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static const struct dma_map_ops xen_grant_dma_ops = { |
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.alloc = xen_grant_dma_alloc, |
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.free = xen_grant_dma_free, |
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.alloc_pages = xen_grant_dma_alloc_pages, |
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.free_pages = xen_grant_dma_free_pages, |
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.mmap = dma_common_mmap, |
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.get_sgtable = dma_common_get_sgtable, |
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.map_page = xen_grant_dma_map_page, |
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.unmap_page = xen_grant_dma_unmap_page, |
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.map_sg = xen_grant_dma_map_sg, |
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.unmap_sg = xen_grant_dma_unmap_sg, |
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.dma_supported = xen_grant_dma_supported, |
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}; |
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static bool xen_is_dt_grant_dma_device(struct device *dev) |
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{ |
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struct device_node *iommu_np; |
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bool has_iommu; |
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iommu_np = of_parse_phandle(dev->of_node, "iommus", 0); |
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has_iommu = iommu_np && |
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of_device_is_compatible(iommu_np, "xen,grant-dma"); |
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of_node_put(iommu_np); |
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return has_iommu; |
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} |
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bool xen_is_grant_dma_device(struct device *dev) |
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{ |
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/* XXX Handle only DT devices for now */ |
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if (dev->of_node) |
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return xen_is_dt_grant_dma_device(dev); |
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return false; |
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} |
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bool xen_virtio_mem_acc(struct virtio_device *dev) |
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{ |
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if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_pv_domain()) |
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return true; |
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return xen_is_grant_dma_device(dev->dev.parent); |
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} |
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static int xen_dt_grant_init_backend_domid(struct device *dev, |
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struct xen_grant_dma_data *data) |
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{ |
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struct of_phandle_args iommu_spec; |
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if (of_parse_phandle_with_args(dev->of_node, "iommus", "#iommu-cells", |
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0, &iommu_spec)) { |
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dev_err(dev, "Cannot parse iommus property\n"); |
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return -ESRCH; |
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} |
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if (!of_device_is_compatible(iommu_spec.np, "xen,grant-dma") || |
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iommu_spec.args_count != 1) { |
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dev_err(dev, "Incompatible IOMMU node\n"); |
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of_node_put(iommu_spec.np); |
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return -ESRCH; |
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} |
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of_node_put(iommu_spec.np); |
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/* |
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* The endpoint ID here means the ID of the domain where the |
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* corresponding backend is running |
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*/ |
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data->backend_domid = iommu_spec.args[0]; |
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return 0; |
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} |
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void xen_grant_setup_dma_ops(struct device *dev) |
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{ |
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struct xen_grant_dma_data *data; |
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data = find_xen_grant_dma_data(dev); |
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if (data) { |
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dev_err(dev, "Xen grant DMA data is already created\n"); |
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return; |
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} |
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data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); |
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if (!data) |
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goto err; |
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if (dev->of_node) { |
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if (xen_dt_grant_init_backend_domid(dev, data)) |
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goto err; |
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} else if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT)) { |
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dev_info(dev, "Using dom0 as backend\n"); |
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data->backend_domid = 0; |
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} else { |
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/* XXX ACPI device unsupported for now */ |
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goto err; |
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} |
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if (store_xen_grant_dma_data(dev, data)) { |
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dev_err(dev, "Cannot store Xen grant DMA data\n"); |
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goto err; |
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} |
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dev->dma_ops = &xen_grant_dma_ops; |
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return; |
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err: |
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devm_kfree(dev, data); |
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dev_err(dev, "Cannot set up Xen grant DMA ops, retain platform DMA ops\n"); |
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} |
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bool xen_virtio_restricted_mem_acc(struct virtio_device *dev) |
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{ |
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bool ret = xen_virtio_mem_acc(dev); |
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if (ret) |
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xen_grant_setup_dma_ops(dev->dev.parent); |
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return ret; |
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} |
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MODULE_DESCRIPTION("Xen grant DMA-mapping layer"); |
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MODULE_AUTHOR("Juergen Gross <[email protected]>"); |
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MODULE_LICENSE("GPL");
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