417 lines
10 KiB
C
417 lines
10 KiB
C
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// 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 <jgross@suse.com>
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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/pci.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 struct device_node *xen_dt_get_node(struct device *dev)
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{
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if (dev_is_pci(dev)) {
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struct pci_dev *pdev = to_pci_dev(dev);
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struct pci_bus *bus = pdev->bus;
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/* Walk up to the root bus to look for PCI Host controller */
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while (!pci_is_root_bus(bus))
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bus = bus->parent;
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return of_node_get(bus->bridge->parent->of_node);
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}
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return of_node_get(dev->of_node);
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}
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static int xen_dt_grant_init_backend_domid(struct device *dev,
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struct device_node *np,
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domid_t *backend_domid)
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{
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struct of_phandle_args iommu_spec = { .args_count = 1 };
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if (dev_is_pci(dev)) {
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struct pci_dev *pdev = to_pci_dev(dev);
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u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
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if (of_map_id(np, rid, "iommu-map", "iommu-map-mask", &iommu_spec.np,
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iommu_spec.args)) {
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dev_dbg(dev, "Cannot translate ID\n");
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return -ESRCH;
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}
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} else {
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if (of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
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0, &iommu_spec)) {
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dev_dbg(dev, "Cannot parse iommus property\n");
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return -ESRCH;
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}
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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_dbg(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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*backend_domid = iommu_spec.args[0];
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return 0;
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}
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static int xen_grant_init_backend_domid(struct device *dev,
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domid_t *backend_domid)
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{
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struct device_node *np;
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int ret = -ENODEV;
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np = xen_dt_get_node(dev);
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if (np) {
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ret = xen_dt_grant_init_backend_domid(dev, np, backend_domid);
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of_node_put(np);
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} else if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_pv_domain()) {
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dev_info(dev, "Using dom0 as backend\n");
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*backend_domid = 0;
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ret = 0;
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}
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return ret;
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}
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||
|
|
|
||
|
|
static void xen_grant_setup_dma_ops(struct device *dev, domid_t backend_domid)
|
||
|
|
{
|
||
|
|
struct xen_grant_dma_data *data;
|
||
|
|
|
||
|
|
data = find_xen_grant_dma_data(dev);
|
||
|
|
if (data) {
|
||
|
|
dev_err(dev, "Xen grant DMA data is already created\n");
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
|
||
|
|
if (!data)
|
||
|
|
goto err;
|
||
|
|
|
||
|
|
data->backend_domid = backend_domid;
|
||
|
|
|
||
|
|
if (store_xen_grant_dma_data(dev, data)) {
|
||
|
|
dev_err(dev, "Cannot store Xen grant DMA data\n");
|
||
|
|
goto err;
|
||
|
|
}
|
||
|
|
|
||
|
|
dev->dma_ops = &xen_grant_dma_ops;
|
||
|
|
|
||
|
|
return;
|
||
|
|
|
||
|
|
err:
|
||
|
|
devm_kfree(dev, data);
|
||
|
|
dev_err(dev, "Cannot set up Xen grant DMA ops, retain platform DMA ops\n");
|
||
|
|
}
|
||
|
|
|
||
|
|
bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
|
||
|
|
{
|
||
|
|
domid_t backend_domid;
|
||
|
|
|
||
|
|
if (!xen_grant_init_backend_domid(dev->dev.parent, &backend_domid)) {
|
||
|
|
xen_grant_setup_dma_ops(dev->dev.parent, backend_domid);
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
MODULE_DESCRIPTION("Xen grant DMA-mapping layer");
|
||
|
|
MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
|
||
|
|
MODULE_LICENSE("GPL");
|