Backing for operations on the IOMMU object, including DMA
mapping and unmapping.
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
drivers/vfio/vfio_iommu.c | 611 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 611 insertions(+), 0 deletions(-)
create mode 100644 drivers/vfio/vfio_iommu.c
diff --git a/drivers/vfio/vfio_iommu.c b/drivers/vfio/vfio_iommu.c
new file mode 100644
index 0000000..49e6b2d
--- /dev/null
+++ b/drivers/vfio/vfio_iommu.c
@@ -0,0 +1,611 @@
+/*
+ * VFIO: IOMMU DMA mapping support
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All rights reserved.
+ * Author: Alex Williamson <alex.williamson@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Derived from original vfio:
+ * Copyright 2010 Cisco Systems, Inc. All rights reserved.
+ * Author: Tom Lyon, pugs@xxxxxxxxx
+ */
+
+#include <linux/compat.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/iommu.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/vfio.h>
+#include <linux/workqueue.h>
+
+#include "vfio_private.h"
+
+struct vfio_dma_map_entry {
+ struct list_head list;
+ dma_addr_t iova; /* Device address */
+ unsigned long vaddr; /* Process virtual addr */
+ long npage; /* Number of pages */
+ int prot; /* IOMMU_READ/WRITE */
+};
+
+/*
+ * This code handles mapping and unmapping of user data buffers
+ * into DMA'ble space using the IOMMU
+ */
+
+#define NPAGE_TO_SIZE(npage) ((size_t)(npage) << PAGE_SHIFT)
+
+struct vwork {
+ struct mm_struct *mm;
+ long npage;
+ struct work_struct work;
+};
+
+/* delayed decrement/increment for locked_vm */
+static void vfio_lock_acct_bg(struct work_struct *work)
+{
+ struct vwork *vwork = container_of(work, struct vwork, work);
+ struct mm_struct *mm;
+
+ mm = vwork->mm;
+ down_write(&mm->mmap_sem);
+ mm->locked_vm += vwork->npage;
+ up_write(&mm->mmap_sem);
+ mmput(mm);
+ kfree(vwork);
+}
+
+static void vfio_lock_acct(long npage)
+{
+ struct vwork *vwork;
+ struct mm_struct *mm;
+
+ if (!current->mm)
+ return; /* process exited */
+
+ if (down_write_trylock(¤t->mm->mmap_sem)) {
+ current->mm->locked_vm += npage;
+ up_write(¤t->mm->mmap_sem);
+ return;
+ }
+
+ /*
+ * Couldn't get mmap_sem lock, so must setup to update
+ * mm->locked_vm later. If locked_vm were atomic, we
+ * wouldn't need this silliness
+ */
+ vwork = kmalloc(sizeof(struct vwork), GFP_KERNEL);
+ if (!vwork)
+ return;
+ mm = get_task_mm(current);
+ if (!mm) {
+ kfree(vwork);
+ return;
+ }
+ INIT_WORK(&vwork->work, vfio_lock_acct_bg);
+ vwork->mm = mm;
+ vwork->npage = npage;
+ schedule_work(&vwork->work);
+}
+
+/*
+ * Some mappings aren't backed by a struct page, for example an mmap'd
+ * MMIO range for our own or another device. These use a different
+ * pfn conversion and shouldn't be tracked as locked pages.
+ */
+static bool is_invalid_reserved_pfn(unsigned long pfn)
+{
+ if (pfn_valid(pfn)) {
+ bool reserved;
+ struct page *tail = pfn_to_page(pfn);
+ struct page *head = compound_trans_head(tail);
+ reserved = !!(PageReserved(head));
+ if (head != tail) {
+ /*
+ * "head" is not a dangling pointer
+ * (compound_trans_head takes care of that)
+ * but the hugepage may have been split
+ * from under us (and we may not hold a
+ * reference count on the head page so it can
+ * be reused before we run PageReferenced), so
+ * we've to check PageTail before returning
+ * what we just read.
+ */
+ smp_rmb();
+ if (PageTail(tail))
+ return reserved;
+ }
+ return PageReserved(tail);
+ }
+
+ return true;
+}
+
+static int put_pfn(unsigned long pfn, int prot)
+{
+ if (!is_invalid_reserved_pfn(pfn)) {
+ struct page *page = pfn_to_page(pfn);
+ if (prot & IOMMU_WRITE)
+ SetPageDirty(page);
+ put_page(page);
+ return 1;
+ }
+ return 0;
+}
+
+/* Unmap DMA region */
+static long __vfio_dma_do_unmap(struct vfio_iommu *iommu, dma_addr_t iova,
+ long npage, int prot)
+{
+ long i, unlocked = 0;
+
+ for (i = 0; i < npage; i++, iova += PAGE_SIZE) {
+ unsigned long pfn;
+
+ pfn = iommu_iova_to_phys(iommu->domain, iova) >> PAGE_SHIFT;
+ if (pfn) {
+ iommu_unmap(iommu->domain, iova, PAGE_SIZE);
+ unlocked += put_pfn(pfn, prot);
+ }
+ }
+ return unlocked;
+}
+
+static void vfio_dma_unmap(struct vfio_iommu *iommu, dma_addr_t iova,
+ long npage, int prot)
+{
+ long unlocked;
+
+ unlocked = __vfio_dma_do_unmap(iommu, iova, npage, prot);
+ vfio_lock_acct(-unlocked);
+}
+
+/* Unmap ALL DMA regions */
+void vfio_iommu_unmapall(struct vfio_iommu *iommu)
+{
+ struct list_head *pos, *tmp;
+
+ mutex_lock(&iommu->lock);
+ list_for_each_safe(pos, tmp, &iommu->dma_list) {
+ struct vfio_dma_map_entry *dma;
+
+ dma = list_entry(pos, struct vfio_dma_map_entry, list);
+ vfio_dma_unmap(iommu, dma->iova, dma->npage, dma->prot);
+ list_del(&dma->list);
+ kfree(dma);
+ }
+ mutex_unlock(&iommu->lock);
+}
+
+static int vaddr_get_pfn(unsigned long vaddr, int prot, unsigned long *pfn)
+{
+ struct page *page[1];
+ struct vm_area_struct *vma;
+ int ret = -EFAULT;
+
+ if (get_user_pages_fast(vaddr, 1, !!(prot & IOMMU_WRITE), page) == 1) {
+ *pfn = page_to_pfn(page[0]);
+ return 0;
+ }
+
+ down_read(¤t->mm->mmap_sem);
+
+ vma = find_vma_intersection(current->mm, vaddr, vaddr + 1);
+
+ if (vma && vma->vm_flags & VM_PFNMAP) {
+ *pfn = ((vaddr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+ if (is_invalid_reserved_pfn(*pfn))
+ ret = 0;
+ }
+
+ up_read(¤t->mm->mmap_sem);
+
+ return ret;
+}
+
+/* Map DMA region */
+static int __vfio_dma_map(struct vfio_iommu *iommu, dma_addr_t iova,
+ unsigned long vaddr, long npage, int prot)
+{
+ dma_addr_t start = iova;
+ long i, locked = 0;
+ int ret;
+
+ /* Verify that pages are not already mapped */
+ for (i = 0; i < npage; i++, iova += PAGE_SIZE)
+ if (iommu_iova_to_phys(iommu->domain, iova))
+ return -EBUSY;
+
+ iova = start;
+
+ if (iommu->cache)
+ prot |= IOMMU_CACHE;
+
+ /*
+ * XXX We break mappings into pages and use get_user_pages_fast to
+ * pin the pages in memory. It's been suggested that mlock might
+ * provide a more efficient mechanism, but nothing prevents the
+ * user from munlocking the pages, which could then allow the user
+ * access to random host memory. We also have no guarantee from the
+ * IOMMU API that the iommu driver can unmap sub-pages of previous
+ * mappings. This means we might lose an entire range if a single
+ * page within it is unmapped. Single page mappings are inefficient,
+ * but provide the most flexibility for now.
+ */
+ for (i = 0; i < npage; i++, iova += PAGE_SIZE, vaddr += PAGE_SIZE) {
+ unsigned long pfn = 0;
+
+ ret = vaddr_get_pfn(vaddr, prot, &pfn);
+ if (ret) {
+ __vfio_dma_do_unmap(iommu, start, i, prot);
+ return ret;
+ }
+
+ /*
+ * Only add actual locked pages to accounting
+ * XXX We're effectively marking a page locked for every
+ * IOVA page even though it's possible the user could be
+ * backing multiple IOVAs with the same vaddr. This over-
+ * penalizes the user process, but we currently have no
+ * easy way to do this properly.
+ */
+ if (!is_invalid_reserved_pfn(pfn))
+ locked++;
+
+ ret = iommu_map(iommu->domain, iova,
+ (phys_addr_t)pfn << PAGE_SHIFT,
+ PAGE_SIZE, prot);
+ if (ret) {
+ /* Back out mappings on error */
+ put_pfn(pfn, prot);
+ __vfio_dma_do_unmap(iommu, start, i, prot);
+ return ret;
+ }
+ }
+ vfio_lock_acct(locked);
+ return 0;
+}
+
+static inline bool ranges_overlap(dma_addr_t start1, size_t size1,
+ dma_addr_t start2, size_t size2)
+{
+ if (start1 < start2)
+ return (start2 - start1 < size1);
+ else if (start2 < start1)
+ return (start1 - start2 < size2);
+ return (size1 > 0 && size2 > 0);
+}
+
+static struct vfio_dma_map_entry *vfio_find_dma(struct vfio_iommu *iommu,
+ dma_addr_t start, size_t size)
+{
+ struct list_head *pos;
+
+ list_for_each(pos, &iommu->dma_list) {
+ struct vfio_dma_map_entry *dma;
+
+ dma = list_entry(pos, struct vfio_dma_map_entry, list);
+ if (ranges_overlap(dma->iova, NPAGE_TO_SIZE(dma->npage),
+ start, size))
+ return dma;
+ }
+ return NULL;
+}
+
+static long vfio_remove_dma_overlap(struct vfio_iommu *iommu, dma_addr_t start,
+ size_t size, struct vfio_dma_map_entry *dma)
+{
+ struct vfio_dma_map_entry *split;
+ long npage_lo, npage_hi;
+
+ /* Existing dma region is completely covered, unmap all */
+ if (start <= dma->iova &&
+ start + size >= dma->iova + NPAGE_TO_SIZE(dma->npage)) {
+ vfio_dma_unmap(iommu, dma->iova, dma->npage, dma->prot);
+ list_del(&dma->list);
+ npage_lo = dma->npage;
+ kfree(dma);
+ return npage_lo;
+ }
+
+ /* Overlap low address of existing range */
+ if (start <= dma->iova) {
+ size_t overlap;
+
+ overlap = start + size - dma->iova;
+ npage_lo = overlap >> PAGE_SHIFT;
+
+ vfio_dma_unmap(iommu, dma->iova, npage_lo, dma->prot);
+ dma->iova += overlap;
+ dma->vaddr += overlap;
+ dma->npage -= npage_lo;
+ return npage_lo;
+ }
+
+ /* Overlap high address of existing range */
+ if (start + size >= dma->iova + NPAGE_TO_SIZE(dma->npage)) {
+ size_t overlap;
+
+ overlap = dma->iova + NPAGE_TO_SIZE(dma->npage) - start;
+ npage_hi = overlap >> PAGE_SHIFT;
+
+ vfio_dma_unmap(iommu, start, npage_hi, dma->prot);
+ dma->npage -= npage_hi;
+ return npage_hi;
+ }
+
+ /* Split existing */
+ npage_lo = (start - dma->iova) >> PAGE_SHIFT;
+ npage_hi = dma->npage - (size >> PAGE_SHIFT) - npage_lo;
+
+ split = kzalloc(sizeof *split, GFP_KERNEL);
+ if (!split)
+ return -ENOMEM;
+
+ vfio_dma_unmap(iommu, start, size >> PAGE_SHIFT, dma->prot);
+
+ dma->npage = npage_lo;
+
+ split->npage = npage_hi;
+ split->iova = start + size;
+ split->vaddr = dma->vaddr + NPAGE_TO_SIZE(npage_lo) + size;
+ split->prot = dma->prot;
+ list_add(&split->list, &iommu->dma_list);
+ return size >> PAGE_SHIFT;
+}
+
+static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
+ struct vfio_dma_unmap *unmap)
+{
+ long ret = 0, npage = unmap->size >> PAGE_SHIFT;
+ struct list_head *pos, *tmp;
+ uint64_t mask;
+
+ mask = ((uint64_t)1 << __ffs(iommu->domain->ops->pgsize_bitmap)) - 1;
+
+ if (unmap->iova & mask)
+ return -EINVAL;
+ if (unmap->size & mask)
+ return -EINVAL;
+
+ /* XXX We still break these down into PAGE_SIZE */
+ WARN_ON(mask & PAGE_MASK);
+
+ mutex_lock(&iommu->lock);
+
+ list_for_each_safe(pos, tmp, &iommu->dma_list) {
+ struct vfio_dma_map_entry *dma;
+
+ dma = list_entry(pos, struct vfio_dma_map_entry, list);
+ if (ranges_overlap(dma->iova, NPAGE_TO_SIZE(dma->npage),
+ unmap->iova, unmap->size)) {
+ ret = vfio_remove_dma_overlap(iommu, unmap->iova,
+ unmap->size, dma);
+ if (ret > 0)
+ npage -= ret;
+ if (ret < 0 || npage == 0)
+ break;
+ }
+ }
+ mutex_unlock(&iommu->lock);
+ return ret > 0 ? 0 : (int)ret;
+}
+
+static int vfio_dma_do_map(struct vfio_iommu *iommu, struct vfio_dma_map *map)
+{
+ struct vfio_dma_map_entry *dma, *pdma = NULL;
+ dma_addr_t iova = map->iova;
+ unsigned long locked, lock_limit, vaddr = map->vaddr;
+ size_t size = map->size;
+ int ret = 0, prot = 0;
+ uint64_t mask;
+ long npage;
+
+ mask = ((uint64_t)1 << __ffs(iommu->domain->ops->pgsize_bitmap)) - 1;
+
+ /* READ/WRITE from device perspective */
+ if (map->flags & VFIO_DMA_MAP_FLAG_WRITE)
+ prot |= IOMMU_WRITE;
+ if (map->flags & VFIO_DMA_MAP_FLAG_READ)
+ prot |= IOMMU_READ;
+
+ if (!prot)
+ return -EINVAL; /* No READ/WRITE? */
+
+ if (vaddr & mask)
+ return -EINVAL;
+ if (iova & mask)
+ return -EINVAL;
+ if (size & mask)
+ return -EINVAL;
+
+ /* XXX We still break these down into PAGE_SIZE */
+ WARN_ON(mask & PAGE_MASK);
+
+ /* Don't allow IOVA wrap */
+ if (iova + size && iova + size < iova)
+ return -EINVAL;
+
+ /* Don't allow virtual address wrap */
+ if (vaddr + size && vaddr + size < vaddr)
+ return -EINVAL;
+
+ npage = size >> PAGE_SHIFT;
+ if (!npage)
+ return -EINVAL;
+
+ mutex_lock(&iommu->lock);
+
+ if (vfio_find_dma(iommu, iova, size)) {
+ ret = -EBUSY;
+ goto out_lock;
+ }
+
+ /* account for locked pages */
+ locked = current->mm->locked_vm + npage;
+ lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+ if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
+ printk(KERN_WARNING "%s: RLIMIT_MEMLOCK (%ld) exceeded\n",
+ __func__, rlimit(RLIMIT_MEMLOCK));
+ ret = -ENOMEM;
+ goto out_lock;
+ }
+
+ ret = __vfio_dma_map(iommu, iova, vaddr, npage, prot);
+ if (ret)
+ goto out_lock;
+
+ /* Check if we abut a region below - nothing below 0 */
+ if (iova) {
+ dma = vfio_find_dma(iommu, iova - 1, 1);
+ if (dma && dma->prot == prot &&
+ dma->vaddr + NPAGE_TO_SIZE(dma->npage) == vaddr) {
+
+ dma->npage += npage;
+ iova = dma->iova;
+ vaddr = dma->vaddr;
+ npage = dma->npage;
+ size = NPAGE_TO_SIZE(npage);
+
+ pdma = dma;
+ }
+ }
+
+ /* Check if we abut a region above - nothing above ~0 + 1 */
+ if (iova + size) {
+ dma = vfio_find_dma(iommu, iova + size, 1);
+ if (dma && dma->prot == prot &&
+ dma->vaddr == vaddr + size) {
+
+ dma->npage += npage;
+ dma->iova = iova;
+ dma->vaddr = vaddr;
+
+ /*
+ * If merged above and below, remove previously
+ * merged entry. New entry covers it.
+ */
+ if (pdma) {
+ list_del(&pdma->list);
+ kfree(pdma);
+ }
+ pdma = dma;
+ }
+ }
+
+ /* Isolated, new region */
+ if (!pdma) {
+ dma = kzalloc(sizeof *dma, GFP_KERNEL);
+ if (!dma) {
+ ret = -ENOMEM;
+ vfio_dma_unmap(iommu, iova, npage, prot);
+ goto out_lock;
+ }
+
+ dma->npage = npage;
+ dma->iova = iova;
+ dma->vaddr = vaddr;
+ dma->prot = prot;
+ list_add(&dma->list, &iommu->dma_list);
+ }
+
+out_lock:
+ mutex_unlock(&iommu->lock);
+ return ret;
+}
+
+static int vfio_iommu_release(struct inode *inode, struct file *filep)
+{
+ struct vfio_iommu *iommu = filep->private_data;
+
+ vfio_release_iommu(iommu);
+ return 0;
+}
+
+static long vfio_iommu_unl_ioctl(struct file *filep,
+ unsigned int cmd, unsigned long arg)
+{
+ struct vfio_iommu *iommu = filep->private_data;
+ unsigned long minsz;
+
+ if (cmd == VFIO_IOMMU_GET_INFO) {
+ struct vfio_iommu_info info;
+
+ minsz = offsetofend(struct vfio_iommu_info, iova_pgsizes);
+
+ if (copy_from_user(&info, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (info.argsz < minsz)
+ return -EINVAL;
+
+ info.flags = 0;
+
+ /*
+ * XXX Need to define an interface in IOMMU API for this.
+ * Currently only compatible with x86 VT-d/AMD-Vi which
+ * do page table based mapping and have no constraints here.
+ */
+ info.iova_start = 0;
+ info.iova_size = ~info.iova_start;
+ info.iova_entries = ~info.iova_start;
+ info.iova_pgsizes = iommu->domain->ops->pgsize_bitmap;
+
+ return copy_to_user((void __user *)arg, &info, minsz);
+
+ } else if (cmd == VFIO_IOMMU_MAP_DMA) {
+ struct vfio_dma_map map;
+ uint32_t mask = VFIO_DMA_MAP_FLAG_READ |
+ VFIO_DMA_MAP_FLAG_WRITE;
+
+ minsz = offsetofend(struct vfio_dma_map, size);
+
+ if (copy_from_user(&map, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (map.argsz < minsz || map.flags & ~mask)
+ return -EINVAL;
+
+ return vfio_dma_do_map(iommu, &map);
+
+ } else if (cmd == VFIO_IOMMU_UNMAP_DMA) {
+ struct vfio_dma_unmap unmap;
+
+ minsz = offsetofend(struct vfio_dma_unmap, size);
+
+ if (copy_from_user(&unmap, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (unmap.argsz < minsz || unmap.flags)
+ return -EINVAL;
+
+ return vfio_dma_do_unmap(iommu, &unmap);
+ }
+
+ return -ENOTTY;
+}
+
+#ifdef CONFIG_COMPAT
+static long vfio_iommu_compat_ioctl(struct file *filep,
+ unsigned int cmd, unsigned long arg)
+{
+ arg = (unsigned long)compat_ptr(arg);
+ return vfio_iommu_unl_ioctl(filep, cmd, arg);
+}
+#endif /* CONFIG_COMPAT */
+
+const struct file_operations vfio_iommu_fops = {
+ .owner = THIS_MODULE,
+ .release = vfio_iommu_release,
+ .unlocked_ioctl = vfio_iommu_unl_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = vfio_iommu_compat_ioctl,
+#endif
+};
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