[v7,4/7] vfio: allow reserved iova registration

Message ID 1461086687-2658-5-git-send-email-eric.auger@linaro.org
State New
Headers show

Commit Message

Auger Eric April 19, 2016, 5:24 p.m.
The user is allowed to [un]register a reserved IOVA range by using the
DMA MAP API and setting the new flag: VFIO_DMA_MAP_FLAG_MSI_RESERVED_IOVA.
It provides the base address and the size. This region is stored in the
vfio_dma rb tree. At that point the iova range is not mapped to any target
address yet. The host kernel will use those iova when needed, typically
when the VFIO-PCI driver allocates its MSIs.

Signed-off-by: Eric Auger <eric.auger@linaro.org>

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>


---
v6 -> v7:
- use iommu_free_reserved_iova_domain
- convey prot attributes downto dma-reserved-iommu iova domain creation
- reserved bindings teardown now performed on iommu domain destruction
- rename VFIO_DMA_MAP_FLAG_MSI_RESERVED_IOVA into
         VFIO_DMA_MAP_FLAG_RESERVED_MSI_IOVA
- change title
- pass the protection attribute to dma-reserved-iommu API

v3 -> v4:
- use iommu_alloc/free_reserved_iova_domain exported by dma-reserved-iommu
- protect vfio_register_reserved_iova_range implementation with
  CONFIG_IOMMU_DMA_RESERVED
- handle unregistration by user-space and on vfio_iommu_type1 release

v1 -> v2:
- set returned value according to alloc_reserved_iova_domain result
- free the iova domains in case any error occurs

RFC v1 -> v1:
- takes into account Alex comments, based on
  [RFC PATCH 1/6] vfio: Add interface for add/del reserved iova region:
- use the existing dma map/unmap ioctl interface with a flag to register
  a reserved IOVA range. A single reserved iova region is allowed.
---
 drivers/vfio/vfio_iommu_type1.c | 138 +++++++++++++++++++++++++++++++++++++++-
 include/uapi/linux/vfio.h       |   9 ++-
 2 files changed, 145 insertions(+), 2 deletions(-)

-- 
1.9.1

Patch

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 93c17d9..fa6b8b1 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -454,6 +454,27 @@  static void vfio_destroy_reserved(struct vfio_iommu *iommu)
 		iommu_free_reserved_iova_domain(d->domain);
 }
 
+static int vfio_create_reserved(struct vfio_iommu *iommu,
+				dma_addr_t iova, size_t size,
+				int prot, unsigned long order)
+{
+	struct vfio_domain *d;
+	int ret = 0;
+
+	list_for_each_entry(d, &iommu->domain_list, next) {
+		ret = iommu_alloc_reserved_iova_domain(d->domain, iova,
+						       size, prot, order);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		list_for_each_entry(d, &iommu->domain_list, next)
+			iommu_free_reserved_iova_domain(d->domain);
+	}
+	return ret;
+}
+
 static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
 {
 	if (likely(dma->type == VFIO_IOVA_USER))
@@ -705,6 +726,110 @@  static int vfio_dma_do_map(struct vfio_iommu *iommu,
 	return ret;
 }
 
+static int vfio_register_reserved_iova_range(struct vfio_iommu *iommu,
+			   struct vfio_iommu_type1_dma_map *map)
+{
+	dma_addr_t iova = map->iova;
+	size_t size = map->size;
+	int ret = 0, prot = 0;
+	struct vfio_dma *dma;
+	unsigned long order;
+	uint64_t mask;
+
+	/* Verify that none of our __u64 fields overflow */
+	if (map->size != size || map->iova != iova)
+		return -EINVAL;
+
+	order =  __ffs(vfio_pgsize_bitmap(iommu));
+	mask = ((uint64_t)1 << order) - 1;
+
+	WARN_ON(mask & PAGE_MASK);
+
+	if (!size || (size | iova) & mask)
+		return -EINVAL;
+
+	/* Don't allow IOVA address wrap */
+	if (iova + size - 1 < iova)
+		return -EINVAL;
+
+	mutex_lock(&iommu->lock);
+
+	if (vfio_find_dma(iommu, iova, size, VFIO_IOVA_ANY)) {
+		ret =  -EEXIST;
+		goto unlock;
+	}
+
+	dma = kzalloc(sizeof(*dma), GFP_KERNEL);
+	if (!dma) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	dma->iova = iova;
+	dma->size = size;
+	dma->type = VFIO_IOVA_RESERVED;
+
+	if (map->flags & VFIO_DMA_MAP_FLAG_READ)
+		prot = IOMMU_READ;
+	if (map->flags & VFIO_DMA_MAP_FLAG_WRITE)
+		prot |= IOMMU_WRITE;
+
+	ret = vfio_create_reserved(iommu, iova, size, prot, order);
+	if (ret)
+		goto free_unlock;
+
+	vfio_link_dma(iommu, dma);
+	goto unlock;
+
+free_unlock:
+	kfree(dma);
+unlock:
+	mutex_unlock(&iommu->lock);
+	return ret;
+}
+
+static int vfio_unregister_reserved_iova_range(struct vfio_iommu *iommu,
+				struct vfio_iommu_type1_dma_unmap *unmap)
+{
+	dma_addr_t iova = unmap->iova;
+	struct vfio_dma *dma;
+	size_t size = unmap->size;
+	uint64_t mask;
+	unsigned long order;
+	int ret = -EINVAL;
+
+	/* Verify that none of our __u64 fields overflow */
+	if (unmap->size != size || unmap->iova != iova)
+		return ret;
+
+	order =  __ffs(vfio_pgsize_bitmap(iommu));
+	mask = ((uint64_t)1 << order) - 1;
+
+	WARN_ON(mask & PAGE_MASK);
+
+	if (!size || (size | iova) & mask)
+		return ret;
+
+	/* Don't allow IOVA address wrap */
+	if (iova + size - 1 < iova)
+		return ret;
+
+	mutex_lock(&iommu->lock);
+
+	dma = vfio_find_dma(iommu, iova, size, VFIO_IOVA_RESERVED);
+
+	if (dma && (dma->iova == iova) && (dma->size == size)) {
+		unmap->size =  dma->size;
+		vfio_remove_dma(iommu, dma);
+		ret = 0;
+		goto unlock;
+	}
+	unmap->size = 0;
+unlock:
+	mutex_unlock(&iommu->lock);
+	return ret;
+}
+
 static int vfio_bus_type(struct device *dev, void *data)
 {
 	struct bus_type **bus = data;
@@ -1074,7 +1199,8 @@  static long vfio_iommu_type1_ioctl(void *iommu_data,
 	} else if (cmd == VFIO_IOMMU_MAP_DMA) {
 		struct vfio_iommu_type1_dma_map map;
 		uint32_t mask = VFIO_DMA_MAP_FLAG_READ |
-				VFIO_DMA_MAP_FLAG_WRITE;
+				VFIO_DMA_MAP_FLAG_WRITE |
+				VFIO_DMA_MAP_FLAG_RESERVED_MSI_IOVA;
 
 		minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
 
@@ -1084,6 +1210,9 @@  static long vfio_iommu_type1_ioctl(void *iommu_data,
 		if (map.argsz < minsz || map.flags & ~mask)
 			return -EINVAL;
 
+		if (map.flags & VFIO_DMA_MAP_FLAG_RESERVED_MSI_IOVA)
+			return vfio_register_reserved_iova_range(iommu, &map);
+
 		return vfio_dma_do_map(iommu, &map);
 
 	} else if (cmd == VFIO_IOMMU_UNMAP_DMA) {
@@ -1098,6 +1227,13 @@  static long vfio_iommu_type1_ioctl(void *iommu_data,
 		if (unmap.argsz < minsz || unmap.flags)
 			return -EINVAL;
 
+		if (unmap.flags & VFIO_DMA_MAP_FLAG_RESERVED_MSI_IOVA) {
+			ret = vfio_unregister_reserved_iova_range(iommu,
+								  &unmap);
+			if (ret)
+				return ret;
+		}
+
 		ret = vfio_dma_do_unmap(iommu, &unmap);
 		if (ret)
 			return ret;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 255a211..0637f35 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -498,12 +498,18 @@  struct vfio_iommu_type1_info {
  *
  * Map process virtual addresses to IO virtual addresses using the
  * provided struct vfio_dma_map. Caller sets argsz. READ &/ WRITE required.
+ *
+ * In case RESERVED_MSI_IOVA flag is set, the API only aims at registering an
+ * IOVA region that will be used on some platforms to map the host MSI frames.
+ * In that specific case, vaddr is ignored.
  */
 struct vfio_iommu_type1_dma_map {
 	__u32	argsz;
 	__u32	flags;
 #define VFIO_DMA_MAP_FLAG_READ (1 << 0)		/* readable from device */
 #define VFIO_DMA_MAP_FLAG_WRITE (1 << 1)	/* writable from device */
+/* reserved iova for MSI vectors*/
+#define VFIO_DMA_MAP_FLAG_RESERVED_MSI_IOVA (1 << 2)
 	__u64	vaddr;				/* Process virtual address */
 	__u64	iova;				/* IO virtual address */
 	__u64	size;				/* Size of mapping (bytes) */
@@ -519,7 +525,8 @@  struct vfio_iommu_type1_dma_map {
  * Caller sets argsz.  The actual unmapped size is returned in the size
  * field.  No guarantee is made to the user that arbitrary unmaps of iova
  * or size different from those used in the original mapping call will
- * succeed.
+ * succeed. A Reserved DMA region must be unmapped with RESERVED_MSI_IOVA
+ * flag set.
  */
 struct vfio_iommu_type1_dma_unmap {
 	__u32	argsz;