vfio: interfaces to update vaddr

Define interfaces that allow the underlying memory object of an iova
range to be mapped to a new host virtual address in the host process:

  - VFIO_DMA_UNMAP_FLAG_VADDR for VFIO_IOMMU_UNMAP_DMA
  - VFIO_DMA_MAP_FLAG_VADDR flag for VFIO_IOMMU_MAP_DMA
  - VFIO_UPDATE_VADDR extension for VFIO_CHECK_EXTENSION

Unmap vaddr invalidates the host virtual address in an iova range, and
blocks vfio translation of host virtual addresses.  DMA to already-mapped
pages continues.  Map vaddr updates the base VA and resumes translation.
See comments in uapi/linux/vfio.h for more details.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 78462599e5edb387beb8e1d94cced7257b19ac1e..8ce36c1d53ca119fb9a6dab82218aac0528fce56 100644 (file)
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -49,6 +49,9 @@
 /* Supports VFIO_DMA_UNMAP_FLAG_ALL */
 #define VFIO_UNMAP_ALL                 9
 
+/* Supports the vaddr flag for DMA map and unmap */
+#define VFIO_UPDATE_VADDR              10
+
 /*
  * The IOCTL interface is designed for extensibility by embedding the
  * structure length (argsz) and flags into structures passed between
@@ -1077,12 +1080,22 @@ struct vfio_iommu_type1_info_dma_avail {
  *
  * Map process virtual addresses to IO virtual addresses using the
  * provided struct vfio_dma_map. Caller sets argsz. READ &/ WRITE required.
+ *
+ * If flags & VFIO_DMA_MAP_FLAG_VADDR, update the base vaddr for iova, and
+ * unblock translation of host virtual addresses in the iova range.  The vaddr
+ * must have previously been invalidated with VFIO_DMA_UNMAP_FLAG_VADDR.  To
+ * maintain memory consistency within the user application, the updated vaddr
+ * must address the same memory object as originally mapped.  Failure to do so
+ * will result in user memory corruption and/or device misbehavior.  iova and
+ * size must match those in the original MAP_DMA call.  Protection is not
+ * changed, and the READ & WRITE flags must be 0.
  */
 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 */
+#define VFIO_DMA_MAP_FLAG_VADDR (1 << 2)
        __u64   vaddr;                          /* Process virtual address */
        __u64   iova;                           /* IO virtual address */
        __u64   size;                           /* Size of mapping (bytes) */
@@ -1118,12 +1131,18 @@ struct vfio_bitmap {
  *
  * If flags & VFIO_DMA_UNMAP_FLAG_ALL, unmap all addresses.  iova and size
  * must be 0.  This cannot be combined with the get-dirty-bitmap flag.
+ *
+ * If flags & VFIO_DMA_UNMAP_FLAG_VADDR, do not unmap, but invalidate host
+ * virtual addresses in the iova range.  Tasks that attempt to translate an
+ * iova's vaddr will block.  DMA to already-mapped pages continues.  This
+ * cannot be combined with the get-dirty-bitmap flag.
  */
 struct vfio_iommu_type1_dma_unmap {
        __u32   argsz;
        __u32   flags;
 #define VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP (1 << 0)
 #define VFIO_DMA_UNMAP_FLAG_ALL                     (1 << 1)
+#define VFIO_DMA_UNMAP_FLAG_VADDR           (1 << 2)
        __u64   iova;                           /* IO virtual address */
        __u64   size;                           /* Size of mapping (bytes) */
        __u8    data[];