[V2,33/45] vfio/iommufd: use IOMMU_IOAS_MAP_FILE

Commit Message

Steven Sistare Feb. 14, 2025, 2:14 p.m. UTC

Use IOMMU_IOAS_MAP_FILE when the mapped region is backed by a file.
Such a mapping can be preserved without modification during CPR,
because it depends on the file's address space, which does not change,
rather than on the process's address space, which does change.

Signed-off-by: Steve Sistare <[e-mail]>
---
 hw/vfio/container-base.c              |  9 +++++++++
 hw/vfio/iommufd.c                     | 13 +++++++++++++
 include/hw/vfio/vfio-container-base.h |  3 +++
 3 files changed, 25 insertions(+)

Patch

diff --git a/hw/vfio/container-base.c b/hw/vfio/container-base.c
index 302cd4c..fbaf04a 100644
--- a/hw/vfio/container-base.c
+++ b/hw/vfio/container-base.c
@@ -21,7 +21,16 @@  int vfio_container_dma_map(VFIOContainerBase *bcontainer,
                            RAMBlock *rb)
 {
     VFIOIOMMUClass *vioc = VFIO_IOMMU_GET_CLASS(bcontainer);
+    int mfd = rb ? qemu_ram_get_fd(rb) : -1;
 
+    if (mfd >= 0 && vioc->dma_map_file) {
+        unsigned long start = vaddr - qemu_ram_get_host_addr(rb);
+        unsigned long offset = qemu_ram_get_fd_offset(rb);
+
+        vioc->dma_map_file(bcontainer, iova, size, mfd, start + offset,
+                           readonly);
+        return 0;
+    }
     g_assert(vioc->dma_map);
     return vioc->dma_map(bcontainer, iova, size, vaddr, readonly);
 }
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index df61edf..ea40da5 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -38,6 +38,18 @@  static int iommufd_cdev_map(const VFIOContainerBase *bcontainer, hwaddr iova,
                                    iova, size, vaddr, readonly);
 }
 
+static int iommufd_cdev_map_file(const VFIOContainerBase *bcontainer,
+                                 hwaddr iova, ram_addr_t size,
+                                 int fd, unsigned long start, bool readonly)
+{
+    const VFIOIOMMUFDContainer *container =
+        container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
+
+    return iommufd_backend_map_file_dma(container->be,
+                                        container->ioas_id,
+                                        iova, size, fd, start, readonly);
+}
+
 static int iommufd_cdev_unmap(const VFIOContainerBase *bcontainer,
                               hwaddr iova, ram_addr_t size,
                               IOMMUTLBEntry *iotlb)
@@ -794,6 +806,7 @@  static void vfio_iommu_iommufd_class_init(ObjectClass *klass, void *data)
     vioc->hiod_typename = TYPE_HOST_IOMMU_DEVICE_IOMMUFD_VFIO;
 
     vioc->dma_map = iommufd_cdev_map;
+    vioc->dma_map_file = iommufd_cdev_map_file;
     vioc->dma_unmap = iommufd_cdev_unmap;
     vioc->attach_device = iommufd_cdev_attach;
     vioc->detach_device = iommufd_cdev_detach;
diff --git a/include/hw/vfio/vfio-container-base.h b/include/hw/vfio/vfio-container-base.h
index d82e256..4daa5f8 100644
--- a/include/hw/vfio/vfio-container-base.h
+++ b/include/hw/vfio/vfio-container-base.h
@@ -115,6 +115,9 @@  struct VFIOIOMMUClass {
     int (*dma_map)(const VFIOContainerBase *bcontainer,
                    hwaddr iova, ram_addr_t size,
                    void *vaddr, bool readonly);
+    int (*dma_map_file)(const VFIOContainerBase *bcontainer,
+                        hwaddr iova, ram_addr_t size,
+                        int fd, unsigned long start, bool readonly);
     int (*dma_unmap)(const VFIOContainerBase *bcontainer,
                      hwaddr iova, ram_addr_t size,
                      IOMMUTLBEntry *iotlb);