RE: [PATCH V3 31/42] vfio/iommufd: use IOMMU_IOAS_MAP_FILE

[Duan, Zhenzhong]

>-----Original Message-----
>From: Steve Sistare <steven.sistare@oracle.com>
>Subject: [PATCH V3 31/42] vfio/iommufd: use IOMMU_IOAS_MAP_FILE
>
>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 <steven.sistare@oracle.com>
>---
> hw/vfio/container-base.c              |  9 +++++++++
> hw/vfio/iommufd.c                     | 13 +++++++++++++
> include/hw/vfio/vfio-container-base.h |  3 +++
> 3 files changed, 25 insertions(+)
>
>diff --git a/hw/vfio/container-base.c b/hw/vfio/container-base.c
>index 8f43bc8..72a51a6 100644
>--- a/hw/vfio/container-base.c
>+++ b/hw/vfio/container-base.c
>@@ -79,7 +79,16 @@ 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);

Shouldn't we return result to call site?

>+        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 167bda4..6eb417a 100644
>--- a/hw/vfio/iommufd.c
>+++ b/hw/vfio/iommufd.c
>@@ -44,6 +44,18 @@ 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, bool unmap_all)
>@@ -802,6 +814,7 @@ static void vfio_iommu_iommufd_class_init(ObjectClass
>*klass, const void *data)
>     VFIOIOMMUClass *vioc = VFIO_IOMMU_CLASS(klass);
>
>     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 03b3f9c..f30f828 100644
>--- a/include/hw/vfio/vfio-container-base.h
>+++ b/include/hw/vfio/vfio-container-base.h
>@@ -123,6 +123,9 @@ 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);
>     /**
>      * @dma_unmap
>      *
>--
>1.8.3.1