RE: [PATCH v5 08/13] vfio/{iommufd,container}: Invoke HostIOMMUDevice::realize() during attach_device()

[Duan, Zhenzhong]

>-----Original Message-----
>From: Joao Martins <joao.m.martins@oracle.com>
>Subject: [PATCH v5 08/13] vfio/{iommufd,container}: Invoke
>HostIOMMUDevice::realize() during attach_device()
>
>Move the HostIOMMUDevice::realize() to be invoked during the attach of
>the device
>before we allocate IOMMUFD hardware pagetable objects (HWPT). This
>allows the use
>of the hw_caps obtained by IOMMU_GET_HW_INFO that essentially tell if
>the IOMMU
>behind the device supports dirty tracking.
>
>Note: The HostIOMMUDevice data from legacy backend is static and doesn't
>need any information from the (type1-iommu) backend to be initialized.
>In contrast however, the IOMMUFD HostIOMMUDevice data requires the
>iommufd FD to be connected and having a devid to be able to successfully
>GET_HW_INFO. This means vfio_device_hiod_realize() is called in
>different places within the backend .attach_device() implementation.
>
>Suggested-by: Cédric Le Goater <clg@redhat.cm>
>Signed-off-by: Joao Martins <joao.m.martins@oracle.com>

Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

Thanks
Zhenzhong

>---
> include/hw/vfio/vfio-common.h |  1 +
> hw/vfio/common.c              | 16 ++++++----------
> hw/vfio/container.c           |  4 ++++
> hw/vfio/helpers.c             | 11 +++++++++++
> hw/vfio/iommufd.c             |  4 ++++
> 5 files changed, 26 insertions(+), 10 deletions(-)
>
>diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-
>common.h
>index 1a96678f8c38..4e44b26d3c45 100644
>--- a/include/hw/vfio/vfio-common.h
>+++ b/include/hw/vfio/vfio-common.h
>@@ -242,6 +242,7 @@ void vfio_region_finalize(VFIORegion *region);
> void vfio_reset_handler(void *opaque);
> struct vfio_device_info *vfio_get_device_info(int fd);
> bool vfio_device_is_mdev(VFIODevice *vbasedev);
>+bool vfio_device_hiod_realize(VFIODevice *vbasedev, Error **errp);
> bool vfio_attach_device(char *name, VFIODevice *vbasedev,
>                         AddressSpace *as, Error **errp);
> void vfio_detach_device(VFIODevice *vbasedev);
>diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>index b0beed44116e..cc14f0e3fe24 100644
>--- a/hw/vfio/common.c
>+++ b/hw/vfio/common.c
>@@ -1544,7 +1544,7 @@ bool vfio_attach_device(char *name, VFIODevice
>*vbasedev,
> {
>     const VFIOIOMMUClass *ops =
>
>VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_LEGACY));
>-    HostIOMMUDevice *hiod;
>+    HostIOMMUDevice *hiod = NULL;
>
>     if (vbasedev->iommufd) {
>         ops =
>VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_IOMMUF
>D));
>@@ -1552,21 +1552,17 @@ bool vfio_attach_device(char *name,
>VFIODevice *vbasedev,
>
>     assert(ops);
>
>-    if (!ops->attach_device(name, vbasedev, as, errp)) {
>-        return false;
>-    }
>
>-    if (vbasedev->mdev) {
>-        return true;
>+    if (!vbasedev->mdev) {
>+        hiod = HOST_IOMMU_DEVICE(object_new(ops->hiod_typename));
>+        vbasedev->hiod = hiod;
>     }
>
>-    hiod = HOST_IOMMU_DEVICE(object_new(ops->hiod_typename));
>-    if (!HOST_IOMMU_DEVICE_GET_CLASS(hiod)->realize(hiod, vbasedev,
>errp)) {
>+    if (!ops->attach_device(name, vbasedev, as, errp)) {
>         object_unref(hiod);
>-        ops->detach_device(vbasedev);
>+        vbasedev->hiod = NULL;
>         return false;
>     }
>-    vbasedev->hiod = hiod;
>
>     return true;
> }
>diff --git a/hw/vfio/container.c b/hw/vfio/container.c
>index c27f448ba26e..adb302216e23 100644
>--- a/hw/vfio/container.c
>+++ b/hw/vfio/container.c
>@@ -917,6 +917,10 @@ static bool vfio_legacy_attach_device(const char
>*name, VFIODevice *vbasedev,
>
>     trace_vfio_attach_device(vbasedev->name, groupid);
>
>+    if (!vfio_device_hiod_realize(vbasedev, errp)) {
>+        return false;
>+    }
>+
>     group = vfio_get_group(groupid, as, errp);
>     if (!group) {
>         return false;
>diff --git a/hw/vfio/helpers.c b/hw/vfio/helpers.c
>index 7e23e9080c9d..ea15c79db0a3 100644
>--- a/hw/vfio/helpers.c
>+++ b/hw/vfio/helpers.c
>@@ -689,3 +689,14 @@ bool vfio_device_is_mdev(VFIODevice *vbasedev)
>     subsys = realpath(tmp, NULL);
>     return subsys && (strcmp(subsys, "/sys/bus/mdev") == 0);
> }
>+
>+bool vfio_device_hiod_realize(VFIODevice *vbasedev, Error **errp)
>+{
>+    HostIOMMUDevice *hiod = vbasedev->hiod;
>+
>+    if (!hiod) {
>+        return true;
>+    }
>+
>+    return HOST_IOMMU_DEVICE_GET_CLASS(hiod)->realize(hiod, vbasedev,
>errp);
>+}
>diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
>index 7a10b1e90a6f..bb44d948c735 100644
>--- a/hw/vfio/iommufd.c
>+++ b/hw/vfio/iommufd.c
>@@ -403,6 +403,10 @@ static bool iommufd_cdev_attach(const char
>*name, VFIODevice *vbasedev,
>
>     space = vfio_get_address_space(as);
>
>+    if (!vfio_device_hiod_realize(vbasedev, errp)) {
>+        return false;
>+    }
>+
>     /* try to attach to an existing container in this space */
>     QLIST_FOREACH(bcontainer, &space->containers, next) {
>         container = container_of(bcontainer, VFIOIOMMUFDContainer,
>bcontainer);
>--
>2.17.2