[PATCH v4 07/12] vfio/{iommufd, container}: Initialize HostIOMMUDeviceCaps during attach_device()

[Joao Martins]

Fetch IOMMU hw raw caps behind the device and thus move the
HostIOMMUDevice::realize() to be done during the attach of the device. It
allows it to cache the information obtained from IOMMU_GET_HW_INFO from
iommufd early on. However, while legacy HostIOMMUDevice caps
always return true and doesn't have dependency on other things, the IOMMUFD
backend requires the iommufd FD to be connected and having a devid to be
able to query capabilities. Hence when exactly is HostIOMMUDevice
initialized inside backend ::attach_device() implementation is backend
specific.

This is in preparation to fetch parse hw capabilities and understand if
dirty tracking is supported by device backing IOMMU without necessarily
duplicating the amount of calls we do to IOMMU_GET_HW_INFO.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 include/sysemu/host_iommu_device.h |  1 +
 hw/vfio/common.c                   | 16 ++++++----------
 hw/vfio/container.c                |  6 ++++++
 hw/vfio/iommufd.c                  |  7 +++++++
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/include/sysemu/host_iommu_device.h 
b/include/sysemu/host_iommu_device.h
index 20e77cf54568..b1e5f4b8ac3e 100644
--- a/include/sysemu/host_iommu_device.h
+++ b/include/sysemu/host_iommu_device.h
@@ -24,6 +24,7 @@
  */
 typedef struct HostIOMMUDeviceCaps {
     uint32_t type;
+    uint64_t hw_caps;
 } HostIOMMUDeviceCaps;
 
 #define TYPE_HOST_IOMMU_DEVICE "host-iommu-device"
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_IOMMUFD));
@@ -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..29da261bbf3e 100644
--- a/hw/vfio/container.c
+++ b/hw/vfio/container.c
@@ -907,6 +907,7 @@ static bool vfio_legacy_attach_device(const char *name, 
VFIODevice *vbasedev,
                                       AddressSpace *as, Error **errp)
 {
     int groupid = vfio_device_groupid(vbasedev, errp);
+    HostIOMMUDevice *hiod = vbasedev->hiod;
     VFIODevice *vbasedev_iter;
     VFIOGroup *group;
     VFIOContainerBase *bcontainer;
@@ -917,6 +918,11 @@ static bool vfio_legacy_attach_device(const char *name, 
VFIODevice *vbasedev,
 
     trace_vfio_attach_device(vbasedev->name, groupid);
 
+    if (hiod &&
+        !HOST_IOMMU_DEVICE_GET_CLASS(hiod)->realize(hiod, vbasedev, errp)) {
+        return false;
+    }
+
     group = vfio_get_group(groupid, as, errp);
     if (!group) {
         return false;
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 873c919e319c..d34dc88231ec 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -384,6 +384,7 @@ static bool iommufd_cdev_attach(const char *name, 
VFIODevice *vbasedev,
     Error *err = NULL;
     const VFIOIOMMUClass *iommufd_vioc =
         VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_IOMMUFD));
+    HostIOMMUDevice *hiod = vbasedev->hiod;
 
     if (vbasedev->fd < 0) {
         devfd = iommufd_cdev_getfd(vbasedev->sysfsdev, errp);
@@ -401,6 +402,11 @@ static bool iommufd_cdev_attach(const char *name, 
VFIODevice *vbasedev,
 
     space = vfio_get_address_space(as);
 
+    if (hiod &&
+        !HOST_IOMMU_DEVICE_GET_CLASS(hiod)->realize(hiod, 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);
@@ -722,6 +728,7 @@ static bool hiod_iommufd_vfio_realize(HostIOMMUDevice 
*hiod, void *opaque,
 
     hiod->name = g_strdup(vdev->name);
     caps->type = type;
+    caps->hw_caps = hw_caps;
 
     return true;
 }
-- 
2.17.2