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[Qemu-devel] [PATCH v2 4/6] vfio: support getting VFIOGroup from groupfd
From: |
Tiwei Bie |
Subject: |
[Qemu-devel] [PATCH v2 4/6] vfio: support getting VFIOGroup from groupfd |
Date: |
Mon, 19 Mar 2018 15:15:35 +0800 |
Add an API to support getting VFIOGroup from groupfd. When
groupfd is shared by another process, the VFIOGroup may not
have its container and address space in QEMU.
Besides, add a reference counter to better support getting
VFIOGroup multiple times.
Signed-off-by: Tiwei Bie <address@hidden>
---
hw/vfio/common.c | 97 ++++++++++++++++++++++++++++++++++++++++++-
include/hw/vfio/vfio-common.h | 2 +
2 files changed, 98 insertions(+), 1 deletion(-)
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 5e84716218..24ec0f2c8d 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1038,6 +1038,11 @@ static int vfio_connect_container(VFIOGroup *group,
AddressSpace *as,
int ret, fd;
VFIOAddressSpace *space;
+ if (as == NULL) {
+ vfio_kvm_device_add_group(group);
+ return 0;
+ }
+
space = vfio_get_address_space(as);
QLIST_FOREACH(container, &space->containers, next) {
@@ -1237,6 +1242,10 @@ static void vfio_disconnect_container(VFIOGroup *group)
{
VFIOContainer *container = group->container;
+ if (container == NULL) {
+ return;
+ }
+
QLIST_REMOVE(group, container_next);
group->container = NULL;
@@ -1275,6 +1284,86 @@ static void vfio_disconnect_container(VFIOGroup *group)
}
}
+static int vfio_groupfd_to_groupid(int groupfd)
+{
+ char linkname[PATH_MAX];
+ char pathname[PATH_MAX];
+ char *filename;
+ int groupid, len;
+
+ snprintf(linkname, sizeof(linkname), "/proc/self/fd/%d", groupfd);
+
+ len = readlink(linkname, pathname, sizeof(pathname));
+ if (len <= 0 || len >= sizeof(pathname)) {
+ return -1;
+ }
+ pathname[len] = '\0';
+
+ filename = g_path_get_basename(pathname);
+ groupid = atoi(filename);
+ g_free(filename);
+
+ return groupid;
+}
+
+/*
+ * The @as param could be NULL. In this case, groupfd is shared by
+ * another process which will setup the DMA mapping for this group,
+ * and this group won't have container and address space in QEMU.
+ */
+VFIOGroup *vfio_get_group_from_fd(int groupfd, AddressSpace *as, Error **errp)
+{
+ VFIOGroup *group;
+ int groupid;
+
+ groupid = vfio_groupfd_to_groupid(groupfd);
+ if (groupid < 0) {
+ return NULL;
+ }
+
+ QLIST_FOREACH(group, &vfio_group_list, next) {
+ if (group->groupid == groupid) {
+ /* Found it. Now is it already in the right context? */
+ if ((group->container == NULL && as == NULL) ||
+ (group->container && group->container->space->as == as)) {
+ group->refcnt++;
+ return group;
+ }
+ error_setg(errp, "group %d used in multiple address spaces",
+ group->groupid);
+ return NULL;
+ }
+ }
+
+ group = g_malloc0(sizeof(*group));
+
+ group->fd = groupfd;
+ group->groupid = groupid;
+ group->refcnt = 1;
+
+ QLIST_INIT(&group->device_list);
+
+ if (vfio_connect_container(group, as, errp)) {
+ error_prepend(errp, "failed to setup container for group %d: ",
+ groupid);
+ goto free_group_exit;
+ }
+
+ if (QLIST_EMPTY(&vfio_group_list)) {
+ qemu_register_reset(vfio_reset_handler, NULL);
+ }
+
+ QLIST_INSERT_HEAD(&vfio_group_list, group, next);
+
+ return group;
+
+free_group_exit:
+ g_free(group);
+
+ return NULL;
+}
+
+/* The @as param cannot be NULL. */
VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, Error **errp)
{
VFIOGroup *group;
@@ -1284,7 +1373,8 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as,
Error **errp)
QLIST_FOREACH(group, &vfio_group_list, next) {
if (group->groupid == groupid) {
/* Found it. Now is it already in the right context? */
- if (group->container->space->as == as) {
+ if (group->container && group->container->space->as == as) {
+ group->refcnt++;
return group;
} else {
error_setg(errp, "group %d used in multiple address spaces",
@@ -1317,6 +1407,7 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as,
Error **errp)
}
group->groupid = groupid;
+ group->refcnt = 1;
QLIST_INIT(&group->device_list);
if (vfio_connect_container(group, as, errp)) {
@@ -1348,6 +1439,10 @@ void vfio_put_group(VFIOGroup *group)
return;
}
+ if (--group->refcnt > 0) {
+ return;
+ }
+
vfio_kvm_device_del_group(group);
vfio_disconnect_container(group);
QLIST_REMOVE(group, next);
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index d9360148e6..b820f7984c 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -137,6 +137,7 @@ struct VFIODeviceOps {
typedef struct VFIOGroup {
int fd;
int groupid;
+ int refcnt;
VFIOContainer *container;
QLIST_HEAD(, VFIODevice) device_list;
QLIST_ENTRY(VFIOGroup) next;
@@ -180,6 +181,7 @@ void vfio_region_exit(VFIORegion *region);
void vfio_region_finalize(VFIORegion *region);
void vfio_reset_handler(void *opaque);
VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, Error **errp);
+VFIOGroup *vfio_get_group_from_fd(int groupfd, AddressSpace *as, Error **errp);
void vfio_put_group(VFIOGroup *group);
int vfio_get_device(VFIOGroup *group, const char *name,
VFIODevice *vbasedev, Error **errp);
--
2.11.0
- [Qemu-devel] [PATCH v2 0/6] Extend vhost-user to support VFIO based accelerators, Tiwei Bie, 2018/03/19
- [Qemu-devel] [PATCH v2 2/6] vhost-user: introduce shared vhost-user state, Tiwei Bie, 2018/03/19
- [Qemu-devel] [PATCH v2 1/6] vhost-user: support receiving file descriptors in slave_read, Tiwei Bie, 2018/03/19
- [Qemu-devel] [PATCH v2 3/6] virtio: support adding sub-regions for notify region, Tiwei Bie, 2018/03/19
- [Qemu-devel] [PATCH v2 4/6] vfio: support getting VFIOGroup from groupfd,
Tiwei Bie <=
- [Qemu-devel] [PATCH v2 5/6] vfio: remove DPRINTF() definition from vfio-common.h, Tiwei Bie, 2018/03/19
- [Qemu-devel] [PATCH v2 6/6] vhost-user: add VFIO based accelerators support, Tiwei Bie, 2018/03/19
- Re: [Qemu-devel] [PATCH v2 0/6] Extend vhost-user to support VFIO based accelerators, Michael S. Tsirkin, 2018/03/22
- Re: [Qemu-devel] [PATCH v2 0/6] Extend vhost-user to support VFIO based accelerators, Michael S. Tsirkin, 2018/03/22