From: Ryan Harper <ry...@us.ibm.com>
Currently device hotplug removal code is tied to device removal via
ACPI. All pci devices that are removable via device_del() require the
guest to respond to the request. In some cases the guest may not
respond leaving the device still accessible to the guest. The management
layer doesn't currently have a reliable way to revoke access to host
resource in the presence of an uncooperative guest.
This patch implements a new monitor command, drive_del, which
provides an explicit command to revoke access to a host block device.
drive_del first quiesces the block device (qemu_aio_flush;
bdrv_flush() and bdrv_close()). This prevents further IO from being
submitted against the host device. Finally, drive_del cleans up
pointers between the drive object (host resource) and the device
object (guest resource).
Signed-off-by: Ryan Harper <ry...@us.ibm.com>
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
blockdev.c | 39 +++++++++++++++++++++++++++++++++++++++
blockdev.h | 1 +
hmp-commands.hx | 18 ++++++++++++++++++
3 files changed, 58 insertions(+), 0 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index 6cb179a..f6ac439 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -14,6 +14,8 @@
#include "qemu-option.h"
#include "qemu-config.h"
#include "sysemu.h"
+#include "hw/qdev.h"
+#include "block_int.h"
static QTAILQ_HEAD(drivelist, DriveInfo) drives =
QTAILQ_HEAD_INITIALIZER(drives);
@@ -597,3 +599,40 @@ int do_change_block(Monitor *mon, const char *device,
}
return monitor_read_bdrv_key_start(mon, bs, NULL, NULL);
}
+
+int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
+{
+ const char *id = qdict_get_str(qdict, "id");
+ BlockDriverState *bs;
+ BlockDriverState **ptr;
+ Property *prop;
+
+ bs = bdrv_find(id);
+ if (!bs) {
+ qerror_report(QERR_DEVICE_NOT_FOUND, id);
+ return -1;
+ }
+
+ /* quiesce block driver; prevent further io */
+ qemu_aio_flush();
+ bdrv_flush(bs);
+ bdrv_close(bs);
+
+ /* clean up guest state from pointing to host resource by
+ * finding and removing DeviceState "drive" property */
+ for (prop = bs->peer->info->props; prop && prop->name; prop++) {
+ if (prop->info->type == PROP_TYPE_DRIVE) {
+ ptr = qdev_get_prop_ptr(bs->peer, prop);
+ if ((*ptr) == bs) {
+ bdrv_detach(bs, bs->peer);
+ *ptr = NULL;
+ break;
+ }
+ }
+ }
+
+ /* clean up host side */
+ drive_uninit(drive_get_by_blockdev(bs));
+
+ return 0;
+}
diff --git a/blockdev.h b/blockdev.h
index 653affc..2a0559e 100644
--- a/blockdev.h
+++ b/blockdev.h
@@ -51,5 +51,6 @@ int do_eject(Monitor *mon, const QDict *qdict, QObject
**ret_data);
int do_block_set_passwd(Monitor *mon, const QDict *qdict, QObject **ret_data);
int do_change_block(Monitor *mon, const char *device,
const char *filename, const char *fmt);
+int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
#endif
diff --git a/hmp-commands.hx b/hmp-commands.hx
index e5585ba..23024ba 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -68,6 +68,24 @@ Eject a removable medium (use -f to force it).
ETEXI
{
+ .name = "drive_del",
+ .args_type = "id:s",
+ .params = "device",
+ .help = "remove host block device",
+ .user_print = monitor_user_noop,
+ .mhandler.cmd_new = do_drive_del,
+ },
+
+STEXI
+...@item drive_del @var{device}
+...@findex drive_del
+Remove host block device. The result is that guest generated IO is no longer
+submitted against the host device underlying the disk. Once a drive has
+been deleted, the QEMU Block layer returns -EIO which results in IO
+errors in the guest for applications that are reading/writing to the device.
+ETEXI
+
+ {
.name = "change",
.args_type = "device:B,target:F,arg:s?",
.params = "device filename [format]",
--
1.7.2.3
