[Qemu-devel] [PATCH 1/2] Implement drive_del to decouple block removal from device removal
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
---
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..c8b0206 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]",
--
1.6.3.3
Re: [Qemu-devel] [PATCH 1/2] Implement drive_del to decouple block removal from device removal
Ryan Harper writes:
> 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
> ---
> 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) {
Superfluous parenthesis around *ptr. Not worth a respin; I've tormented
you enough ;)
> +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..d6dc18c 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 delete @var{device}
> +...@findex delete
> +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]",
[Qemu-devel] [PATCH 1/2] Implement drive_del to decouple block removal from device removal
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
---
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..d6dc18c 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 delete @var{device}
+...@findex delete
+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]",
--
1.6.3.3
