Re: [Qemu-devel] [PATCH 2/2] virtio-scsi: Implement hotplug support for virtio-scsi
Quoting Stefan Hajnoczi stefa...@gmail.com: On Wed, Jun 20, 2012 at 7:47 AM, Cong Meng m...@linux.vnet.ibm.com wrote: Implement the hotplug() and hot_unplug() interfaces in virtio-scsi, by signal the virtio_scsi.ko in guest kernel via event virtual queue. The counterpart patch of virtio_scsi.ko will be sent soon in another thread. Signed-off-by: Cong Meng m...@linux.vnet.ibm.com Signed-off-by: Sen Wang senw...@linux.vnet.ibm.com --- hw/virtio-scsi.c | 72 +++-- 1 files changed, 69 insertions(+), 3 deletions(-) I compared against the virtio-scsi specification and this looks good: http://ozlabs.org/~rusty/virtio-spec/virtio-0.9.5.pdf Dropped events and event throttling are not implemented by this patch. This means that the guest can miss events if it runs out of event queue elements. A scenario that might be able to trigger this is if multiple LUNs are hotplugged in a single QEMU monitor callback. Implementing dropped events is easy in hw/virtio-scsi.c. Keep a bool or counter of dropped events and report them when the guest kicks us with a free event element (virtio_scsi_handle_event). Yes. It's easy to do this in qemu. But I'm not sure what should be done in virtio-scsi.ko to respond the VIRTIO_SCSI_T_EVENTS_MISSED event. The spec says poll the logical units for unit attention conditions, or just a whole bus rescan? Stefan
Re: [Qemu-devel] [PATCH 2/2] virtio-scsi: Implement hotplug support for virtio-scsi
On Mon, Jun 25, 2012 at 03:51:13AM -0400, m...@linux.vnet.ibm.com wrote: Quoting Stefan Hajnoczi stefa...@gmail.com: On Wed, Jun 20, 2012 at 7:47 AM, Cong Meng m...@linux.vnet.ibm.com wrote: Implement the hotplug() and hot_unplug() interfaces in virtio-scsi, by signal the virtio_scsi.ko in guest kernel via event virtual queue. The counterpart patch of virtio_scsi.ko will be sent soon in another thread. Signed-off-by: Cong Meng m...@linux.vnet.ibm.com Signed-off-by: Sen Wang senw...@linux.vnet.ibm.com --- hw/virtio-scsi.c | 72 +++-- 1 files changed, 69 insertions(+), 3 deletions(-) I compared against the virtio-scsi specification and this looks good: http://ozlabs.org/~rusty/virtio-spec/virtio-0.9.5.pdf Dropped events and event throttling are not implemented by this patch. This means that the guest can miss events if it runs out of event queue elements. A scenario that might be able to trigger this is if multiple LUNs are hotplugged in a single QEMU monitor callback. Implementing dropped events is easy in hw/virtio-scsi.c. Keep a bool or counter of dropped events and report them when the guest kicks us with a free event element (virtio_scsi_handle_event). Yes. It's easy to do this in qemu. But I'm not sure what should be done in virtio-scsi.ko to respond the VIRTIO_SCSI_T_EVENTS_MISSED event. The spec says poll the logical units for unit attention conditions, or just a whole bus rescan? I'm not sure what the answer is either, maybe you can find an existing SCSI LLD that does what you need. Stefan
Re: [Qemu-devel] [PATCH 2/2] virtio-scsi: Implement hotplug support for virtio-scsi
On Wed, Jun 20, 2012 at 7:47 AM, Cong Meng m...@linux.vnet.ibm.com wrote: Implement the hotplug() and hot_unplug() interfaces in virtio-scsi, by signal the virtio_scsi.ko in guest kernel via event virtual queue. The counterpart patch of virtio_scsi.ko will be sent soon in another thread. Signed-off-by: Cong Meng m...@linux.vnet.ibm.com Signed-off-by: Sen Wang senw...@linux.vnet.ibm.com --- hw/virtio-scsi.c | 72 +++-- 1 files changed, 69 insertions(+), 3 deletions(-) I compared against the virtio-scsi specification and this looks good: http://ozlabs.org/~rusty/virtio-spec/virtio-0.9.5.pdf Dropped events and event throttling are not implemented by this patch. This means that the guest can miss events if it runs out of event queue elements. A scenario that might be able to trigger this is if multiple LUNs are hotplugged in a single QEMU monitor callback. Implementing dropped events is easy in hw/virtio-scsi.c. Keep a bool or counter of dropped events and report them when the guest kicks us with a free event element (virtio_scsi_handle_event). Stefan
[Qemu-devel] [PATCH 2/2] virtio-scsi: Implement hotplug support for virtio-scsi
Implement the hotplug() and hot_unplug() interfaces in virtio-scsi, by signal
the virtio_scsi.ko in guest kernel via event virtual queue.
The counterpart patch of virtio_scsi.ko will be sent soon in another thread.
Signed-off-by: Cong Meng m...@linux.vnet.ibm.com
Signed-off-by: Sen Wang senw...@linux.vnet.ibm.com
---
hw/virtio-scsi.c | 72 +++--
1 files changed, 69 insertions(+), 3 deletions(-)
diff --git a/hw/virtio-scsi.c b/hw/virtio-scsi.c
index e8328f4..626ec5f 100644
--- a/hw/virtio-scsi.c
+++ b/hw/virtio-scsi.c
@@ -24,6 +24,10 @@
#define VIRTIO_SCSI_MAX_TARGET 255
#define VIRTIO_SCSI_MAX_LUN 16383
+/* Feature Bits */
+#define VIRTIO_SCSI_F_INOUT0
+#define VIRTIO_SCSI_F_HOTPLUG 1
+
/* Response codes */
#define VIRTIO_SCSI_S_OK 0
#define VIRTIO_SCSI_S_OVERRUN 1
@@ -60,6 +64,11 @@
#define VIRTIO_SCSI_T_TRANSPORT_RESET 1
#define VIRTIO_SCSI_T_ASYNC_NOTIFY 2
+/* Reasons of transport reset event */
+#define VIRTIO_SCSI_EVT_RESET_HARD 0
+#define VIRTIO_SCSI_EVT_RESET_RESCAN 1
+#define VIRTIO_SCSI_EVT_RESET_REMOVED 2
+
/* SCSI command request, followed by data-out */
typedef struct {
uint8_t lun[8]; /* Logical Unit Number */
@@ -206,11 +215,12 @@ static void qemu_sgl_init_external(QEMUSGList *qsgl,
struct iovec *sg,
static void virtio_scsi_parse_req(VirtIOSCSI *s, VirtQueue *vq,
VirtIOSCSIReq *req)
{
-assert(req-elem.out_num req-elem.in_num);
+assert(req-elem.in_num);
req-vq = vq;
req-dev = s;
req-sreq = NULL;
-req-req.buf = req-elem.out_sg[0].iov_base;
+if (req-elem.out_num)
+req-req.buf = req-elem.out_sg[0].iov_base;
req-resp.buf = req-elem.in_sg[0].iov_base;
if (req-elem.out_num 1) {
@@ -405,6 +415,10 @@ static void virtio_scsi_handle_ctrl(VirtIODevice *vdev,
VirtQueue *vq)
}
}
+static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq)
+{
+}
+
static void virtio_scsi_command_complete(SCSIRequest *r, uint32_t status,
size_t resid)
{
@@ -541,6 +555,7 @@ static void virtio_scsi_set_config(VirtIODevice *vdev,
static uint32_t virtio_scsi_get_features(VirtIODevice *vdev,
uint32_t requested_features)
{
+requested_features |= (1UL VIRTIO_SCSI_F_HOTPLUG);
return requested_features;
}
@@ -568,6 +583,55 @@ static int virtio_scsi_load(QEMUFile *f, void *opaque, int
version_id)
return 0;
}
+static void virtio_scsi_push_event(VirtIOSCSI *s, uint32_t target, uint32_t
lun,
+ uint32_t event, uint32_t reason)
+{
+VirtIOSCSIReq *req;
+VirtIOSCSIEvent *evt;
+
+if ((req = virtio_scsi_pop_req(s, s-event_vq))) {
+int in_size;
+if (req-elem.out_num || req-elem.in_num != 1) {
+virtio_scsi_bad_req();
+}
+
+in_size = req-elem.in_sg[0].iov_len;
+if (in_size sizeof(VirtIOSCSIEvent)) {
+virtio_scsi_bad_req();
+}
+
+evt = req-resp.event;
+evt-event = event;
+evt-reason = reason;
+evt-lun[0] = 0;
+evt-lun[1] = target;
+evt-lun[2] = (lun 8);
+evt-lun[3] = lun 0xFF;
+virtio_scsi_complete_req(req);
+}
+}
+
+static void virtio_scsi_hotplug(SCSIBus *bus, SCSIDevice *dev)
+{
+VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
+
+if (((s-vdev.guest_features VIRTIO_SCSI_F_HOTPLUG) 1)
+(s-vdev.status VIRTIO_CONFIG_S_DRIVER_OK)) {
+virtio_scsi_push_event(s, dev-id, dev-lun,
+VIRTIO_SCSI_T_TRANSPORT_RESET, VIRTIO_SCSI_EVT_RESET_RESCAN);
+}
+}
+
+static void virtio_scsi_hot_unplug(SCSIBus *bus, SCSIDevice *dev)
+{
+VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
+
+if ((s-vdev.guest_features VIRTIO_SCSI_F_HOTPLUG) 1) {
+virtio_scsi_push_event(s, dev-id, dev-lun,
+VIRTIO_SCSI_T_TRANSPORT_RESET, VIRTIO_SCSI_EVT_RESET_REMOVED);
+}
+}
+
static struct SCSIBusInfo virtio_scsi_scsi_info = {
.tcq = true,
.max_channel = VIRTIO_SCSI_MAX_CHANNEL,
@@ -576,6 +640,8 @@ static struct SCSIBusInfo virtio_scsi_scsi_info = {
.complete = virtio_scsi_command_complete,
.cancel = virtio_scsi_request_cancelled,
+.hotplug = virtio_scsi_hotplug,
+.hot_unplug = virtio_scsi_hot_unplug,
.get_sg_list = virtio_scsi_get_sg_list,
.save_request = virtio_scsi_save_request,
.load_request = virtio_scsi_load_request,
@@ -604,7 +670,7 @@ VirtIODevice *virtio_scsi_init(DeviceState *dev,
VirtIOSCSIConf *proxyconf)
s-ctrl_vq = virtio_add_queue(s-vdev, VIRTIO_SCSI_VQ_SIZE,
virtio_scsi_handle_ctrl);
s-event_vq = virtio_add_queue(s-vdev, VIRTIO_SCSI_VQ_SIZE,
-
