Message ID | 69a1a349ba21144e66843ab335cb3a243926bba8.1340022196.git.mc@linux.vnet.ibm.com |
---|---|
State | New |
Headers | show |
On Wed, Jun 20, 2012 at 7:47 AM, Cong Meng <mc@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 <mc@linux.vnet.ibm.com> > Signed-off-by: Sen Wang <senwang@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
Quoting Stefan Hajnoczi <stefanha@gmail.com>: > On Wed, Jun 20, 2012 at 7:47 AM, Cong Meng <mc@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 <mc@linux.vnet.ibm.com> >> Signed-off-by: Sen Wang <senwang@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
On Mon, Jun 25, 2012 at 03:51:13AM -0400, mc@linux.vnet.ibm.com wrote: > > Quoting Stefan Hajnoczi <stefanha@gmail.com>: > > >On Wed, Jun 20, 2012 at 7:47 AM, Cong Meng <mc@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 <mc@linux.vnet.ibm.com> > >>Signed-off-by: Sen Wang <senwang@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
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_INOUT 0 +#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, - NULL); + virtio_scsi_handle_event); for (i = 0; i < s->conf->num_queues; i++) { s->cmd_vqs[i] = virtio_add_queue(&s->vdev, VIRTIO_SCSI_VQ_SIZE, virtio_scsi_handle_cmd);