| Message ID | 147487889679.6679.15125059315439240946.stgit@bahia |
|---|---|
| State | New |
| Headers | show |
On Mon, Sep 26, 2016 at 10:34:56AM +0200, Greg Kurz wrote: > The virtio_scsi_bad_req() function is called when a guest sends a > request with missing or ill-sized headers. This generally happens > when the virtio_scsi_parse_req() function returns an error. > > With this patch, virtio_scsi_bad_req() will mark the device as broken, > detach the request from the virtqueue and free it, instead of forcing > QEMU to exit. > > In nearly all locations where virtio_scsi_bad_req() is called, the only > thing to do next is to return to the caller. > > The virtio_scsi_handle_cmd_req_prepare() function is an exception though. > > It is called in a loop by virtio_scsi_handle_cmd_vq() and passed requests > freshly popped from a cmd virtqueue; virtio_scsi_handle_cmd_req_prepare() > does some sanity checks on the request and returns a boolean flag to > indicate whether the request should be queued or not. In the latter case, > virtio_scsi_handle_cmd_req_prepare() has detected a non-fatal error and > sent a response back to the guest. > > We have now a new condition to take into account: the device is broken > and should stop all processing. > > The return value of virtio_scsi_handle_cmd_req_prepare() is hence changed > to an int. A return value of zero means that the request should be queued. > Other non-fatal error cases where the reqyest shoudn't be queued return s/reqyest/request/ > @@ -574,11 +578,24 @@ static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req) > void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > { > VirtIOSCSIReq *req, *next; > + int ret; > + > QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs); > > while ((req = virtio_scsi_pop_req(s, vq))) { > - if (virtio_scsi_handle_cmd_req_prepare(s, req)) { > + ret = virtio_scsi_handle_cmd_req_prepare(s, req); > + if (!ret) { > QTAILQ_INSERT_TAIL(&reqs, req, next); > + } else if (ret == -EINVAL) { > + /* The device is broken and shouldn't process any request */ > + while (!QTAILQ_EMPTY(&reqs)) { > + req = QTAILQ_FIRST(&reqs); > + QTAILQ_REMOVE(&reqs, req, next); > + blk_io_unplug(req->sreq->dev->conf.blk); Are you sure blk_io_plug() was called for this request? If we returned early in virtio_scsi_handle_cmd_req_prepare() then it wasn't called. > + scsi_req_unref(req->sreq); Which scsi_req_ref() is this paired with? If it's the call in scsi_req_enqueue() then that function was never called and we shouldn't unref.
On Mon, 26 Sep 2016 17:35:38 +0100 Stefan Hajnoczi <stefanha@redhat.com> wrote: > On Mon, Sep 26, 2016 at 10:34:56AM +0200, Greg Kurz wrote: > > The virtio_scsi_bad_req() function is called when a guest sends a > > request with missing or ill-sized headers. This generally happens > > when the virtio_scsi_parse_req() function returns an error. > > > > With this patch, virtio_scsi_bad_req() will mark the device as broken, > > detach the request from the virtqueue and free it, instead of forcing > > QEMU to exit. > > > > In nearly all locations where virtio_scsi_bad_req() is called, the only > > thing to do next is to return to the caller. > > > > The virtio_scsi_handle_cmd_req_prepare() function is an exception though. > > > > It is called in a loop by virtio_scsi_handle_cmd_vq() and passed requests > > freshly popped from a cmd virtqueue; virtio_scsi_handle_cmd_req_prepare() > > does some sanity checks on the request and returns a boolean flag to > > indicate whether the request should be queued or not. In the latter case, > > virtio_scsi_handle_cmd_req_prepare() has detected a non-fatal error and > > sent a response back to the guest. > > > > We have now a new condition to take into account: the device is broken > > and should stop all processing. > > > > The return value of virtio_scsi_handle_cmd_req_prepare() is hence changed > > to an int. A return value of zero means that the request should be queued. > > Other non-fatal error cases where the reqyest shoudn't be queued return > > s/reqyest/request/ > oops... > > @@ -574,11 +578,24 @@ static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req) > > void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > > { > > VirtIOSCSIReq *req, *next; > > + int ret; > > + > > QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs); > > > > while ((req = virtio_scsi_pop_req(s, vq))) { > > - if (virtio_scsi_handle_cmd_req_prepare(s, req)) { > > + ret = virtio_scsi_handle_cmd_req_prepare(s, req); > > + if (!ret) { > > QTAILQ_INSERT_TAIL(&reqs, req, next); > > + } else if (ret == -EINVAL) { > > + /* The device is broken and shouldn't process any request */ > > + while (!QTAILQ_EMPTY(&reqs)) { > > + req = QTAILQ_FIRST(&reqs); > > + QTAILQ_REMOVE(&reqs, req, next); > > + blk_io_unplug(req->sreq->dev->conf.blk); > > Are you sure blk_io_plug() was called for this request? If we returned > early in virtio_scsi_handle_cmd_req_prepare() then it wasn't called. > Early return in virtio_scsi_handle_cmd_req_prepare() means an error was detected, in which case the request didn't get queued; we are sure that blk_io_plug() was called for all requests in this queue. > > + scsi_req_unref(req->sreq); > > Which scsi_req_ref() is this paired with? If it's the call in > scsi_req_enqueue() then that function was never called and we shouldn't > unref. It is paired with the one in virtio_scsi_handle_cmd_req_prepare(), which is called just before blk_io_plug(). But looking at the patch again, I realize I missed this: @@ -562,7 +562,7 @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, } scsi_req_ref(req->sreq); blk_io_plug(d->conf.blk); - return true; + return 0; } static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req I'll send a v4. Cheers. -- Greg
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index e596b6474131..fca23185a7fd 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -81,10 +81,11 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req) virtio_scsi_free_req(req); } -static void virtio_scsi_bad_req(void) +static void virtio_scsi_bad_req(VirtIOSCSIReq *req) { - error_report("wrong size for virtio-scsi headers"); - exit(1); + virtio_error(VIRTIO_DEVICE(req->dev), "wrong size for virtio-scsi headers"); + virtqueue_detach_element(req->vq, &req->elem, 0); + virtio_scsi_free_req(req); } static size_t qemu_sgl_concat(VirtIOSCSIReq *req, struct iovec *iov, @@ -387,7 +388,7 @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req) if (iov_to_buf(req->elem.out_sg, req->elem.out_num, 0, &type, sizeof(type)) < sizeof(type)) { - virtio_scsi_bad_req(); + virtio_scsi_bad_req(req); return; } @@ -395,7 +396,8 @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req) if (type == VIRTIO_SCSI_T_TMF) { if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlTMFReq), sizeof(VirtIOSCSICtrlTMFResp)) < 0) { - virtio_scsi_bad_req(); + virtio_scsi_bad_req(req); + return; } else { r = virtio_scsi_do_tmf(s, req); } @@ -404,7 +406,8 @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req) type == VIRTIO_SCSI_T_AN_SUBSCRIBE) { if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlANReq), sizeof(VirtIOSCSICtrlANResp)) < 0) { - virtio_scsi_bad_req(); + virtio_scsi_bad_req(req); + return; } else { req->resp.an.event_actual = 0; req->resp.an.response = VIRTIO_SCSI_S_OK; @@ -521,7 +524,7 @@ static void virtio_scsi_fail_cmd_req(VirtIOSCSIReq *req) virtio_scsi_complete_cmd_req(req); } -static bool virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req) +static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req) { VirtIOSCSICommon *vs = &s->parent_obj; SCSIDevice *d; @@ -532,17 +535,18 @@ static bool virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req if (rc < 0) { if (rc == -ENOTSUP) { virtio_scsi_fail_cmd_req(req); + return -ENOTSUP; } else { - virtio_scsi_bad_req(); + virtio_scsi_bad_req(req); + return -EINVAL; } - return false; } d = virtio_scsi_device_find(s, req->req.cmd.lun); if (!d) { req->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET; virtio_scsi_complete_cmd_req(req); - return false; + return -ENOENT; } virtio_scsi_ctx_check(s, d); req->sreq = scsi_req_new(d, req->req.cmd.tag, @@ -554,7 +558,7 @@ static bool virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req req->sreq->cmd.xfer > req->qsgl.size)) { req->resp.cmd.response = VIRTIO_SCSI_S_OVERRUN; virtio_scsi_complete_cmd_req(req); - return false; + return -ENOBUFS; } scsi_req_ref(req->sreq); blk_io_plug(d->conf.blk); @@ -574,11 +578,24 @@ static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req) void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) { VirtIOSCSIReq *req, *next; + int ret; + QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs); while ((req = virtio_scsi_pop_req(s, vq))) { - if (virtio_scsi_handle_cmd_req_prepare(s, req)) { + ret = virtio_scsi_handle_cmd_req_prepare(s, req); + if (!ret) { QTAILQ_INSERT_TAIL(&reqs, req, next); + } else if (ret == -EINVAL) { + /* The device is broken and shouldn't process any request */ + while (!QTAILQ_EMPTY(&reqs)) { + req = QTAILQ_FIRST(&reqs); + QTAILQ_REMOVE(&reqs, req, next); + blk_io_unplug(req->sreq->dev->conf.blk); + scsi_req_unref(req->sreq); + virtqueue_detach_element(req->vq, &req->elem, 0); + virtio_scsi_free_req(req); + } } } @@ -708,7 +725,8 @@ void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev, } if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) { - virtio_scsi_bad_req(); + virtio_scsi_bad_req(req); + goto out; } evt = &req->resp.event;
The virtio_scsi_bad_req() function is called when a guest sends a request with missing or ill-sized headers. This generally happens when the virtio_scsi_parse_req() function returns an error. With this patch, virtio_scsi_bad_req() will mark the device as broken, detach the request from the virtqueue and free it, instead of forcing QEMU to exit. In nearly all locations where virtio_scsi_bad_req() is called, the only thing to do next is to return to the caller. The virtio_scsi_handle_cmd_req_prepare() function is an exception though. It is called in a loop by virtio_scsi_handle_cmd_vq() and passed requests freshly popped from a cmd virtqueue; virtio_scsi_handle_cmd_req_prepare() does some sanity checks on the request and returns a boolean flag to indicate whether the request should be queued or not. In the latter case, virtio_scsi_handle_cmd_req_prepare() has detected a non-fatal error and sent a response back to the guest. We have now a new condition to take into account: the device is broken and should stop all processing. The return value of virtio_scsi_handle_cmd_req_prepare() is hence changed to an int. A return value of zero means that the request should be queued. Other non-fatal error cases where the reqyest shoudn't be queued return a negative errno (values are vaguely inspired by the error condition, but the only goal here is to discriminate the case we're interested in). And finally, if virtio_scsi_bad_req() was called, -EINVAL is returned. In this case, virtio_scsi_handle_cmd_vq() detaches and frees already queued requests, instead of submitting them. Signed-off-by: Greg Kurz <groug@kaod.org> --- v3: - detach and free element in virtio_scsi_bad_req() - detach and free all queued requests in virtio_scsi_handle_cmd_vq() - updated changelog --- hw/scsi/virtio-scsi.c | 44 +++++++++++++++++++++++++++++++------------- 1 file changed, 31 insertions(+), 13 deletions(-)