| Message ID | 1430137765-13771-1-git-send-email-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Apr 27, 2015 at 02:29:25PM +0200, Paolo Bonzini wrote: > qsgl->size is the size of the data field after the request or > response header (virtio-scsi currently supports only one such > field; bidirectional requests are not supported). However, > the used ring's len field is not concerned about the field > after the request header, so do not count it unless req->mode > signals the request was a read. > > Also, do not report that anything was written if the request > failed, and subtract any residual bytes in case of buffer underrun. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Pls merge through the storage tree. Also, can you pls fix up blk similarly? > --- > hw/scsi/virtio-scsi.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c > index c9bea06..4995f6e 100644 > --- a/hw/scsi/virtio-scsi.c > +++ b/hw/scsi/virtio-scsi.c > @@ -65,6 +65,19 @@ void virtio_scsi_free_req(VirtIOSCSIReq *req) > g_slice_free1(sizeof(*req) + vs->cdb_size, req); > } > > +static size_t virtio_scsi_written_length(VirtIODevice *vdev, VirtIOSCSIReq *req) > +{ > + size_t sz = req->resp_iov.size; > + > + if (req->sreq && > + req->mode == SCSI_XFER_FROM_DEV && > + req->resp.cmd.response == VIRTIO_SCSI_S_OK) { > + sz += req->qsgl.size - virtio_tswap32(vdev, req->resp.cmd.resid); > + } > + > + return sz; > +} > + > static void virtio_scsi_complete_req(VirtIOSCSIReq *req) > { > VirtIOSCSI *s = req->dev; > @@ -76,7 +89,7 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req) > assert(req->vq == NULL); > virtio_scsi_vring_push_notify(req); > } else { > - virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size); > + virtqueue_push(vq, &req->elem, virtio_scsi_written_length(vdev, req)); > virtio_notify(vdev, vq); > } > > -- > 2.3.5
On 27/04/2015 15:23, Michael S. Tsirkin wrote: > On Mon, Apr 27, 2015 at 02:29:25PM +0200, Paolo Bonzini wrote: >> > qsgl->size is the size of the data field after the request or >> > response header (virtio-scsi currently supports only one such >> > field; bidirectional requests are not supported). However, >> > the used ring's len field is not concerned about the field >> > after the request header, so do not count it unless req->mode >> > signals the request was a read. >> > >> > Also, do not report that anything was written if the request >> > failed, and subtract any residual bytes in case of buffer underrun. >> > >> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > Acked-by: Michael S. Tsirkin <mst@redhat.com> > > Pls merge through the storage tree. Ok, I'll take it through the SCSI tree then. > Also, can you pls fix up blk similarly? Because virtio-blk uses a response footer and virtio-scsi uses a response header, fixing virtio-blk is much harder. You need to add a new argument to virtqueue_push. I'd really prefer someone else to do it... Paolo
On Mon, Apr 27, 2015 at 03:28:34PM +0200, Paolo Bonzini wrote: > > > On 27/04/2015 15:23, Michael S. Tsirkin wrote: > > On Mon, Apr 27, 2015 at 02:29:25PM +0200, Paolo Bonzini wrote: > >> > qsgl->size is the size of the data field after the request or > >> > response header (virtio-scsi currently supports only one such > >> > field; bidirectional requests are not supported). However, > >> > the used ring's len field is not concerned about the field > >> > after the request header, so do not count it unless req->mode > >> > signals the request was a read. > >> > > >> > Also, do not report that anything was written if the request > >> > failed, and subtract any residual bytes in case of buffer underrun. > >> > > >> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > > Acked-by: Michael S. Tsirkin <mst@redhat.com> > > > > Pls merge through the storage tree. > > Ok, I'll take it through the SCSI tree then. > > > Also, can you pls fix up blk similarly? > > Because virtio-blk uses a response footer and virtio-scsi uses a > response header, fixing virtio-blk is much harder. You need to add a > new argument to virtqueue_push. I'd really prefer someone else to do it... > > Paolo OK but what's the desired API? Do you know the host length or might any part of iov be dirty?
On 27/04/2015 16:04, Michael S. Tsirkin wrote: >> > Because virtio-blk uses a response footer and virtio-scsi uses a >> > response header, fixing virtio-blk is much harder. You need to add a >> > new argument to virtqueue_push. I'd really prefer someone else to do it... >> > >> > Paolo > OK but what's the desired API? > Do you know the host length or might any part of iov > be dirty? For a 1-sector request and a 2048+1 bytes iov, I know that I've written bytes 0-511 and byte 2048. So I have to dirty all 2049 bytes, but the written length should be 512. Right now we pass 2049 to virtqueue_push and write 2049 to the written length, I'd need another argument to pass the 512. Paolo
On Mon, Apr 27, 2015 at 04:18:43PM +0200, Paolo Bonzini wrote: > > > On 27/04/2015 16:04, Michael S. Tsirkin wrote: > >> > Because virtio-blk uses a response footer and virtio-scsi uses a > >> > response header, fixing virtio-blk is much harder. You need to add a > >> > new argument to virtqueue_push. I'd really prefer someone else to do it... > >> > > >> > Paolo > > OK but what's the desired API? > > Do you know the host length or might any part of iov > > be dirty? > > For a 1-sector request and a 2048+1 bytes iov, I know that I've written > bytes 0-511 and byte 2048. > > So I have to dirty all 2049 bytes, but the written length should be 512. > Right now we pass 2049 to virtqueue_push and write 2049 to the written > length, I'd need another argument to pass the 512. > > Paolo OK, I sent a patch with a new API, pls take a look. Can you implement your patch on top?
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index c9bea06..4995f6e 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -65,6 +65,19 @@ void virtio_scsi_free_req(VirtIOSCSIReq *req) g_slice_free1(sizeof(*req) + vs->cdb_size, req); } +static size_t virtio_scsi_written_length(VirtIODevice *vdev, VirtIOSCSIReq *req) +{ + size_t sz = req->resp_iov.size; + + if (req->sreq && + req->mode == SCSI_XFER_FROM_DEV && + req->resp.cmd.response == VIRTIO_SCSI_S_OK) { + sz += req->qsgl.size - virtio_tswap32(vdev, req->resp.cmd.resid); + } + + return sz; +} + static void virtio_scsi_complete_req(VirtIOSCSIReq *req) { VirtIOSCSI *s = req->dev; @@ -76,7 +89,7 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req) assert(req->vq == NULL); virtio_scsi_vring_push_notify(req); } else { - virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size); + virtqueue_push(vq, &req->elem, virtio_scsi_written_length(vdev, req)); virtio_notify(vdev, vq); }
qsgl->size is the size of the data field after the request or response header (virtio-scsi currently supports only one such field; bidirectional requests are not supported). However, the used ring's len field is not concerned about the field after the request header, so do not count it unless req->mode signals the request was a read. Also, do not report that anything was written if the request failed, and subtract any residual bytes in case of buffer underrun. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- hw/scsi/virtio-scsi.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)