Re: [Qemu-devel] [Xen-devel] [Patch V1 3/3] xen: add pvUSB backend

[Juergen Gross]

Sorry, I just found time now to continue with this series.

On 27/10/15 19:54, Konrad Rzeszutek Wilk wrote:
> On Thu, Sep 03, 2015 at 12:45:13PM +0200, Juergen Gross wrote:
>> Add a backend for para-virtualized USB devices for xen domains.
>>
>> The backend is using host-libusb to forward USB requests from a
>> domain via libusb to the real device(s) passed through.
>>
>> Signed-off-by: Juergen Gross <address@hidden>
>> ---
>>  hw/usb/Makefile.objs         |    4 +
>>  hw/usb/xen-usb.c             | 1120 
>> ++++++++++++++++++++++++++++++++++++++++++
>>  hw/xenpv/xen_machine_pv.c    |    3 +
>>  include/hw/xen/xen_backend.h |   13 +-
>>  4 files changed, 1137 insertions(+), 3 deletions(-)
>>  create mode 100644 hw/usb/xen-usb.c
>>
>> diff --git a/hw/usb/Makefile.objs b/hw/usb/Makefile.objs
>> index 3fe4dff..0253184 100644
>> --- a/hw/usb/Makefile.objs
>> +++ b/hw/usb/Makefile.objs
>> @@ -36,3 +36,7 @@ common-obj-$(CONFIG_USB_REDIR) += redirect.o quirks.o
>>  
>>  # usb pass-through
>>  common-obj-y += $(patsubst %,host-%.o,$(HOST_USB))
>> +
>> +ifeq ($(CONFIG_USB_LIBUSB),y)
>> +common-obj-$(CONFIG_XEN_BACKEND) += xen-usb.o
>> +endif
>> diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c
>> new file mode 100644
>> index 0000000..2570bd7
>> --- /dev/null
>> +++ b/hw/usb/xen-usb.c
>> @@ -0,0 +1,1120 @@
>> +/*
>> + *  xen paravirt usb device backend
>> + *
>> + *  (c) Juergen Gross <address@hidden>
>> + *
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; under version 2 of the License.
>> + *
>> + *  This program is distributed in the hope that it will be useful,
>> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + *  GNU General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License along
>> + *  with this program; if not, see <http://www.gnu.org/licenses/>.
>> + *
>> + *  Contributions after 2012-01-13 are licensed under the terms of the
>> + *  GNU GPL, version 2 or (at your option) any later version.
>> + */
>> +
>> +#include <libusb.h>
>> +#include <sys/types.h>
>> +#include <sys/mman.h>
>> +#include <sys/time.h>
>> +
>> +#include "qemu-common.h"
>> +#include "qemu/config-file.h"
>> +#include "hw/sysbus.h"
>> +#include "hw/usb.h"
>> +#include "hw/xen/xen_backend.h"
>> +#include "monitor/qdev.h"
>> +#include "qapi/qmp/qbool.h"
>> +#include "qapi/qmp/qint.h"
>> +#include "qapi/qmp/qstring.h"
>> +#include "sys/user.h"
>> +
>> +#include <xen/io/ring.h>
>> +#include <xen/io/usbif.h>
>> +
>> +#define TR(fmt, args...)                                            \
>> +    {                                                               \
>> +        struct timeval tv;                                          \
>> +                                                                    \
>> +        gettimeofday(&tv, NULL);                                    \
>> +        fprintf(stderr, "%8ld.%06ld xen-usb(%s):" fmt, tv.tv_sec,   \
>> +                tv.tv_usec, __func__, ##args);                      \
>> +    }
>> +#define TR_REQ(fmt, args...) { if (tr_debug & 1) TR(fmt, ##args) }
>> +#define TR_BUS(fmt, args...) { if (tr_debug & 2) TR(fmt, ##args) }
>> +
>> +#define USBBACK_MAXPORTS        USBIF_PIPE_PORT_MASK
>> +#define USBBACK_DEVNAME_SIZE    32
> 
> That does not seem to be used
>> +#define USB_DEV_ADDR_SIZE       128
>> +
>> +struct usbif_ctrlrequest {
>> +    uint8_t    bRequestType;
>> +    uint8_t    bRequest;
>> +    uint16_t   wValue;
>> +    uint16_t   wIndex;
>> +    uint16_t   wLength;
>> +};
> 
> Would it make sense to mention that this is part of the ABI?

It is part of the USB hardware interface. I'll add a comment.

> And if so perhaps a pointer where this in the Xen code base?
> 
>> +
>> +struct usbif_isoc_descriptor {
>> +    uint32_t   offset;
>> +    uint32_t   length;
>> +    uint32_t   actual_length;
>> +    int32_t    status;
>> +};
> 
> Ditto?

ISOC code is remove from this patch, so I'll address this later.

> 
>> +
>> +struct usbback_info;
>> +struct usbback_req;
>> +
>> +struct usbback_stub {
>> +    USBDevice  *dev;
>> +    USBPort    port;
>> +    unsigned   speed;
> 
> unsigned int?

Okay.

>> +    bool       attached;
>> +    QTAILQ_HEAD(submit_q_head, usbback_req) submit_q;
>> +};
>> +
>> +struct usbback_req {
>> +    struct usbback_info      *usbif;
>> +    struct usbback_stub      *stub;
>> +    struct usbif_urb_request req;
>> +    USBPacket                packet;
>> +
>> +    unsigned int             nr_buffer_segs; /* # of transfer_buffer 
>> segments */
>> +    unsigned int             nr_extra_segs;  /* # of iso_frame_desc 
>> segments  */
>> +
>> +    QTAILQ_ENTRY(usbback_req) q;
>> +
>> +    void                     *buffer;
>> +    void                     *isoc_buffer;
>> +    struct libusb_transfer   *xfer;
>> +};
>> +
>> +struct usbback_info {
>> +    struct XenDevice         xendev;  /* must be first */
>> +    USBBus                   bus;
>> +    void                     *urb_sring;
>> +    void                     *conn_sring;
>> +    struct usbif_urb_back_ring urb_ring;
>> +    struct usbif_conn_back_ring conn_ring;
>> +    int                      num_ports;
>> +    int                      usb_ver;
>> +    bool                     ring_error;
>> +    QTAILQ_HEAD(req_free_q_head, usbback_req) req_free_q;
>> +    struct usbback_stub      ports[USBBACK_MAXPORTS];
>> +    struct usbback_stub      *addr_table[USB_DEV_ADDR_SIZE];
>> +    QEMUBH                   *bh;
>> +};
>> +
>> +static unsigned int tr_debug = 3;
> 
> This surely should be zero :-)

Removed with the switch to xen_be_printf()

> 
>> +
>> +static void usbback_copy_buffer(struct usbback_req *usbback_req,
>> +                                struct usbif_isoc_descriptor *iso, bool out,
>> +                                unsigned len, unsigned off)
>> +{
>> +    struct usbif_request_segment *seg;
>> +    unsigned s, offset, copy_len, copy_off;
>> +    void *addr;
>> +
>> +    offset = 0;
>> +    copy_off = iso->offset;
>> +    for (s = 0; len && s < usbback_req->nr_buffer_segs; s++) {
>> +        seg = usbback_req->req.seg + s;
>> +        if (offset + seg->length > copy_off) {
>> +            addr = usbback_req->buffer + s * PAGE_SIZE + seg->offset +
>> +                   copy_off - offset;
>> +            copy_len = len;
>> +            if (copy_len > seg->length - copy_off + offset) {
>> +                copy_len = seg->length - copy_off + offset;
>> +            }
>> +            if (out) {
>> +                memcpy(usbback_req->xfer->buffer + off, addr, copy_len);
>> +            } else {
>> +                memcpy(addr, usbback_req->xfer->buffer + off, copy_len);
>> +            }
>> +            len -= copy_len;
>> +            off += copy_len;
>> +        }
>> +        offset += usbback_req->req.seg[s].length;
>> +    }
>> +    assert(!len);
>> +}
>> +
>> +int usbback_get_packets(USBPacket *p)
> 
> static ?

ISOC: removed

> 
>> +{
>> +    struct usbback_req *usbback_req;
>> +
>> +    usbback_req = container_of(p, struct usbback_req, packet);
>> +    assert(usbif_pipeisoc(usbback_req->req.pipe));
>> +    return usbback_req->req.u.isoc.nr_frame_desc_segs;
>> +}
>> +
>> +void usbback_set_iso_desc(USBPacket *p, struct libusb_transfer *xfer)
>> +{
>> +    struct usbback_req *usbback_req;
>> +    struct usbif_isoc_descriptor *iso;
>> +    struct usbif_request_segment *seg;
>> +    unsigned i, j, np, descr, off;
>> +
>> +    usbback_req = container_of(p, struct usbback_req, packet);
>> +    assert(usbif_pipeisoc(usbback_req->req.pipe));
>> +    usbback_req->xfer = xfer;
>> +    np = usbback_req->req.u.isoc.nr_frame_desc_segs;
>> +    descr = 0;
>> +    off = 0;
>> +
>> +    for (i = 0; i < usbback_req->nr_extra_segs; i++) {
>> +        seg = usbback_req->req.seg + usbback_req->nr_buffer_segs + i;
>> +        iso = usbback_req->isoc_buffer + i * PAGE_SIZE + seg->offset;
>> +        if ((seg->length % sizeof(*iso)) ||
>> +            (seg->length / sizeof(*iso) > np - descr) ||
>> +            (iso->offset + iso->length > usbback_req->req.buffer_length)) {
>> +            xen_be_printf(&usbback_req->usbif->xendev, 0,
>> +                          "iso segment length invalid\n");
>> +            xfer->num_iso_packets = descr;
>> +            while (descr < usbback_req->req.u.isoc.nr_frame_desc_segs) {
>> +                xfer->iso_packet_desc[descr].length = 0;
>> +                xfer->iso_packet_desc[descr].actual_length = 0;
>> +                descr++;
>> +            }
>> +            return;
>> +        }
>> +        for (j = 0; j < seg->length / sizeof(*iso); j++) {
>> +            xfer->iso_packet_desc[descr].length = iso->length;
>> +            xfer->iso_packet_desc[descr].actual_length = 0;
>> +            if (!usbif_pipein(usbback_req->req.pipe)) {
>> +                usbback_copy_buffer(usbback_req, iso, true, iso->length, 
>> off);
>> +                off += iso->length;
>> +            }
>> +            iso++;
>> +            descr++;
>> +        }
>> +    }
>> +}
>> +
>> +static struct usbback_req *usbback_get_req(struct usbback_info *usbif)
>> +{
>> +    struct usbback_req *usbback_req;
>> +
>> +    if (QTAILQ_EMPTY(&usbif->req_free_q)) {
>> +        usbback_req = g_malloc0(sizeof(*usbback_req));
>> +    } else {
>> +        usbback_req = QTAILQ_FIRST(&usbif->req_free_q);
>> +        QTAILQ_REMOVE(&usbif->req_free_q, usbback_req, q);
>> +    }
>> +    return usbback_req;
>> +}
>> +
>> +static void usbback_put_req(struct usbback_req *usbback_req)
>> +{
>> +    struct usbback_info *usbif;
>> +
>> +    usbif = usbback_req->usbif;
>> +    memset(usbback_req, 0, sizeof(*usbback_req));
>> +    QTAILQ_INSERT_HEAD(&usbif->req_free_q, usbback_req, q);
>> +}
>> +
>> +static int usbback_gnttab_map(struct usbback_info *usbif,
>> +                              struct usbback_req *usbback_req)
>> +{
>> +    unsigned int nr_segs, i, prot;
>> +    uint32_t ref[USBIF_MAX_SEGMENTS_PER_REQUEST];
>> +    struct XenDevice *xendev = &usbif->xendev;
>> +    struct usbif_request_segment *seg;
>> +    void *addr;
>> +
>> +    nr_segs = usbback_req->nr_buffer_segs + usbback_req->nr_extra_segs;
>> +    if (!nr_segs) {
>> +        return 0;
>> +    }
>> +
>> +    if (nr_segs > USBIF_MAX_SEGMENTS_PER_REQUEST) {
>> +        xen_be_printf(xendev, 0, "bad number of segments in request (%d)\n",
>> +                      nr_segs);
>> +        return -EINVAL;
>> +    }
>> +
>> +    for (i = 0; i < nr_segs; i++) {
>> +        if ((unsigned)usbback_req->req.seg[i].offset +
>> +            (unsigned)usbback_req->req.seg[i].length > PAGE_SIZE) {
>> +            xen_be_printf(xendev, 0, "segment crosses page boundary\n");
>> +            return -EINVAL;
>> +        }
>> +    }
>> +
>> +    if (usbback_req->nr_buffer_segs) {
>> +        prot = PROT_READ;
>> +        if (usbif_pipein(usbback_req->req.pipe)) {
>> +                prot |= PROT_WRITE;
>> +        }
>> +        for (i = 0; i < usbback_req->nr_buffer_segs; i++) {
>> +            ref[i] = usbback_req->req.seg[i].gref;
>> +        }
>> +        usbback_req->buffer = 
>> xc_gnttab_map_domain_grant_refs(xendev->gnttabdev,
>> +            usbback_req->nr_buffer_segs, xendev->dom, ref, prot);
>> +
>> +        if (!usbback_req->buffer) {
>> +            return -ENOMEM;
>> +        }
>> +
>> +        for (i = 0; i < usbback_req->nr_buffer_segs; i++) {
>> +            seg = usbback_req->req.seg + i;
>> +            addr = usbback_req->buffer + i * PAGE_SIZE + seg->offset;
>> +            qemu_iovec_add(&usbback_req->packet.iov, addr, seg->length);
>> +        }
>> +    }
>> +
>> +    if (!usbif_pipeisoc(usbback_req->req.pipe)) {
>> +        return 0;
>> +    }
>> +
>> +    if (!usbback_req->nr_extra_segs) {
>> +        xen_be_printf(xendev, 0, "iso request without descriptor 
>> segments\n");
>> +        return -EINVAL;
> 
> Could this be moved before the xc_gnttab_map_domain_grant_refs and 
> qemu_iovec_add
> is done? And should you unmap ->buffer?

No, this is isoc only (I'm keeping the main infrastructure for
isoc requests). And ->buffer is unmapped in usbback_do_response()
which is called in error case.

> 
>> +    }
>> +
>> +    prot = PROT_READ | PROT_WRITE;
>> +    for (i = 0; i < usbback_req->nr_extra_segs; i++) {
>> +        ref[i] = usbback_req->req.seg[i + 
>> usbback_req->req.nr_buffer_segs].gref;
>> +    }
>> +    usbback_req->isoc_buffer = xc_gnttab_map_domain_grant_refs(
>> +         xendev->gnttabdev, usbback_req->nr_extra_segs, xendev->dom, ref, 
>> prot);
>> +
>> +    if (!usbback_req->isoc_buffer) {
> 
> No unmapping of the ->buffer?

As above.

> 
>> +        return -ENOMEM;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int usbback_init_packet(struct usbback_req *usbback_req)
>> +{
>> +    USBPacket *packet = &usbback_req->packet;
>> +    USBDevice *dev = usbback_req->stub->dev;
>> +    USBEndpoint *ep;
>> +    unsigned int pid, ep_nr;
>> +    bool sok;
>> +
>> +    qemu_iovec_init(&packet->iov, USBIF_MAX_SEGMENTS_PER_REQUEST);
>> +    pid = usbif_pipein(usbback_req->req.pipe) ? USB_TOKEN_IN : 
>> USB_TOKEN_OUT;
>> +    ep_nr = usbif_pipeendpoint(usbback_req->req.pipe);
>> +    sok = !!(usbback_req->req.transfer_flags & 1);
>> +    if (usbif_pipetype(usbback_req->req.pipe) == USBIF_PIPE_TYPE_CTRL) {
>> +        ep_nr = 0;
>> +        sok = false;
>> +    }
>> +    ep = usb_ep_get(dev, pid, ep_nr);
>> +    usb_packet_setup(packet, pid, ep, 0, 1, sok, true);
>> +
>> +    switch (usbif_pipetype(usbback_req->req.pipe)) {
>> +    case USBIF_PIPE_TYPE_ISOC:
>> +        TR_REQ("iso transfer %s: buflen: %x, %d frames\n",
>> +               (pid == USB_TOKEN_IN) ? "in" : "out",
>> +               usbback_req->req.buffer_length,
>> +               usbback_req->req.u.isoc.nr_frame_desc_segs);
>> +        break;
>> +
>> +    case USBIF_PIPE_TYPE_INT:
>> +        TR_REQ("int transfer %s: buflen: %x\n",
>> +               (pid == USB_TOKEN_IN) ? "in" : "out",
>> +               usbback_req->req.buffer_length);
>> +        break;
>> +
>> +    case USBIF_PIPE_TYPE_CTRL:
>> +        packet->parameter = *(uint64_t *)usbback_req->req.u.ctrl;
>> +        TR_REQ("ctrl parameter: %lx, buflen: %x\n", packet->parameter,
>> +               usbback_req->req.buffer_length);
>> +        break;
>> +
>> +    case USBIF_PIPE_TYPE_BULK:
>> +        TR_REQ("bulk transfer %s: buflen: %x\n",
>> +               (pid == USB_TOKEN_IN) ? "in" : "out",
>> +               usbback_req->req.buffer_length);
>> +        break;
>> +    default:
>> +        return -EINVAL;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static void usbback_do_response(struct usbback_req *usbback_req,
>> +                                int32_t status, int32_t actual_length,
>> +                                int32_t error_count)
> 
> Should the 'actual_length' and 'error_count' be unsigned int?

Same type as in the interface header. Changing this would probably
make sense, but this is out of scope for this series.

>> +{
>> +    struct usbback_info *usbif;
>> +    struct usbif_urb_response *res;
>> +    struct XenDevice *xendev;
>> +    unsigned int notify;
>> +
>> +    TR_REQ("id %d, status %d, length %d, errcnt %d\n", usbback_req->req.id,
>> +           status, actual_length, error_count);
>> +
>> +    usbif = usbback_req->usbif;
>> +    xendev = &usbif->xendev;
>> +
>> +    if (usbback_req->packet.iov.iov) {
> 
> qemu_iovec_is_zero ?

No. Would be true if qemu_iovec_add() wasn't called, but we need to call
qemu_iovec_destroy() in this case, too.

> 
>> +        qemu_iovec_destroy(&usbback_req->packet.iov);
>> +    }
>> +
>> +    if (usbback_req->buffer) {
>> +        xc_gnttab_munmap(xendev->gnttabdev, usbback_req->buffer,
>> +                         usbback_req->nr_buffer_segs);
>> +        usbback_req->buffer = NULL;
> 
> nr_buffer_segs = 0?

Not needed. Will be set _always_ in case of buffer != NULL.

> 
>> +    }
>> +
>> +    if (usbback_req->isoc_buffer) {
>> +        xc_gnttab_munmap(xendev->gnttabdev, usbback_req->isoc_buffer,
>> +                         usbback_req->nr_extra_segs);
> 
> nr_extra_segts = 0 ?
> Should 'isoc_buffer' be set to NULL as well?

Setting isoc_buffer to NULL seems to be a good idea.

> 
>> +    }
>> +
>> +    res = RING_GET_RESPONSE(&usbif->urb_ring, usbif->urb_ring.rsp_prod_pvt);
>> +    res->id = usbback_req->req.id;
>> +    res->status = status;
>> +    res->actual_length = actual_length;
>> +    res->error_count = error_count;
>> +    res->start_frame = 0;
>> +    usbif->urb_ring.rsp_prod_pvt++;
>> +    RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&usbif->urb_ring, notify);
>> +
>> +    if (notify) {
>> +        xen_be_send_notify(xendev);
>> +    }
>> +
>> +    usbback_put_req(usbback_req);
>> +}
>> +
>> +static void usbback_do_response_ret(struct usbback_req *usbback_req,
>> +                                    int32_t status)
>> +{
>> +    usbback_do_response(usbback_req, status, 0, 0);
>> +}
>> +
>> +static int32_t usbback_xlat_status(int32_t status)
>> +{
>> +    int32_t ret = -ESHUTDOWN;
>> +
>> +    switch (status) {
>> +    case USB_RET_SUCCESS:
>> +        ret = 0;
>> +        break;
>> +    case USB_RET_NODEV:
>> +        ret = -ENODEV;
>> +        break;
>> +    case USB_RET_STALL:
>> +        ret = -EPIPE;
>> +        break;
>> +    case USB_RET_BABBLE:
>> +        ret = -EOVERFLOW;
>> +        break;
>> +    case USB_RET_IOERROR:
>> +        ret = -EPROTO;
>> +        break;
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +static void usbback_packet_complete(USBPacket *packet)
>> +{
>> +    struct usbback_req *usbback_req;
>> +    int32_t status, error_count, actual_length;
>> +    unsigned int i, j, off;
>> +    struct usbif_isoc_descriptor *iso;
>> +    struct usbif_request_segment *seg;
>> +    struct libusb_iso_packet_descriptor *libusb_iso;
>> +
>> +    error_count = 0;
>> +    actual_length = 0;
>> +    off = 0;
>> +    usbback_req = container_of(packet, struct usbback_req, packet);
>> +
>> +    QTAILQ_REMOVE(&usbback_req->stub->submit_q, usbback_req, q);
>> +
>> +    status = usbback_xlat_status(packet->status);
>> +    if (usbback_req->isoc_buffer) {
>> +        libusb_iso = usbback_req->xfer->iso_packet_desc;
>> +        j = 0;
>> +        for (i = 0; i < usbback_req->nr_extra_segs; i++) {
>> +            seg = usbback_req->req.seg + usbback_req->nr_buffer_segs + i;
>> +            iso = usbback_req->isoc_buffer + i * PAGE_SIZE + seg->offset;
>> +            for (j = 0; j < seg->length / sizeof(*iso); j++) {
>> +                iso->actual_length = libusb_iso->actual_length;
>> +                iso->status = usbback_xlat_status(libusb_iso->status);
>> +                actual_length += libusb_iso->actual_length;
>> +                error_count += iso->status ? 1 : 0;
>> +                if (usbif_pipein(usbback_req->req.pipe)) {
>> +                    usbback_copy_buffer(usbback_req, iso, false,
>> +                                        iso->actual_length, off);
>> +                    off += iso->length;
>> +                }
>> +                libusb_iso++;
>> +                iso++;
>> +            }
>> +        }
>> +    } else {
>> +        actual_length = packet->actual_length;
>> +    }
>> +
>> +    usbback_do_response(usbback_req, status, actual_length, error_count);
>> +}
>> +
>> +static void usbback_set_address(struct usbback_info *usbif,
>> +                                struct usbback_stub *stub, int cur_addr,
>> +                                int new_addr)
>> +{
>> +    if (cur_addr) {
>> +        usbif->addr_table[cur_addr] = NULL;
>> +    }
>> +    if (new_addr) {
>> +        usbif->addr_table[new_addr] = stub;
>> +    }
>> +}
>> +
>> +static bool usbback_cancel_req(struct usbback_req *usbback_req)
>> +{
>> +    bool ret = false;
>> +
>> +    if (usb_packet_is_inflight(&usbback_req->packet)) {
>> +        usb_cancel_packet(&usbback_req->packet);
>> +        ret = true;
>> +    }
>> +    return ret;
>> +}
>> +
>> +static void usbback_process_unlink_req(struct usbback_req *usbback_req)
>> +{
>> +    struct usbback_info *usbif;
>> +    struct usbback_req *unlink_req;
>> +    unsigned int id, devnum;
>> +    int ret;
> 
> Why 'ret'? You are not returning the value.

It's the return status of the request (parameter of
usbback_do_response_ret()).

> 
>> +
>> +    usbif = usbback_req->usbif;
>> +    ret = 0;
>> +    id = usbback_req->req.u.unlink.unlink_id;
>> +    TR_REQ("unlink id %d\n", id);
>> +    devnum = usbif_pipedevice(usbback_req->req.pipe);
>> +    if (unlikely(devnum == 0)) {
>> +        usbback_req->stub = usbif->ports +
>> +                            usbif_pipeportnum(usbback_req->req.pipe);
> 
> Should you check that usbif_pipeporntnum value does not exceeed 
> USBBACK_MAXPORTS ?
> Ah, no. The macro usbif_piportnum will mask it so it will always be within
> ports[0..USBBACK_MAXPORTS].
> 
>> +        if (unlikely(!usbback_req->stub)) {
>> +            ret = -ENODEV;
>> +            goto fail_response;
>> +        }
>> +    } else {
>> +        if (unlikely(!usbif->addr_table[devnum])) {
> 
> Should we doublecheck that devnm < USB_DEV_ADDR_SIZE ?

I think it's better to do:

#define USB_DEV_ADDR_SIZE       (USBIF_PIPE_DEV_MASK + 1)

> 
>> +            ret = -ENODEV;
>> +            goto fail_response;
>> +        }
>> +        usbback_req->stub = usbif->addr_table[devnum];
>> +    }
>> +
>> +    QTAILQ_FOREACH(unlink_req, &usbback_req->stub->submit_q, q) {
>> +        if (unlink_req->req.id == id) {
>> +            if (usbback_cancel_req(unlink_req)) {
>> +                usbback_do_response_ret(unlink_req, -EPROTO);
>> +            }
>> +            break;
>> +        }
>> +    }
>> +
>> +fail_response:
>> +    usbback_do_response_ret(usbback_req, ret);
>> +}
>> +
> 
> Could you add a comment explaining what positive return values mean?

Okay.

> 
>> +static int usbback_check_and_submit(struct usbback_req *usbback_req)
>> +{
>> +    struct usbback_info *usbif;
>> +    unsigned int devnum;
>> +    struct usbback_stub *stub;
>> +    struct usbif_ctrlrequest *ctrl;
>> +    int ret;
>> +    uint16_t wValue;
>> +
>> +    usbif = usbback_req->usbif;
>> +    stub = NULL;
>> +    devnum = usbif_pipedevice(usbback_req->req.pipe);
>> +    ctrl = (struct usbif_ctrlrequest *)usbback_req->req.u.ctrl;
>> +    wValue = le16_to_cpu(ctrl->wValue);
>> +
>> +    /*
>> +     * When the device is first connected or resetted, USB device has no
>> +     * address. In this initial state, following requests are sent to device
>> +     * address (#0),
>> +     *
>> +     *  1. GET_DESCRIPTOR (with Descriptor Type is "DEVICE") is sent,
>> +     *     and OS knows what device is connected to.
>> +     *
>> +     *  2. SET_ADDRESS is sent, and then device has its address.
>> +     *
>> +     * In the next step, SET_CONFIGURATION is sent to addressed device, and
>> +     * then the device is finally ready to use.
>> +     */
>> +    if (unlikely(devnum == 0)) {
>> +        stub = usbif->ports + usbif_pipeportnum(usbback_req->req.pipe) - 1;
>> +        if (!stub->dev || !stub->attached) {
>> +            ret = -ENODEV;
>> +            goto do_response;
>> +        }
>> +
>> +        switch (ctrl->bRequest) {
>> +        case USB_REQ_GET_DESCRIPTOR:
>> +            /*
>> +             * GET_DESCRIPTOR request to device #0.
>> +             * through to normal transfer.
> 
> s/to//
>> +             */
>> +            TR_REQ("devnum 0 GET_DESCRIPTOR\n");
>> +            usbback_req->stub = stub;
>> +            return 0;
>> +        case USB_REQ_SET_ADDRESS:
>> +            /*
>> +             * SET_ADDRESS request to device #0.
>> +             * add attached device to addr_table.
>> +             */
>> +            TR_REQ("devnum 0 SET_ADDRESS\n");
>> +            usbback_set_address(usbif, stub, 0, wValue);
>> +            ret = 0;
>> +            break;
>> +        default:
>> +            ret = -EINVAL;
>> +            break;
>> +        }
>> +        goto do_response;
>> +    }
>> +
>> +    if (unlikely(!usbif->addr_table[devnum])) {
>> +            ret = -ENODEV;
>> +            goto do_response;
>> +    }
>> +    usbback_req->stub = usbif->addr_table[devnum];
>> +
>> +    /*
>> +     * Check special request
>> +     */
>> +    if (ctrl->bRequest != USB_REQ_SET_ADDRESS) {
>> +        return 0;
>> +    }
>> +
>> +    /*
>> +     * SET_ADDRESS request to addressed device.
>> +     * change addr or remove from addr_table.
>> +     */
>> +    usbback_set_address(usbif, usbback_req->stub, devnum, wValue);
>> +    ret = 0;
>> +
>> +do_response:
>> +    usbback_do_response_ret(usbback_req, ret);
>> +    return 1;
>> +}
>> +
>> +static void usbback_dispatch(struct usbback_req *usbback_req)
>> +{
>> +    int ret;
>> +    unsigned int devnum;
>> +    struct usbback_info *usbif;
>> +
>> +    TR_REQ("start req_id %d pipe %08x\n", usbback_req->req.id,
>> +           usbback_req->req.pipe);
>> +
>> +    usbif = usbback_req->usbif;
>> +
>> +    /* unlink request */
>> +    if (unlikely(usbif_pipeunlink(usbback_req->req.pipe))) {
>> +        usbback_process_unlink_req(usbback_req);
>> +        return;
>> +    }
>> +
>> +    if (usbif_pipectrl(usbback_req->req.pipe)) {
>> +        if (usbback_check_and_submit(usbback_req)) {
> 
> Should you at least report the errors if there are any?

Hmm, why? These are parameter errors which are the fault of the frontend
only. The frontend shouldn't be capable of flooding the backend's log.

> 
>> +            return;
>> +        }
>> +    } else {
>> +        devnum = usbif_pipedevice(usbback_req->req.pipe);
>> +        usbback_req->stub = usbif->addr_table[devnum];
>> +
>> +        if (!usbback_req->stub || !usbback_req->stub->attached) {
>> +            ret = -ENODEV;
>> +            goto fail_response;
>> +        }
>> +    }
>> +
>> +    QTAILQ_INSERT_TAIL(&usbback_req->stub->submit_q, usbback_req, q);
>> +
>> +    usbback_req->nr_buffer_segs = usbback_req->req.nr_buffer_segs;
>> +    usbback_req->nr_extra_segs = usbif_pipeisoc(usbback_req->req.pipe) ?
>> +                                 usbback_req->req.u.isoc.nr_frame_desc_segs 
>> : 0;
>> +
>> +    ret = usbback_init_packet(usbback_req);
>> +    if (ret) {
>> +        xen_be_printf(&usbif->xendev, 0, "invalid request\n");
>> +        ret = -ESHUTDOWN;
>> +        goto fail_free_urb;
>> +    }
>> +
>> +    ret = usbback_gnttab_map(usbif, usbback_req);
>> +    if (ret) {
>> +        xen_be_printf(&usbif->xendev, 0, "invalid buffer\n");
> 
> Should the 'ret' be at least included?

Hmm, yes.

> 
>> +        ret = -ESHUTDOWN;
>> +        goto fail_free_urb;
>> +    }
>> +
>> +    usb_handle_packet(usbback_req->stub->dev, &usbback_req->packet);
>> +    if (usbback_req->packet.status != USB_RET_ASYNC) {
>> +        usbback_packet_complete(&usbback_req->packet);
>> +    }
>> +    return;
>> +
>> +fail_free_urb:
>> +    QTAILQ_REMOVE(&usbback_req->stub->submit_q, usbback_req, q);
>> +
>> +fail_response:
>> +    usbback_do_response_ret(usbback_req, ret);
>> +}
>> +
>> +static void usbback_bh(void *opaque)
>> +{
>> +    struct usbback_info *usbif;
>> +    struct usbif_urb_back_ring *urb_ring;
>> +    struct usbback_req *usbback_req;
>> +    RING_IDX rc, rp;
>> +    unsigned int more_to_do;
>> +
>> +    usbif = opaque;
>> +    if (usbif->ring_error) {
>> +        return;
>> +    }
>> +
>> +    urb_ring = &usbif->urb_ring;
>> +    rc = urb_ring->req_cons;
>> +    rp = urb_ring->sring->req_prod;
>> +    xen_rmb(); /* Ensure we see queued requests up to 'rp'. */
>> +
>> +    if (RING_REQUEST_PROD_OVERFLOW(urb_ring, rp)) {
>> +        rc = urb_ring->rsp_prod_pvt;
>> +        xen_be_printf(&usbif->xendev, 0, "domU provided bogus ring requests 
>> "
>> +                      "(%#x - %#x = %u). Halting ring processing.\n",
>> +                      rp, rc, rp - rc);
>> +        usbif->ring_error = true;
>> +        return;
>> +    }
>> +
>> +    while (rc != rp) {
>> +        if (RING_REQUEST_CONS_OVERFLOW(urb_ring, rc)) {
>> +            break;
>> +        }
>> +        usbback_req = usbback_get_req(usbif);
>> +
>> +        usbback_req->req = *RING_GET_REQUEST(urb_ring, rc);
>> +        usbback_req->usbif = usbif;
>> +
>> +        usbback_dispatch(usbback_req);
>> +
>> +        urb_ring->req_cons = ++rc;
>> +    }
>> +
>> +    RING_FINAL_CHECK_FOR_REQUESTS(urb_ring, more_to_do);
>> +    if (more_to_do) {
>> +        qemu_bh_schedule(usbif->bh);
>> +    }
>> +}
>> +
>> +static void usbback_hotplug_notify(struct usbback_info *usbif, unsigned 
>> port)
>> +{
>> +    struct usbif_conn_back_ring *ring = &usbif->conn_ring;
>> +    struct usbif_conn_request *req;
>> +    struct usbif_conn_response *res;
>> +    uint16_t id;
>> +    unsigned int notify;
>> +
>> +    if (!usbif->conn_sring) {
>> +        return;
>> +    }
>> +
>> +    req = RING_GET_REQUEST(ring, ring->req_cons);
>> +    id = req->id;
>> +    ring->req_cons++;
>> +    ring->sring->req_event = ring->req_cons + 1;
>> +
>> +    res = RING_GET_RESPONSE(ring, ring->rsp_prod_pvt);
>> +    res->id = id;
>> +    res->portnum = port;
>> +    res->speed = usbif->ports[port - 1].speed;
>> +    ring->rsp_prod_pvt++;
>> +    RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(ring, notify);
>> +
>> +    if (notify) {
>> +        xen_be_send_notify(&usbif->xendev);
>> +    }
>> +
>> +    TR_BUS("hotplug port %d speed %d\n", port, res->speed);
>> +}
>> +
>> +static void usbback_portid_remove(struct usbback_info *usbif, unsigned port)
>> +{
>> +    USBPort *p;
>> +
>> +    if (!usbif->ports[port - 1].dev) {
>> +        return;
>> +    }
>> +
>> +    p = &(usbif->ports[port - 1].port);
>> +    snprintf(p->path, sizeof(p->path), "%d", 99);
>> +
>> +    object_unparent(OBJECT(usbif->ports[port - 1].dev));
>> +    usbif->ports[port - 1].dev = NULL;
>> +    usbif->ports[port - 1].speed = USBIF_SPEED_NONE;
>> +    usbif->ports[port - 1].attached = false;
>> +    usbback_hotplug_notify(usbif, port);
>> +
>> +    TR_BUS("port %d removed\n", port);
>> +}
>> +
>> +static void usbback_portid_add(struct usbback_info *usbif, unsigned port,
>> +                               char *busid)
>> +{
>> +    unsigned speed;
>> +    char *portname;
>> +    USBPort *p;
>> +    Error *local_err = NULL;
>> +    QDict *qdict;
>> +    QemuOpts *opts;
>> +
>> +    if (usbif->ports[port - 1].dev) {
>> +        return;
>> +    }
>> +
>> +    portname = strchr(busid, '-');
>> +    if (!portname) {
>> +        xen_be_printf(&usbif->xendev, 0, "device %s illegal 
>> specification\n",
>> +                      busid);
>> +        return;
>> +    }
>> +    portname++;
>> +    p = &(usbif->ports[port - 1].port);
>> +    snprintf(p->path, sizeof(p->path), "%s", portname);
>> +
>> +    qdict = qdict_new();
>> +    qdict_put(qdict, "driver", qstring_from_str("usb-host"));
>> +    qdict_put(qdict, "hostbus", qint_from_int(atoi(busid)));
>> +    qdict_put(qdict, "hostport", qstring_from_str(portname));
>> +    qdict_put(qdict, "xen-iso-passthrough", qbool_from_int(1));
>> +    opts = qemu_opts_from_qdict(qemu_find_opts("device"), qdict, 
>> &local_err);
>> +    if (local_err) {
>> +        goto err;
>> +    }
>> +    usbif->ports[port - 1].dev = USB_DEVICE(qdev_device_add(opts));
>> +    if (!usbif->ports[port - 1].dev) {
>> +        goto err;
>> +    }
>> +    QDECREF(qdict);
>> +    snprintf(p->path, sizeof(p->path), "%d", port);
>> +    speed = usbif->ports[port - 1].dev->speed;
> 
> I am a bit confused as how you get the 'speed'? We are adding a device
> and we don't read this?

Huh? I don't understand. We exactly do this: we are adding a device
and then we read the speed to be able to report it.

> 
> 
>> +    switch (speed) {
>> +    case USB_SPEED_LOW:
>> +        speed = USBIF_SPEED_LOW;
>> +        break;
>> +    case USB_SPEED_FULL:
>> +        speed = USBIF_SPEED_FULL;
>> +        break;
>> +    case USB_SPEED_HIGH:
>> +        speed = (usbif->usb_ver < USB_VER_USB20) ?
>> +                USBIF_SPEED_NONE : USBIF_SPEED_HIGH;
>> +        break;
>> +    default:
>> +        speed = USBIF_SPEED_NONE;
>> +        break;
>> +    }
>> +    if (speed == USBIF_SPEED_NONE) {
>> +        xen_be_printf(&usbif->xendev, 0, "device %s wrong speed\n", busid);
>> +        object_unparent(OBJECT(usbif->ports[port - 1].dev));
>> +        usbif->ports[port - 1].dev = NULL;
>> +        return;
>> +    }
>> +    usb_device_reset(usbif->ports[port - 1].dev);
>> +    usbif->ports[port - 1].speed = speed;
>> +    usbif->ports[port - 1].attached = true;
>> +    QTAILQ_INIT(&usbif->ports[port - 1].submit_q);
>> +    usbback_hotplug_notify(usbif, port);
>> +
>> +    TR_BUS("port %d attached\n", port);
>> +    return;
>> +
>> +err:
>> +    QDECREF(qdict);
>> +    snprintf(p->path, sizeof(p->path), "%d", 99);
>> +    xen_be_printf(&usbif->xendev, 0, "device %s could not be opened\n", 
>> busid);
>> +}
>> +
>> +static void usbback_process_port(struct usbback_info *usbif, unsigned port)
>> +{
>> +    char node[8];
>> +    char *busid;
>> +
>> +    snprintf(node, sizeof(node), "port/%d", port);
>> +    busid = xenstore_read_be_str(&usbif->xendev, node);
>> +    if (busid == NULL) {
>> +        xen_be_printf(&usbif->xendev, 0, "xenstore_read %s failed\n", node);
>> +        return;
>> +    }
>> +
>> +    /* Remove portid, if the port is not connected.  */
>> +    if (strlen(busid) == 0) {
>> +        usbback_portid_remove(usbif, port);
>> +    } else {
>> +        usbback_portid_add(usbif, port, busid);
>> +    }
>> +
>> +    g_free(busid);
>> +}
>> +
>> +static void usbback_disconnect(struct XenDevice *xendev)
>> +{
>> +    struct usbback_info *usbif;
>> +    struct usbback_req *req, *tmp;
>> +    unsigned int i;
>> +
>> +    TR_BUS("start\n");
>> +
>> +    usbif = container_of(xendev, struct usbback_info, xendev);
>> +
>> +    xen_be_unbind_evtchn(xendev);
>> +
>> +    if (usbif->urb_sring) {
>> +        xc_gnttab_munmap(xendev->gnttabdev, usbif->urb_sring, 1);
>> +        usbif->urb_sring = NULL;
>> +    }
>> +    if (usbif->conn_sring) {
>> +        xc_gnttab_munmap(xendev->gnttabdev, usbif->conn_sring, 1);
>> +        usbif->conn_sring = NULL;
>> +    }
>> +
>> +    for (i = 0; i < usbif->num_ports; i++) {
>> +        if (!usbif->ports[i].dev) {
>> +            continue;
>> +        }
>> +        QTAILQ_FOREACH_SAFE(req, &usbif->ports[i].submit_q, q, tmp) {
>> +            usbback_cancel_req(req);
>> +        }
>> +    }
>> +
>> +    TR_BUS("finished\n");
>> +}
>> +
>> +static int usbback_connect(struct XenDevice *xendev)
>> +{
>> +    struct usbback_info *usbif;
>> +    struct usbif_urb_sring *urb_sring;
>> +    struct usbif_conn_sring *conn_sring;
>> +    int urb_ring_ref;
>> +    int conn_ring_ref;
>> +    unsigned int i;
>> +
>> +    TR_BUS("start\n");
>> +
>> +    usbif = container_of(xendev, struct usbback_info, xendev);
>> +
>> +    if (xenstore_read_fe_int(xendev, "urb-ring-ref", &urb_ring_ref)) {
>> +        TR("error reading urb-ring-ref\n");
>> +        return -1;
>> +    }
>> +    if (xenstore_read_fe_int(xendev, "conn-ring-ref", &conn_ring_ref)) {
>> +        TR("error reading conn-ring-ref\n");
>> +        return -1;
>> +    }
>> +    if (xenstore_read_fe_int(xendev, "event-channel", 
>> &xendev->remote_port)) {
>> +        TR("error reading event-channel\n");
>> +        return -1;
>> +    }
>> +
>> +    usbif->urb_sring = xc_gnttab_map_grant_ref(xendev->gnttabdev, 
>> xendev->dom,
>> +                                               urb_ring_ref,
>> +                                               PROT_READ | PROT_WRITE);
>> +    usbif->conn_sring = xc_gnttab_map_grant_ref(xendev->gnttabdev, 
>> xendev->dom,
>> +                                                conn_ring_ref,
>> +                                                PROT_READ | PROT_WRITE);
>> +    if (!usbif->urb_sring || !usbif->conn_sring) {
>> +        TR("error mapping rings\n");
>> +        usbback_disconnect(xendev);
>> +        return -1;
>> +    }
>> +
>> +    urb_sring = usbif->urb_sring;
>> +    conn_sring = usbif->conn_sring;
>> +    BACK_RING_INIT(&usbif->urb_ring, urb_sring, XC_PAGE_SIZE);
>> +    BACK_RING_INIT(&usbif->conn_ring, conn_sring, XC_PAGE_SIZE);
>> +
>> +    xen_be_bind_evtchn(xendev);
>> +
>> +    xen_be_printf(xendev, 1, "urb-ring-ref %d, conn-ring-ref %d, "
>> +                  "remote port %d, local port %d\n", urb_ring_ref,
>> +                  conn_ring_ref, xendev->remote_port, xendev->local_port);
>> +
>> +    for (i = 1; i <= usbif->num_ports; i++) {
>> +        if (usbif->ports[i - 1].dev) {
>> +            usbback_hotplug_notify(usbif, i);
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static void usbback_backend_changed(struct XenDevice *xendev, const char 
>> *node)
>> +{
>> +    struct usbback_info *usbif;
>> +    unsigned int i;
>> +
>> +    TR_BUS("path %s\n", node);
>> +
>> +    usbif = container_of(xendev, struct usbback_info, xendev);
>> +    for (i = 1; i <= usbif->num_ports; i++) {
>> +        usbback_process_port(usbif, i);
>> +    }
>> +}
>> +
>> +static int usbback_init(struct XenDevice *xendev)
>> +{
>> +    struct usbback_info *usbif;
>> +
>> +    TR_BUS("start\n");
>> +
>> +    usbif = container_of(xendev, struct usbback_info, xendev);
>> +
>> +    if (xenstore_read_be_int(xendev, "num-ports", &usbif->num_ports) ||
>> +        usbif->num_ports < 1 || usbif->num_ports > USBBACK_MAXPORTS) {
> 
> I think the compiler may be free to re-order these 'or' statements.

No. The C standard is very clear about this: logical or's are evaluated
from left to right. Otherwise something like: if (!buff || buff->x)
wouldn't work.

> 
> Could this be split in two 'if' ? One to get the value (and if it failed
> then print), and then the other 'if to check for the validity of it?
> 
>> +        xen_be_printf(xendev, 0, "num-ports not readable or out of 
>> bounds\n");
>> +        return -1;
>> +    }
>> +    if (xenstore_read_be_int(xendev, "usb-ver", &usbif->usb_ver) ||
>> +        (usbif->usb_ver != USB_VER_USB11 && usbif->usb_ver != 
>> USB_VER_USB20)) {
> 
> Ditto.
>> +        xen_be_printf(xendev, 0, "usb-ver not readable or out of bounds\n");
>> +        return -1;
>> +    }
>> +
>> +    usbback_backend_changed(xendev, "port");
>> +
>> +    TR_BUS("finished\n");
>> +
>> +    return 0;
>> +}
>> +
>> +static void xen_bus_attach(USBPort *port)
>> +{
>> +    struct usbback_info *usbif;
>> +
>> +    TR_BUS("called\n");
>> +    usbif = port->opaque;
>> +    usbif->ports[port->index].attached = true;
>> +    usbback_hotplug_notify(usbif, port->index + 1);
>> +}
>> +
>> +static void xen_bus_detach(USBPort *port)
>> +{
>> +    struct usbback_info *usbif;
>> +
>> +    TR_BUS("called\n");
>> +    usbif = port->opaque;
>> +    usbif->ports[port->index].attached = false;
>> +    usbback_hotplug_notify(usbif, port->index + 1);
>> +}
>> +
>> +static void xen_bus_child_detach(USBPort *port, USBDevice *child)
>> +{
>> +    TR_BUS("called\n");
>> +}
>> +
>> +static void xen_bus_complete(USBPort *port, USBPacket *packet)
>> +{
>> +    TR_REQ("called\n");
>> +    usbback_packet_complete(packet);
>> +}
>> +
>> +static USBPortOps xen_usb_port_ops = {
>> +    .attach = xen_bus_attach,
>> +    .detach = xen_bus_detach,
>> +    .child_detach = xen_bus_child_detach,
>> +    .complete = xen_bus_complete,
>> +};
>> +
>> +static USBBusOps xen_usb_bus_ops = {
>> +};
>> +
>> +static void usbback_alloc(struct XenDevice *xendev)
>> +{
>> +    struct usbback_info *usbif;
>> +    USBPort *p;
>> +    unsigned int i, max_grants;
>> +
>> +    usbif = container_of(xendev, struct usbback_info, xendev);
>> +
>> +    usb_bus_new(&usbif->bus, sizeof(usbif->bus), &xen_usb_bus_ops, 
>> xen_sysdev);
>> +    for (i = 0; i < USBBACK_MAXPORTS; i++) {
>> +        p = &(usbif->ports[i].port);
>> +        usb_register_port(&usbif->bus, p, usbif, i, &xen_usb_port_ops,
>> +                          USB_SPEED_MASK_LOW | USB_SPEED_MASK_FULL |
>> +                          USB_SPEED_MASK_HIGH);
>> +        snprintf(p->path, sizeof(p->path), "%d", 99);
>> +    }
>> +
>> +    QTAILQ_INIT(&usbif->req_free_q);
>> +    usbif->bh = qemu_bh_new(usbback_bh, usbif);
>> +
>> +    max_grants = USBIF_MAX_SEGMENTS_PER_REQUEST * USB_URB_RING_SIZE + 2;
> 
> Why the '2' ?

Connect and request rings. I'll add a comment.

> 
>> +    if (xc_gnttab_set_max_grants(xendev->gnttabdev, max_grants) < 0) {
>> +        xen_be_printf(xendev, 0, "xc_gnttab_set_max_grants failed: %s\n",
>> +                      strerror(errno));
>> +    }
>> +}
>> +
>> +static int usbback_free(struct XenDevice *xendev)
>> +{
>> +    struct usbback_info *usbif;
>> +    struct usbback_req *usbback_req;
>> +    unsigned int i;
>> +
>> +    TR_BUS("start\n");
>> +
>> +    usbback_disconnect(xendev);
>> +    usbif = container_of(xendev, struct usbback_info, xendev);
>> +    for (i = 1; i <= usbif->num_ports; i++) {
>> +        usbback_portid_remove(usbif, i);
>> +    }
> 
> You also need:
>       for (i=0; i < USBBACK_MAXPORTS; i++) {
>               p = &(usbif->ports[i].port);
>               usb_unregister_port(&usbif->bus, p);
>       }
> 
> I think?

Hmm, you might be right.

>> +
>> +    while (!QTAILQ_EMPTY(&usbif->req_free_q)) {
>> +        usbback_req = QTAILQ_FIRST(&usbif->req_free_q);
>> +        QTAILQ_REMOVE(&usbif->req_free_q, usbback_req, q);
>> +        g_free(usbback_req);
>> +    }
>> +
>> +    qemu_bh_delete(usbif->bh);
>> +
>> +    usb_bus_release(&usbif->bus);
>> +
>> +    TR_BUS("finished\n");
>> +
>> +    return 0;
>> +}
>> +
>> +static void usbback_event(struct XenDevice *xendev)
>> +{
>> +    struct usbback_info *usbif;
>> +
>> +    usbif = container_of(xendev, struct usbback_info, xendev);
>> +    qemu_bh_schedule(usbif->bh);
>> +}
>> +
>> +struct XenDevOps xen_usb_ops = {
>> +    .size            = sizeof(struct usbback_info),
>> +    .flags           = DEVOPS_FLAG_NEED_GNTDEV,
>> +    .init            = usbback_init,
>> +    .alloc           = usbback_alloc,
>> +    .free            = usbback_free,
>> +    .backend_changed = usbback_backend_changed,
>> +    .initialise      = usbback_connect,
>> +    .disconnect      = usbback_disconnect,
>> +    .event           = usbback_event,
>> +};
>> diff --git a/hw/xenpv/xen_machine_pv.c b/hw/xenpv/xen_machine_pv.c
>> index 57bc071..fef1e7b 100644
>> --- a/hw/xenpv/xen_machine_pv.c
>> +++ b/hw/xenpv/xen_machine_pv.c
>> @@ -72,6 +72,9 @@ static void xen_init_pv(MachineState *machine)
>>      xen_be_register("vfb", &xen_framebuffer_ops);
>>      xen_be_register("qdisk", &xen_blkdev_ops);
>>      xen_be_register("qnic", &xen_netdev_ops);
>> +#ifdef CONFIG_USB_LIBUSB
>> +    xen_be_register("qusb", &xen_usb_ops);
>> +#endif
>>  
>>      /* configure framebuffer */
>>      if (xenfb_enabled) {
>> diff --git a/include/hw/xen/xen_backend.h b/include/hw/xen/xen_backend.h
>> index f194aae..3d44dec 100644
>> --- a/include/hw/xen/xen_backend.h
>> +++ b/include/hw/xen/xen_backend.h
>> @@ -4,6 +4,10 @@
>>  #include "hw/xen/xen_common.h"
>>  #include "sysemu/sysemu.h"
>>  #include "net/net.h"
>> +#ifdef CONFIG_USB_LIBUSB
>> +#include <libusb.h>
>> +#include "hw/usb.h"
>> +#endif
>>  
>>  /* ------------------------------------------------------------- */
>>  
>> @@ -55,9 +59,6 @@ struct XenDevice {
>>  
>>  /* ------------------------------------------------------------- */
>>  
>> -#define usbback_get_packets(p) 0
>> -#define usbback_set_iso_desc(p, xfer)
>> -
>>  /* variables */
>>  extern XenXC xen_xc;
>>  extern struct xs_handle *xenstore;
>> @@ -101,6 +102,12 @@ extern struct XenDevOps xen_kbdmouse_ops;     /* 
>> xen_framebuffer.c */
>>  extern struct XenDevOps xen_framebuffer_ops;  /* xen_framebuffer.c */
>>  extern struct XenDevOps xen_blkdev_ops;       /* xen_disk.c        */
>>  extern struct XenDevOps xen_netdev_ops;       /* xen_nic.c         */
>> +#ifdef CONFIG_USB_LIBUSB
>> +extern struct XenDevOps xen_usb_ops;          /* xen-usb.c         */
>> +
>> +int usbback_get_packets(USBPacket *p);
>> +void usbback_set_iso_desc(USBPacket *p, struct libusb_transfer *xfer);
>> +#endif
>>  
>>  void xen_init_display(int domid);
>>  
>> -- 
>> 2.1.4
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> address@hidden
>> http://lists.xen.org/xen-devel
> 
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