€•¸g      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ'/translations/zh_CN/userspace-api/vduse”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ'/translations/zh_TW/userspace-api/vduse”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ'/translations/it_IT/userspace-api/vduse”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ'/translations/ja_JP/userspace-api/vduse”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ'/translations/ko_KR/userspace-api/vduse”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ'/translations/sp_SP/userspace-api/vduse”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒ"VDUSE - "vDPA Device in Userspace"”h]”hŒ&VDUSE - â€œvDPA Device in Userspaceâ€”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒA/var/lib/git/docbuild/linux/Documentation/userspace-api/vduse.rst”h KubhŒ	paragraph”“”)”}”(hXÿ  vDPA (virtio data path acceleration) device is a device that uses a
datapath which complies with the virtio specifications with vendor
specific control path. vDPA devices can be both physically located on
the hardware or emulated by software. VDUSE is a framework that makes it
possible to implement software-emulated vDPA devices in userspace. And
to make the device emulation more secure, the emulated vDPA device's
control path is handled in the kernel and only the data path is
implemented in the userspace.”h]”hX  vDPA (virtio data path acceleration) device is a device that uses a
datapath which complies with the virtio specifications with vendor
specific control path. vDPA devices can be both physically located on
the hardware or emulated by software. VDUSE is a framework that makes it
possible to implement software-emulated vDPA devices in userspace. And
to make the device emulation more secure, the emulated vDPA deviceâ€™s
control path is handled in the kernel and only the data path is
implemented in the userspace.”…””}”(hh¹hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hXM  Note that only virtio block device is supported by VDUSE framework now,
which can reduce security risks when the userspace process that implements
the data path is run by an unprivileged user. The support for other device
types can be added after the security issue of corresponding device driver
is clarified or fixed in the future.”h]”hXM  Note that only virtio block device is supported by VDUSE framework now,
which can reduce security risks when the userspace process that implements
the data path is run by an unprivileged user. The support for other device
types can be added after the security issue of corresponding device driver
is clarified or fixed in the future.”…””}”(hhÇhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¢)”}”(hhh]”(h§)”}”(hŒCreate/Destroy VDUSE devices”h]”hŒCreate/Destroy VDUSE devices”…””}”(hhØhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hhÕhžhhŸh¶h Kubh¸)”}”(hŒ%VDUSE devices are created as follows:”h]”hŒ%VDUSE devices are created as follows:”…””}”(hhæhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhhÕhžhubhŒenumerated_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒPCreate a new VDUSE instance with ioctl(VDUSE_CREATE_DEV) on
/dev/vduse/control.
”h]”h¸)”}”(hŒOCreate a new VDUSE instance with ioctl(VDUSE_CREATE_DEV) on
/dev/vduse/control.”h]”hŒOCreate a new VDUSE instance with ioctl(VDUSE_CREATE_DEV) on
/dev/vduse/control.”…””}”(hhÿhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khhûubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhhöhžhhŸh¶h Nubhú)”}”(hŒESetup each virtqueue with ioctl(VDUSE_VQ_SETUP) on /dev/vduse/$NAME.
”h]”h¸)”}”(hŒDSetup each virtqueue with ioctl(VDUSE_VQ_SETUP) on /dev/vduse/$NAME.”h]”hŒDSetup each virtqueue with ioctl(VDUSE_VQ_SETUP) on /dev/vduse/$NAME.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhhöhžhhŸh¶h Nubhú)”}”(hŒ†Begin processing VDUSE messages from /dev/vduse/$NAME. The first
messages will arrive while attaching the VDUSE instance to vDPA bus.
”h]”h¸)”}”(hŒ…Begin processing VDUSE messages from /dev/vduse/$NAME. The first
messages will arrive while attaching the VDUSE instance to vDPA bus.”h]”hŒ…Begin processing VDUSE messages from /dev/vduse/$NAME. The first
messages will arrive while attaching the VDUSE instance to vDPA bus.”…””}”(hj/  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj+  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhhöhžhhŸh¶h Nubhú)”}”(hŒTSend the VDPA_CMD_DEV_NEW netlink message to attach the VDUSE
instance to vDPA bus.
”h]”h¸)”}”(hŒSSend the VDPA_CMD_DEV_NEW netlink message to attach the VDUSE
instance to vDPA bus.”h]”hŒSSend the VDPA_CMD_DEV_NEW netlink message to attach the VDUSE
instance to vDPA bus.”…””}”(hjG  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K!hjC  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhhöhžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œenumtype”Œarabic”Œprefix”hŒsuffix”Œ.”uh1hôhhÕhžhhŸh¶h Kubh¸)”}”(hŒ'VDUSE devices are destroyed as follows:”h]”hŒ'VDUSE devices are destroyed as follows:”…””}”(hjf  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K$hhÕhžhubhõ)”}”(hhh]”(hú)”}”(hŒVSend the VDPA_CMD_DEV_DEL netlink message to detach the VDUSE
instance from vDPA bus.
”h]”h¸)”}”(hŒUSend the VDPA_CMD_DEV_DEL netlink message to detach the VDUSE
instance from vDPA bus.”h]”hŒUSend the VDPA_CMD_DEV_DEL netlink message to detach the VDUSE
instance from vDPA bus.”…””}”(hj{  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K&hjw  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhjt  hžhhŸh¶h Nubhú)”}”(hŒ9Close the file descriptor referring to /dev/vduse/$NAME.
”h]”h¸)”}”(hŒ8Close the file descriptor referring to /dev/vduse/$NAME.”h]”hŒ8Close the file descriptor referring to /dev/vduse/$NAME.”…””}”(hj“  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K)hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhjt  hžhhŸh¶h Nubhú)”}”(hŒPDestroy the VDUSE instance with ioctl(VDUSE_DESTROY_DEV) on
/dev/vduse/control.
”h]”h¸)”}”(hŒODestroy the VDUSE instance with ioctl(VDUSE_DESTROY_DEV) on
/dev/vduse/control.”h]”hŒODestroy the VDUSE instance with ioctl(VDUSE_DESTROY_DEV) on
/dev/vduse/control.”…””}”(hj«  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K+hj§  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhjt  hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”ja  jb  jc  hjd  je  uh1hôhhÕhžhhŸh¶h K&ubh¸)”}”(hŒYThe netlink messages can be sent via vdpa tool in iproute2 or use the
below sample codes:”h]”hŒYThe netlink messages can be sent via vdpa tool in iproute2 or use the
below sample codes:”…””}”(hjÅ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K.hhÕhžhubhŒliteral_block”“”)”}”(hX<  static int netlink_add_vduse(const char *name, enum vdpa_command cmd)
{
        struct nl_sock *nlsock;
        struct nl_msg *msg;
        int famid;

        nlsock = nl_socket_alloc();
        if (!nlsock)
                return -ENOMEM;

        if (genl_connect(nlsock))
                goto free_sock;

        famid = genl_ctrl_resolve(nlsock, VDPA_GENL_NAME);
        if (famid < 0)
                goto close_sock;

        msg = nlmsg_alloc();
        if (!msg)
                goto close_sock;

        if (!genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ, famid, 0, 0, cmd, 0))
                goto nla_put_failure;

        NLA_PUT_STRING(msg, VDPA_ATTR_DEV_NAME, name);
        if (cmd == VDPA_CMD_DEV_NEW)
                NLA_PUT_STRING(msg, VDPA_ATTR_MGMTDEV_DEV_NAME, "vduse");

        if (nl_send_sync(nlsock, msg))
                goto close_sock;

        nl_close(nlsock);
        nl_socket_free(nlsock);

        return 0;
nla_put_failure:
        nlmsg_free(msg);
close_sock:
        nl_close(nlsock);
free_sock:
        nl_socket_free(nlsock);
        return -1;
}”h]”hX<  static int netlink_add_vduse(const char *name, enum vdpa_command cmd)
{
        struct nl_sock *nlsock;
        struct nl_msg *msg;
        int famid;

        nlsock = nl_socket_alloc();
        if (!nlsock)
                return -ENOMEM;

        if (genl_connect(nlsock))
                goto free_sock;

        famid = genl_ctrl_resolve(nlsock, VDPA_GENL_NAME);
        if (famid < 0)
                goto close_sock;

        msg = nlmsg_alloc();
        if (!msg)
                goto close_sock;

        if (!genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ, famid, 0, 0, cmd, 0))
                goto nla_put_failure;

        NLA_PUT_STRING(msg, VDPA_ATTR_DEV_NAME, name);
        if (cmd == VDPA_CMD_DEV_NEW)
                NLA_PUT_STRING(msg, VDPA_ATTR_MGMTDEV_DEV_NAME, "vduse");

        if (nl_send_sync(nlsock, msg))
                goto close_sock;

        nl_close(nlsock);
        nl_socket_free(nlsock);

        return 0;
nla_put_failure:
        nlmsg_free(msg);
close_sock:
        nl_close(nlsock);
free_sock:
        nl_socket_free(nlsock);
        return -1;
}”…””}”hjÕ  sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”Œforce”‰Œlanguage”Œc”Œhighlight_args”}”uh1jÓ  hŸh¶h K1hhÕhžhubeh}”(h]”Œcreate-destroy-vduse-devices”ah ]”h"]”Œcreate/destroy vduse devices”ah$]”h&]”uh1h¡hh£hžhhŸh¶h Kubh¢)”}”(hhh]”(h§)”}”(hŒHow VDUSE works”h]”hŒHow VDUSE works”…””}”(hjõ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hjò  hžhhŸh¶h K`ubh¸)”}”(hX3  As mentioned above, a VDUSE device is created by ioctl(VDUSE_CREATE_DEV) on
/dev/vduse/control. With this ioctl, userspace can specify some basic configuration
such as device name (uniquely identify a VDUSE device), virtio features, virtio
configuration space, the number of virtqueues and so on for this emulated device.
Then a char device interface (/dev/vduse/$NAME) is exported to userspace for device
emulation. Userspace can use the VDUSE_VQ_SETUP ioctl on /dev/vduse/$NAME to
add per-virtqueue configuration such as the max size of virtqueue to the device.”h]”hX3  As mentioned above, a VDUSE device is created by ioctl(VDUSE_CREATE_DEV) on
/dev/vduse/control. With this ioctl, userspace can specify some basic configuration
such as device name (uniquely identify a VDUSE device), virtio features, virtio
configuration space, the number of virtqueues and so on for this emulated device.
Then a char device interface (/dev/vduse/$NAME) is exported to userspace for device
emulation. Userspace can use the VDUSE_VQ_SETUP ioctl on /dev/vduse/$NAME to
add per-virtqueue configuration such as the max size of virtqueue to the device.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kbhjò  hžhubh¸)”}”(hŒõAfter the initialization, the VDUSE device can be attached to vDPA bus via
the VDPA_CMD_DEV_NEW netlink message. Userspace needs to read()/write() on
/dev/vduse/$NAME to receive/reply some control messages from/to VDUSE kernel
module as follows:”h]”hŒõAfter the initialization, the VDUSE device can be attached to vDPA bus via
the VDPA_CMD_DEV_NEW netlink message. Userspace needs to read()/write() on
/dev/vduse/$NAME to receive/reply some control messages from/to VDUSE kernel
module as follows:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kjhjò  hžhubjÔ  )”}”(hX  static int vduse_message_handler(int dev_fd)
{
        int len;
        struct vduse_dev_request req;
        struct vduse_dev_response resp;

        len = read(dev_fd, &req, sizeof(req));
        if (len != sizeof(req))
                return -1;

        resp.request_id = req.request_id;

        switch (req.type) {

        /* handle different types of messages */

        }

        len = write(dev_fd, &resp, sizeof(resp));
        if (len != sizeof(resp))
                return -1;

        return 0;
}”h]”hX  static int vduse_message_handler(int dev_fd)
{
        int len;
        struct vduse_dev_request req;
        struct vduse_dev_response resp;

        len = read(dev_fd, &req, sizeof(req));
        if (len != sizeof(req))
                return -1;

        resp.request_id = req.request_id;

        switch (req.type) {

        /* handle different types of messages */

        }

        len = write(dev_fd, &resp, sizeof(resp));
        if (len != sizeof(resp))
                return -1;

        return 0;
}”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”jã  jä  jå  ‰jæ  jç  jè  }”uh1jÓ  hŸh¶h Kohjò  hžhubh¸)”}”(hŒDThere are now three types of messages introduced by VDUSE framework:”h]”hŒDThere are now three types of messages introduced by VDUSE framework:”…””}”(hj.  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KŠhjò  hžhubhŒbullet_list”“”)”}”(hhh]”(hú)”}”(hŒÄVDUSE_GET_VQ_STATE: Get the state for virtqueue, userspace should return
avail index for split virtqueue or the device/driver ring wrap counters and
the avail and used index for packed virtqueue.
”h]”h¸)”}”(hŒÃVDUSE_GET_VQ_STATE: Get the state for virtqueue, userspace should return
avail index for split virtqueue or the device/driver ring wrap counters and
the avail and used index for packed virtqueue.”h]”hŒÃVDUSE_GET_VQ_STATE: Get the state for virtqueue, userspace should return
avail index for split virtqueue or the device/driver ring wrap counters and
the avail and used index for packed virtqueue.”…””}”(hjE  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KŒhjA  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhj>  hžhhŸh¶h Nubhú)”}”(hXM  VDUSE_SET_STATUS: Set the device status, userspace should follow
the virtio spec: https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html
to process this message. For example, fail to set the FEATURES_OK device
status bit if the device can not accept the negotiated virtio features
get from the VDUSE_DEV_GET_FEATURES ioctl.
”h]”h¸)”}”(hXL  VDUSE_SET_STATUS: Set the device status, userspace should follow
the virtio spec: https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html
to process this message. For example, fail to set the FEATURES_OK device
status bit if the device can not accept the negotiated virtio features
get from the VDUSE_DEV_GET_FEATURES ioctl.”h]”(hŒRVDUSE_SET_STATUS: Set the device status, userspace should follow
the virtio spec: ”…””}”(hj]  hžhhŸNh NubhŒ	reference”“”)”}”(hŒ?https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html”h]”hŒ?https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html”…””}”(hjg  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”ji  uh1je  hj]  ubhŒ»
to process this message. For example, fail to set the FEATURES_OK device
status bit if the device can not accept the negotiated virtio features
get from the VDUSE_DEV_GET_FEATURES ioctl.”…””}”(hj]  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhjY  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhj>  hžhhŸh¶h Nubhú)”}”(hŒÊVDUSE_UPDATE_IOTLB: Notify userspace to update the memory mapping for specified
IOVA range, userspace should firstly remove the old mapping, then setup the new
mapping via the VDUSE_IOTLB_GET_FD ioctl.
”h]”h¸)”}”(hŒÉVDUSE_UPDATE_IOTLB: Notify userspace to update the memory mapping for specified
IOVA range, userspace should firstly remove the old mapping, then setup the new
mapping via the VDUSE_IOTLB_GET_FD ioctl.”h]”hŒÉVDUSE_UPDATE_IOTLB: Notify userspace to update the memory mapping for specified
IOVA range, userspace should firstly remove the old mapping, then setup the new
mapping via the VDUSE_IOTLB_GET_FD ioctl.”…””}”(hjŠ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K–hj†  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhj>  hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1j<  hŸh¶h KŒhjò  hžhubh¸)”}”(hŒƒAfter DRIVER_OK status bit is set via the VDUSE_SET_STATUS message, userspace is
able to start the dataplane processing as follows:”h]”hŒƒAfter DRIVER_OK status bit is set via the VDUSE_SET_STATUS message, userspace is
able to start the dataplane processing as follows:”…””}”(hj¦  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kšhjò  hžhubhõ)”}”(hhh]”(hú)”}”(hŒ½Get the specified virtqueue's information with the VDUSE_VQ_GET_INFO ioctl,
including the size, the IOVAs of descriptor table, available ring and used ring,
the state and the ready status.
”h]”h¸)”}”(hŒ¼Get the specified virtqueue's information with the VDUSE_VQ_GET_INFO ioctl,
including the size, the IOVAs of descriptor table, available ring and used ring,
the state and the ready status.”h]”hŒ¾Get the specified virtqueueâ€™s information with the VDUSE_VQ_GET_INFO ioctl,
including the size, the IOVAs of descriptor table, available ring and used ring,
the state and the ready status.”…””}”(hj»  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj·  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhj´  hžhhŸh¶h Nubhú)”}”(hŒPass the above IOVAs to the VDUSE_IOTLB_GET_FD ioctl so that those IOVA regions
can be mapped into userspace. Some sample codes is shown below:
”h]”h¸)”}”(hŒPass the above IOVAs to the VDUSE_IOTLB_GET_FD ioctl so that those IOVA regions
can be mapped into userspace. Some sample codes is shown below:”h]”hŒPass the above IOVAs to the VDUSE_IOTLB_GET_FD ioctl so that those IOVA regions
can be mapped into userspace. Some sample codes is shown below:”…””}”(hjÓ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K¡hjÏ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhj´  hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”ja  jb  jc  hjd  je  uh1hôhjò  hžhhŸh¶h KubjÔ  )”}”(hX×  static int perm_to_prot(uint8_t perm)
{
        int prot = 0;

        switch (perm) {
        case VDUSE_ACCESS_WO:
                prot |= PROT_WRITE;
                break;
        case VDUSE_ACCESS_RO:
                prot |= PROT_READ;
                break;
        case VDUSE_ACCESS_RW:
                prot |= PROT_READ | PROT_WRITE;
                break;
        }

        return prot;
}

static void *iova_to_va(int dev_fd, uint64_t iova, uint64_t *len)
{
        int fd;
        void *addr;
        size_t size;
        struct vduse_iotlb_entry entry;

        entry.start = iova;
        entry.last = iova;

        /*
         * Find the first IOVA region that overlaps with the specified
         * range [start, last] and return the corresponding file descriptor.
         */
        fd = ioctl(dev_fd, VDUSE_IOTLB_GET_FD, &entry);
        if (fd < 0)
                return NULL;

        size = entry.last - entry.start + 1;
        *len = entry.last - iova + 1;
        addr = mmap(0, size, perm_to_prot(entry.perm), MAP_SHARED,
                    fd, entry.offset);
        close(fd);
        if (addr == MAP_FAILED)
                return NULL;

        /*
         * Using some data structures such as linked list to store
         * the iotlb mapping. The munmap(2) should be called for the
         * cached mapping when the corresponding VDUSE_UPDATE_IOTLB
         * message is received or the device is reset.
         */

        return addr + iova - entry.start;
}”h]”hX×  static int perm_to_prot(uint8_t perm)
{
        int prot = 0;

        switch (perm) {
        case VDUSE_ACCESS_WO:
                prot |= PROT_WRITE;
                break;
        case VDUSE_ACCESS_RO:
                prot |= PROT_READ;
                break;
        case VDUSE_ACCESS_RW:
                prot |= PROT_READ | PROT_WRITE;
                break;
        }

        return prot;
}

static void *iova_to_va(int dev_fd, uint64_t iova, uint64_t *len)
{
        int fd;
        void *addr;
        size_t size;
        struct vduse_iotlb_entry entry;

        entry.start = iova;
        entry.last = iova;

        /*
         * Find the first IOVA region that overlaps with the specified
         * range [start, last] and return the corresponding file descriptor.
         */
        fd = ioctl(dev_fd, VDUSE_IOTLB_GET_FD, &entry);
        if (fd < 0)
                return NULL;

        size = entry.last - entry.start + 1;
        *len = entry.last - iova + 1;
        addr = mmap(0, size, perm_to_prot(entry.perm), MAP_SHARED,
                    fd, entry.offset);
        close(fd);
        if (addr == MAP_FAILED)
                return NULL;

        /*
         * Using some data structures such as linked list to store
         * the iotlb mapping. The munmap(2) should be called for the
         * cached mapping when the corresponding VDUSE_UPDATE_IOTLB
         * message is received or the device is reset.
         */

        return addr + iova - entry.start;
}”…””}”hjí  sbah}”(h]”h ]”h"]”h$]”h&]”jã  jä  jå  ‰jæ  jç  jè  }”uh1jÓ  hŸh¶h K¤hjò  hžhubhõ)”}”(hhh]”(hú)”}”(hX  Setup the kick eventfd for the specified virtqueues with the VDUSE_VQ_SETUP_KICKFD
ioctl. The kick eventfd is used by VDUSE kernel module to notify userspace to
consume the available ring. This is optional since userspace can choose to poll the
available ring instead.
”h]”h¸)”}”(hX  Setup the kick eventfd for the specified virtqueues with the VDUSE_VQ_SETUP_KICKFD
ioctl. The kick eventfd is used by VDUSE kernel module to notify userspace to
consume the available ring. This is optional since userspace can choose to poll the
available ring instead.”h]”hX  Setup the kick eventfd for the specified virtqueues with the VDUSE_VQ_SETUP_KICKFD
ioctl. The kick eventfd is used by VDUSE kernel module to notify userspace to
consume the available ring. This is optional since userspace can choose to poll the
available ring instead.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KÝhjÿ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhjü  hžhhŸh¶h Nubhú)”}”(hŒÞListen to the kick eventfd (optional) and consume the available ring. The buffer
described by the descriptors in the descriptor table should be also mapped into
userspace via the VDUSE_IOTLB_GET_FD ioctl before accessing.
”h]”h¸)”}”(hŒÝListen to the kick eventfd (optional) and consume the available ring. The buffer
described by the descriptors in the descriptor table should be also mapped into
userspace via the VDUSE_IOTLB_GET_FD ioctl before accessing.”h]”hŒÝListen to the kick eventfd (optional) and consume the available ring. The buffer
described by the descriptors in the descriptor table should be also mapped into
userspace via the VDUSE_IOTLB_GET_FD ioctl before accessing.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kâhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhjü  hžhhŸh¶h Nubhú)”}”(hŒmInject an interrupt for specific virtqueue with the VDUSE_INJECT_VQ_IRQ ioctl
after the used ring is filled.
”h]”h¸)”}”(hŒlInject an interrupt for specific virtqueue with the VDUSE_INJECT_VQ_IRQ ioctl
after the used ring is filled.”h]”hŒlInject an interrupt for specific virtqueue with the VDUSE_INJECT_VQ_IRQ ioctl
after the used ring is filled.”…””}”(hj3  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kæhj/  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hùhjü  hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”ja  jb  jc  hjd  je  Œstart”Kuh1hôhjò  hžhhŸh¶h KÝubh¸)”}”(hŒDFor more details on the uAPI, please see include/uapi/linux/vduse.h.”h]”hŒDFor more details on the uAPI, please see include/uapi/linux/vduse.h.”…””}”(hjN  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kéhjò  hžhubeh}”(h]”Œhow-vduse-works”ah ]”h"]”Œhow vduse works”ah$]”h&]”uh1h¡hh£hžhhŸh¶h K`ubeh}”(h]”Œvduse-vdpa-device-in-userspace”ah ]”h"]”Œ"vduse - "vdpa device in userspace"”ah$]”h&]”uh1h¡hhhžhhŸh¶h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h¶uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¦NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”j  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h¶Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(ji  jf  jï  jì  ja  j^  uŒ	nametypes”}”(ji  ‰jï  ‰ja  ‰uh}”(jf  h£jì  hÕj^  jò  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”hŒsystem_message”“”)”}”(hhh]”h¸)”}”(hŒ:Enumerated list start value not ordinal-1: "3" (ordinal 3)”h]”hŒ>Enumerated list start value not ordinal-1: â€œ3â€ (ordinal 3)”…””}”(hjö  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hjó  ubah}”(h]”h ]”h"]”h$]”h&]”Œlevel”KŒtype”ŒINFO”Œsource”h¶Œline”Kuh1jñ  hjò  hžhhŸh¶h KÝubaŒtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.