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Re: [Qemu-devel] [PATCH v2 5/6] vhost-user: add slave-req-fd support
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/6] vhost-user: add slave-req-fd support |
Date: |
Tue, 30 May 2017 21:17:02 +0300 |
On Fri, May 26, 2017 at 04:28:57PM +0200, Maxime Coquelin wrote:
> From: Marc-André Lureau <address@hidden>
>
> Learn to give a socket to the slave to let him make requests to the
> master.
>
> Signed-off-by: Marc-André Lureau <address@hidden>
> Signed-off-by: Maxime Coquelin <address@hidden>
> ---
> docs/specs/vhost-user.txt | 32 +++++++++++-
> hw/virtio/vhost-user.c | 127
> ++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 157 insertions(+), 2 deletions(-)
>
> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> index 036890f..5fa7016 100644
> --- a/docs/specs/vhost-user.txt
> +++ b/docs/specs/vhost-user.txt
> @@ -139,6 +139,7 @@ in the ancillary data:
> * VHOST_USER_SET_VRING_KICK
> * VHOST_USER_SET_VRING_CALL
> * VHOST_USER_SET_VRING_ERR
> + * VHOST_USER_SET_SLAVE_REQ_FD
>
> If Master is unable to send the full message or receives a wrong reply it
> will
> close the connection. An optional reconnection mechanism can be implemented.
> @@ -252,6 +253,18 @@ Once the source has finished migration, rings will be
> stopped by
> the source. No further update must be done before rings are
> restarted.
>
> +Slave communication
> +-------------------
> +
> +An optional communication channel is provided if the slave declares
> +VHOST_USER_PROTOCOL_F_SLAVE_REQ protocol feature, to allow the slave to make
> +requests to the master.
> +
> +The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data.
> +
> +A slave may then send VHOST_USER_SLAVE_* messages to the master
> +using this fd communication channel.
> +
> Protocol features
> -----------------
>
> @@ -260,9 +273,10 @@ Protocol features
> #define VHOST_USER_PROTOCOL_F_RARP 2
> #define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
> #define VHOST_USER_PROTOCOL_F_MTU 4
> +#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
>
> -Message types
> --------------
> +Master message types
> +--------------------
>
> * VHOST_USER_GET_FEATURES
>
So down the road, we should make sure a device without
VHOST_USER_PROTOCOL_F_SLAVE_REQ does not advertise IOMMU
since you don't handle these messages otherwise.
> @@ -486,6 +500,20 @@ Message types
> If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
> with zero in case the specified MTU is valid, or non-zero otherwise.
>
> + * VHOST_USER_SET_SLAVE_REQ_FD
> +
> + Id: 21
> + Equivalent ioctl: N/A
> + Master payload: N/A
> +
> + Set the socket file descriptor for slave initiated requests. It is
> passed
> + in the ancillary data.
> + This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES
> + has been negotiated, and protocol feature bit
> VHOST_USER_PROTOCOL_F_SLAVE_REQ
> + bit is present in VHOST_USER_GET_PROTOCOL_FEATURES.
> + If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
> + with zero for success, non-zero otherwise.
> +
> VHOST_USER_PROTOCOL_F_REPLY_ACK:
> -------------------------------
> The original vhost-user specification only demands replies for certain
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 8a602e0..ea988fe 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -32,6 +32,7 @@ enum VhostUserProtocolFeature {
> VHOST_USER_PROTOCOL_F_RARP = 2,
> VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
> VHOST_USER_PROTOCOL_F_NET_MTU = 4,
> + VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
>
> VHOST_USER_PROTOCOL_F_MAX
> };
> @@ -60,9 +61,15 @@ typedef enum VhostUserRequest {
> VHOST_USER_SET_VRING_ENABLE = 18,
> VHOST_USER_SEND_RARP = 19,
> VHOST_USER_NET_SET_MTU = 20,
> + VHOST_USER_SET_SLAVE_REQ_FD = 21,
> VHOST_USER_MAX
> } VhostUserRequest;
>
> +typedef enum VhostUserSlaveRequest {
> + VHOST_USER_SLAVE_NONE = 0,
> + VHOST_USER_SLAVE_MAX
> +} VhostUserSlaveRequest;
> +
> typedef struct VhostUserMemoryRegion {
> uint64_t guest_phys_addr;
> uint64_t memory_size;
> @@ -112,6 +119,7 @@ static VhostUserMsg m __attribute__ ((unused));
>
> struct vhost_user {
> CharBackend *chr;
> + int slave_fd;
> };
>
> static bool ioeventfd_enabled(void)
> @@ -578,6 +586,115 @@ static int vhost_user_reset_device(struct vhost_dev
> *dev)
> return 0;
> }
>
> +static void slave_read(void *opaque)
> +{
> + struct vhost_dev *dev = opaque;
> + struct vhost_user *u = dev->opaque;
> + VhostUserMsg msg = { 0, };
> + int size, ret = 0;
> +
> + /* Read header */
> + size = read(u->slave_fd, &msg, VHOST_USER_HDR_SIZE);
> + if (size != VHOST_USER_HDR_SIZE) {
> + error_report("Failed to read from slave.");
> + goto err;
> + }
> +
> + if (msg.size > VHOST_USER_PAYLOAD_SIZE) {
> + error_report("Failed to read msg header."
> + " Size %d exceeds the maximum %zu.", msg.size,
> + VHOST_USER_PAYLOAD_SIZE);
> + goto err;
> + }
> +
> + /* Read payload */
> + size = read(u->slave_fd, &msg.payload, msg.size);
> + if (size != msg.size) {
> + error_report("Failed to read payload from slave.");
> + goto err;
> + }
> +
> + switch (msg.request) {
> + default:
> + error_report("Received unexpected msg type.");
> + ret = -EINVAL;
> + }
> +
> + /*
> + * REPLY_ACK feature handling. Other reply types has to be managed
> + * directly in their request handlers.
> + */
> + if (msg.flags & VHOST_USER_NEED_REPLY_MASK) {
> + msg.flags &= ~VHOST_USER_NEED_REPLY_MASK;
> + msg.flags |= VHOST_USER_REPLY_MASK;
> +
> + msg.payload.u64 = !!ret;
> + msg.size = sizeof(msg.payload.u64);
> +
> + size = write(u->slave_fd, &msg, VHOST_USER_HDR_SIZE + msg.size);
> + if (size != VHOST_USER_HDR_SIZE + msg.size) {
> + error_report("Failed to send msg reply to slave.");
> + goto err;
> + }
> + }
> +
> + return;
> +
> +err:
> + qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
> + close(u->slave_fd);
> + u->slave_fd = -1;
> + return;
> +}
> +
> +static int vhost_setup_slave_channel(struct vhost_dev *dev)
> +{
> + VhostUserMsg msg = {
> + .request = VHOST_USER_SET_SLAVE_REQ_FD,
> + .flags = VHOST_USER_VERSION,
> + };
> + struct vhost_user *u = dev->opaque;
> + int sv[2], ret = 0;
> + bool reply_supported = virtio_has_feature(dev->protocol_features,
> +
> VHOST_USER_PROTOCOL_F_REPLY_ACK);
> +
> + if (!virtio_has_feature(dev->protocol_features,
> + VHOST_USER_PROTOCOL_F_SLAVE_REQ)) {
> + return 0;
> + }
> +
> + if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
> + error_report("socketpair() failed");
> + return -1;
> + }
> +
> + u->slave_fd = sv[0];
> + qemu_set_fd_handler(u->slave_fd, slave_read, NULL, dev);
> +
> + if (reply_supported) {
> + msg.flags |= VHOST_USER_NEED_REPLY_MASK;
> + }
> +
> + ret = vhost_user_write(dev, &msg, &sv[1], 1);
> + if (ret) {
> + goto out;
> + }
> +
> + if (reply_supported) {
> + ret = process_message_reply(dev, msg);
> + }
> +
> +out:
> + close(sv[1]);
> + if (ret) {
> + qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
> + close(u->slave_fd);
> + u->slave_fd = -1;
> + }
> +
> + return ret;
> +}
> +
> static int vhost_user_init(struct vhost_dev *dev, void *opaque)
> {
> uint64_t features;
> @@ -588,6 +705,7 @@ static int vhost_user_init(struct vhost_dev *dev, void
> *opaque)
>
> u = g_new0(struct vhost_user, 1);
> u->chr = opaque;
> + u->slave_fd = -1;
> dev->opaque = u;
>
> err = vhost_user_get_features(dev, &features);
> @@ -628,6 +746,11 @@ static int vhost_user_init(struct vhost_dev *dev, void
> *opaque)
> "VHOST_USER_PROTOCOL_F_LOG_SHMFD feature.");
> }
>
> + err = vhost_setup_slave_channel(dev);
> + if (err < 0) {
> + return err;
> + }
> +
> return 0;
> }
>
> @@ -638,6 +761,10 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
> assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
>
> u = dev->opaque;
> + if (u->slave_fd >= 0) {
> + close(u->slave_fd);
> + u->slave_fd = -1;
> + }
> g_free(u);
> dev->opaque = 0;
>
> --
> 2.9.4
- [Qemu-devel] [PATCH v2 1/6] vhost: propagate errors in vhost_device_iotlb_miss(), (continued)
[Qemu-devel] [PATCH v2 4/6] vhost-user: add vhost_user to hold the chr, Maxime Coquelin, 2017/05/26
[Qemu-devel] [PATCH v2 5/6] vhost-user: add slave-req-fd support, Maxime Coquelin, 2017/05/26
- Re: [Qemu-devel] [PATCH v2 5/6] vhost-user: add slave-req-fd support,
Michael S. Tsirkin <=
[Qemu-devel] [PATCH v2 6/6] spec/vhost-user spec: Add IOMMU support, Maxime Coquelin, 2017/05/26
Re: [Qemu-devel] [PATCH v2 0/6] vhost-user: Specify and implement device IOTLB support, Maxime Coquelin, 2017/05/30
Re: [Qemu-devel] [PATCH v2 0/6] vhost-user: Specify and implement device IOTLB support, Michael S. Tsirkin, 2017/05/30