Re: [Qemu-devel] [PATCH v8 3/4] contrib/libvhost-user: enable virtio config space messages

[Liu, Changpeng]

> -----Original Message-----
> From: Marc-André Lureau [mailto:address@hidden
> Sent: Tuesday, January 2, 2018 11:30 PM
> To: Liu, Changpeng <address@hidden>
> Cc: QEMU <address@hidden>; Harris, James R <address@hidden>;
> Michael S. Tsirkin <address@hidden>; Stefan Hajnoczi <address@hidden>;
> Paolo Bonzini <address@hidden>; Felipe Franciosi <address@hidden>
> Subject: Re: [Qemu-devel] [PATCH v8 3/4] contrib/libvhost-user: enable virtio
> config space messages
> 
> Hi
> 
> On Tue, Jan 2, 2018 at 4:55 AM, Changpeng Liu <address@hidden> wrote:
> > Enable VHOST_USER_GET_CONFIG/VHOST_USER_SET_CONFIG messages in
> > libvhost-user library, users can implement their own I/O target
> > based on the library. This enable the virtio config space delivered
> > between QEMU host device and the I/O target.
> >
> > Signed-off-by: Changpeng Liu <address@hidden>
> > ---
> >  contrib/libvhost-user/libvhost-user.c | 54
> +++++++++++++++++++++++++++++++++++
> >  contrib/libvhost-user/libvhost-user.h | 34 +++++++++++++++++++++-
> >  2 files changed, 87 insertions(+), 1 deletion(-)
> >
> > diff --git a/contrib/libvhost-user/libvhost-user.c 
> > b/contrib/libvhost-user/libvhost-
> user.c
> > index f409bd3..9e12eb1 100644
> > --- a/contrib/libvhost-user/libvhost-user.c
> > +++ b/contrib/libvhost-user/libvhost-user.c
> > @@ -84,6 +84,8 @@ vu_request_to_string(unsigned int req)
> >          REQ(VHOST_USER_SET_SLAVE_REQ_FD),
> >          REQ(VHOST_USER_IOTLB_MSG),
> >          REQ(VHOST_USER_SET_VRING_ENDIAN),
> > +        REQ(VHOST_USER_GET_CONFIG),
> > +        REQ(VHOST_USER_SET_CONFIG),
> >          REQ(VHOST_USER_MAX),
> >      };
> >  #undef REQ
> > @@ -798,6 +800,53 @@ vu_set_slave_req_fd(VuDev *dev, VhostUserMsg *vmsg)
> >  }
> >
> >  static bool
> > +vu_get_config(VuDev *dev, VhostUserMsg *vmsg)
> > +{
> > +    int ret = -1;
> > +
> > +    if (dev->iface->get_config) {
> > +        ret = dev->iface->get_config(dev, vmsg->payload.config.region,
> > +                                     vmsg->payload.config.size);
> > +    }
> > +
> > +    if (ret) {
> > +        /* resize to zero to indicate an error to master */
> > +        vmsg->size = 0;
> > +    }
> > +
> > +    return true;
> > +}
> > +
> > +static bool
> > +vu_set_config(VuDev *dev, VhostUserMsg *vmsg)
> > +{
> > +    int ret = -1;
> > +    bool reply_supported = !!(dev->protocol_features &
> > +                             (1ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK));
> > +
> 
> None of the other messages in libvhost-user support the REPLY_ACK
> flag. Do you need it? If not, please drop it.
Ok, will drop it.
> 
> If you need it, it's a better idea to make the reply explicit and
> mandatory in the protocol for SET_CONFIG.
> 
> > +    if (dev->iface->set_config) {
> > +        ret = dev->iface->set_config(dev, vmsg->payload.config.region,
> > +                                     vmsg->payload.config.offset,
> > +                                     vmsg->payload.config.size,
> > +                                     vmsg->payload.config.flags);
> > +    }
> > +
> > +    vmsg->size = sizeof(vmsg->payload.u64);
> > +    if (!ret) {
> > +        vmsg->payload.u64 = 0;
> > +    } else {
> > +        /* indicate an error in case reply supported */
> > +        vmsg->payload.u64 = 1;
> > +    }
> > +
> > +    if (reply_supported) {
> > +        return true;
> > +    }
> > +
> > +    return false;
> > +}
> > +
> > +static bool
> >  vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
> >  {
> >      int do_reply = 0;
> > @@ -862,6 +911,10 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
> >          return vu_set_vring_enable_exec(dev, vmsg);
> >      case VHOST_USER_SET_SLAVE_REQ_FD:
> >          return vu_set_slave_req_fd(dev, vmsg);
> > +    case VHOST_USER_GET_CONFIG:
> > +        return vu_get_config(dev, vmsg);
> > +    case VHOST_USER_SET_CONFIG:
> > +        return vu_set_config(dev, vmsg);
> >      case VHOST_USER_NONE:
> >          break;
> >      default:
> > @@ -970,6 +1023,7 @@ vu_init(VuDev *dev,
> >      dev->iface = iface;
> >      dev->log_call_fd = -1;
> >      dev->slave_fd = -1;
> > +
> 
> unrelated coding style change, please drop
Thanks.
> 
> >      for (i = 0; i < VHOST_MAX_NR_VIRTQUEUE; i++) {
> >          dev->vq[i] = (VuVirtq) {
> >              .call_fd = -1, .kick_fd = -1, .err_fd = -1,
> > diff --git a/contrib/libvhost-user/libvhost-user.h 
> > b/contrib/libvhost-user/libvhost-
> user.h
> > index 2f5864b..b38959e 100644
> > --- a/contrib/libvhost-user/libvhost-user.h
> > +++ b/contrib/libvhost-user/libvhost-user.h
> > @@ -30,6 +30,16 @@
> >
> >  #define VHOST_MEMORY_MAX_NREGIONS 8
> >
> > +typedef enum VhostSetConfigType {
> > +    VHOST_SET_CONFIG_TYPE_MASTER = 0,
> > +    VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
> > +} VhostSetConfigType;
> > +
> > +/*
> > + * Maximum size of virtio device config space
> > + */
> > +#define VHOST_USER_MAX_CONFIG_SIZE 256
> > +
> >  enum VhostUserProtocolFeature {
> >      VHOST_USER_PROTOCOL_F_MQ = 0,
> >      VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
> > @@ -38,7 +48,6 @@ enum VhostUserProtocolFeature {
> >      VHOST_USER_PROTOCOL_F_NET_MTU = 4,
> >      VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
> >      VHOST_USER_PROTOCOL_F_CROSS_ENDIAN = 6,
> > -
> 
> 
> unrelated coding style change, please drop
Thanks.
> 
> >      VHOST_USER_PROTOCOL_F_MAX
> >  };
> >
> > @@ -69,6 +78,8 @@ typedef enum VhostUserRequest {
> >      VHOST_USER_SET_SLAVE_REQ_FD = 21,
> >      VHOST_USER_IOTLB_MSG = 22,
> >      VHOST_USER_SET_VRING_ENDIAN = 23,
> > +    VHOST_USER_GET_CONFIG = 24,
> > +    VHOST_USER_SET_CONFIG = 25,
> >      VHOST_USER_MAX
> >  } VhostUserRequest;
> >
> > @@ -90,6 +101,18 @@ typedef struct VhostUserLog {
> >      uint64_t mmap_offset;
> >  } VhostUserLog;
> >
> > +typedef struct VhostUserConfig {
> > +    uint32_t offset;
> > +    uint32_t size;
> > +    uint32_t flags;
> > +    uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
> > +} VhostUserConfig;
> > +
> > +static VhostUserConfig c __attribute__ ((unused));
> > +#define VHOST_USER_CONFIG_HDR_SIZE (sizeof(c.offset) \
> > +                                   + sizeof(c.size) \
> > +                                   + sizeof(c.flags))
> > +
> >  #if defined(_WIN32)
> >  # define VU_PACKED __attribute__((gcc_struct, packed))
> >  #else
> > @@ -112,6 +135,7 @@ typedef struct VhostUserMsg {
> >          struct vhost_vring_addr addr;
> >          VhostUserMemory memory;
> >          VhostUserLog log;
> > +        VhostUserConfig config;
> >      } payload;
> >
> >      int fds[VHOST_MEMORY_MAX_NREGIONS];
> > @@ -140,6 +164,10 @@ typedef int (*vu_process_msg_cb) (VuDev *dev,
> VhostUserMsg *vmsg,
> >                                    int *do_reply);
> >  typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool 
> > started);
> >  typedef bool (*vu_queue_is_processed_in_order_cb) (VuDev *dev, int qidx);
> > +typedef int (*vu_get_config_cb) (VuDev *dev, uint8_t *config, uint32_t 
> > len);
> > +typedef int (*vu_set_config_cb) (VuDev *dev, const uint8_t *data,
> > +                                 uint32_t offset, uint32_t size,
> > +                                 uint32_t flags);
> >
> >  typedef struct VuDevIface {
> >      /* called by VHOST_USER_GET_FEATURES to get the features bitmask */
> > @@ -162,6 +190,10 @@ typedef struct VuDevIface {
> >       * on unmanaged exit/crash.
> >       */
> >      vu_queue_is_processed_in_order_cb queue_is_processed_in_order;
> > +    /* get the config space of the device */
> > +    vu_get_config_cb get_config;
> > +    /* set the config space of the device */
> > +    vu_set_config_cb set_config;
> >  } VuDevIface;
> >
> >  typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);
> > --
> > 1.9.3
> >
> 
> 
> --
> Marc-André Lureau