Re: [dpdk-dev] [PATCH 04/12] vhost: introduce postcopy's advise message

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 09/26/2018 05:22 PM, Alejandro Lucero wrote:
> 
> 
> On Wed, Sep 26, 2018 at 8:27 AM Maxime Coquelin 
> <maxime.coquelin@redhat.com <mailto:maxime.coquelin@redhat.com>> wrote:
> 
>     This patch opens a userfaultfd and sends it back to Qemu's
>     VHOST_USER_POSTCOPY_ADVISE request.
> 
>     Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com
>     <mailto:dgilbert@redhat.com>>
>     Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com
>     <mailto:maxime.coquelin@redhat.com>>
>     ---
>       lib/librte_vhost/vhost.h      |  2 ++
>       lib/librte_vhost/vhost_user.c | 37 +++++++++++++++++++++++++++++++++++
>       lib/librte_vhost/vhost_user.h |  3 ++-
>       3 files changed, 41 insertions(+), 1 deletion(-)
> 
>     diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
>     index 25ffd7614..21722d8a8 100644
>     --- a/lib/librte_vhost/vhost.h
>     +++ b/lib/librte_vhost/vhost.h
>     @@ -363,6 +363,8 @@ struct virtio_net {
>              int                     slave_req_fd;
>              rte_spinlock_t          slave_req_lock;
> 
>     +       int                     postcopy_ufd;
>     +
>              /*
>               * Device id to identify a specific backend device.
>               * It's set to -1 for the default software implementation.
>     diff --git a/lib/librte_vhost/vhost_user.c
>     b/lib/librte_vhost/vhost_user.c
>     index a9b429598..bdfe2cac0 100644
>     --- a/lib/librte_vhost/vhost_user.c
>     +++ b/lib/librte_vhost/vhost_user.c
>     @@ -24,9 +24,13 @@
>       #include <stdlib.h>
>       #include <string.h>
>       #include <unistd.h>
>     +#include <fcntl.h>
>     +#include <linux/userfaultfd.h>
>     +#include <sys/ioctl.h>
>       #include <sys/mman.h>
>       #include <sys/types.h>
>       #include <sys/stat.h>
>     +#include <sys/syscall.h>
>       #include <assert.h>
>       #ifdef RTE_LIBRTE_VHOST_NUMA
>       #include <numaif.h>
>     @@ -69,6 +73,7 @@ static const char
>     *vhost_message_str[VHOST_USER_MAX] = {
>              [VHOST_USER_IOTLB_MSG]  = "VHOST_USER_IOTLB_MSG",
>              [VHOST_USER_CRYPTO_CREATE_SESS] =
>     "VHOST_USER_CRYPTO_CREATE_SESS",
>              [VHOST_USER_CRYPTO_CLOSE_SESS] =
>     "VHOST_USER_CRYPTO_CLOSE_SESS",
>     +       [VHOST_USER_POSTCOPY_ADVISE]  = "VHOST_USER_POSTCOPY_ADVISE",
>       };
> 
>       static uint64_t
>     @@ -1412,6 +1417,33 @@ vhost_user_iotlb_msg(struct virtio_net
>     **pdev, struct VhostUserMsg *msg)
>              return 0;
>       }
> 
>     +static int
>     +vhost_user_set_postcopy_advise(struct virtio_net *dev, struct
>     VhostUserMsg *msg)
>     +{
>     +       struct uffdio_api api_struct;
>     +
>     +
>     +       dev->postcopy_ufd = syscall(__NR_userfaultfd, O_CLOEXEC |
>     O_NONBLOCK);
>     +
>     +       if (dev->postcopy_ufd == -1) {
>     +               RTE_LOG(ERR, VHOST_CONFIG, "Userfaultfd not
>     available: %s\n",
>     +                               strerror(errno));
>     +               return -1;
>     +       }
>     +       api_struct.api = UFFD_API;
>     +       api_struct.features = 0;
>     +       if (ioctl(dev->postcopy_ufd, UFFDIO_API, &api_struct)) {
>     +               RTE_LOG(ERR, VHOST_CONFIG, "UFFDIO_API ioctl
>     failure: %s\n",
>     +                               strerror(errno));
>     +               close(dev->postcopy_ufd);
>     +               return -1;
>     +       }
>     +       msg->fds[0] = dev->postcopy_ufd;
>     +       msg->fd_num = 1;
>     +
>     +       return 0;
>     +}
>     +
>       /* return bytes# of read on success or negative val on failure. */
>       static int
>       read_vhost_message(int sockfd, struct VhostUserMsg *msg)
>     @@ -1756,6 +1788,11 @@ vhost_user_msg_handler(int vid, int fd)
>                      ret = vhost_user_iotlb_msg(&dev, &msg);
>                      break;
> 
>     +       case VHOST_USER_POSTCOPY_ADVISE:
>     +               vhost_user_set_postcopy_advise(dev, &msg);
>     +               send_vhost_reply(fd, &msg);
>     +               break;
>     +
> 
> 
> This should handle the case of vhost_user_set_postcopy_advise returning 
> an error. Otherwise the msg wrong contents are sent back.

Right, I'll fix it when rebasing.

> 
>              default:
>                      ret = -1;
>                      break;
>     diff --git a/lib/librte_vhost/vhost_user.h
>     b/lib/librte_vhost/vhost_user.h
>     index dd0262f8f..2030b40a5 100644
>     --- a/lib/librte_vhost/vhost_user.h
>     +++ b/lib/librte_vhost/vhost_user.h
>     @@ -50,7 +50,8 @@ typedef enum VhostUserRequest {
>              VHOST_USER_IOTLB_MSG = 22,
>              VHOST_USER_CRYPTO_CREATE_SESS = 26,
>              VHOST_USER_CRYPTO_CLOSE_SESS = 27,
>     -       VHOST_USER_MAX = 28
>     +       VHOST_USER_POSTCOPY_ADVISE = 28,
>     +       VHOST_USER_MAX = 29
>       } VhostUserRequest;
> 
>       typedef enum VhostUserSlaveRequest {
>     -- 
>     2.17.1
> 

Thanks,
Maxime