Re: [dpdk-dev] [PATCH 05/21] vhost: add support to slave requests channel

[Maxime Coquelin]

On 09/05/2017 06:19 AM, Tiwei Bie wrote:

On Thu, Aug 31, 2017 at 11:50:07AM +0200, Maxime Coquelin wrote:

Currently, only QEMU sends requests, the backend sends
replies. In some cases, the backend may need to send
requests to QEMU, like IOTLB miss events when IOMMU is
supported.

This patch introduces a new channel for such requests.
QEMU sends a file descriptor of a new socket using
VHOST_USER_SET_SLAVE_REQ_FD.

Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
---
  lib/librte_vhost/vhost.h      |  2 ++
  lib/librte_vhost/vhost_user.c | 27 +++++++++++++++++++++++++++
  lib/librte_vhost/vhost_user.h | 10 +++++++++-
  3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 18ad69c85..2340b0c2a 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -196,6 +196,8 @@ struct virtio_net {
        uint32_t                nr_guest_pages;
        uint32_t                max_guest_pages;
        struct guest_page       *guest_pages;
+
+       int                     slave_req_fd;
  } __rte_cache_aligned;

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c

index 8984dcb6a..7b3c2f32a 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -76,6 +76,7 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
        [VHOST_USER_SET_VRING_ENABLE]  = "VHOST_USER_SET_VRING_ENABLE",
        [VHOST_USER_SEND_RARP]  = "VHOST_USER_SEND_RARP",
        [VHOST_USER_NET_SET_MTU]  = "VHOST_USER_NET_SET_MTU",
+       [VHOST_USER_SET_SLAVE_REQ_FD]  = "VHOST_USER_SET_SLAVE_REQ_FD",
  };

static uint64_t

@@ -122,6 +123,11 @@ vhost_backend_cleanup(struct virtio_net *dev)
                munmap((void *)(uintptr_t)dev->log_addr, dev->log_size);
                dev->log_addr = 0;
        }
+
+       if (dev->slave_req_fd >= 0) {
+               close(dev->slave_req_fd);
+               dev->slave_req_fd = -1;

The slave_req_fd should also be initialized to -1 when allocating
the virtio_net structure. Currently, it's missing.

Good catch, thanks for spotting this.

Maxime

Best regards,
Tiwei Bie