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Blame SOURCES/kvm-vhost-user-allow-slave-to-send-fds-via-slave-channel.patch

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From 6fceacad0e3d27cec6cef4e105c1dabacccb875c Mon Sep 17 00:00:00 2001
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From: "plai@redhat.com" <plai@redhat.com>
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Date: Thu, 21 Jun 2018 18:54:42 +0200
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Subject: [PATCH 163/268] vhost-user: allow slave to send fds via slave channel
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RH-Author: plai@redhat.com
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Message-id: <1529607285-9942-8-git-send-email-plai@redhat.com>
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Patchwork-id: 80935
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O-Subject: [RHEL7.6 PATCH BZ 1526645 07/10] vhost-user: allow slave to send fds via slave channel
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Bugzilla: 1526645
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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RH-Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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From: Tiwei Bie <tiwei.bie@intel.com>
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Introduce VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD protocol
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feature to allow slave to send at most 8 descriptors
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in each message to master via ancillary data using the
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slave channel.
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Suggested-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit 5f57fbeaaf7c4cd33152d7f2e449caab4d4209d9)
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Signed-off-by: Paul Lai <plai@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 docs/interop/vhost-user.txt |  5 +++++
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 hw/virtio/vhost-user.c      | 27 +++++++++++++++++----------
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 2 files changed, 22 insertions(+), 10 deletions(-)
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diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
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index 534caab..682a683 100644
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--- a/docs/interop/vhost-user.txt
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+++ b/docs/interop/vhost-user.txt
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@@ -367,6 +367,10 @@ The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data.
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 A slave may then send VHOST_USER_SLAVE_* messages to the master
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 using this fd communication channel.
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+If VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD protocol feature is negotiated,
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+slave can send file descriptors (at most 8 descriptors in each message)
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+to master via ancillary data using this fd communication channel.
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+
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 Protocol features
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 -----------------
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@@ -380,6 +384,7 @@ Protocol features
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 #define VHOST_USER_PROTOCOL_F_CRYPTO_SESSION 7
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 #define VHOST_USER_PROTOCOL_F_PAGEFAULT      8
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 #define VHOST_USER_PROTOCOL_F_CONFIG         9
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+#define VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD  10
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 Master message types
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 --------------------
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diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
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index ebb946a..e8027ad 100644
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--- a/hw/virtio/vhost-user.c
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+++ b/hw/virtio/vhost-user.c
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@@ -30,6 +30,7 @@
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 #define VHOST_MEMORY_MAX_NREGIONS    8
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 #define VHOST_USER_F_PROTOCOL_FEATURES 30
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+#define VHOST_USER_SLAVE_MAX_FDS     8
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 /*
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  * Maximum size of virtio device config space
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@@ -47,6 +48,7 @@ enum VhostUserProtocolFeature {
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     VHOST_USER_PROTOCOL_F_CRYPTO_SESSION = 7,
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     VHOST_USER_PROTOCOL_F_PAGEFAULT = 8,
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     VHOST_USER_PROTOCOL_F_CONFIG = 9,
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+    VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,
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     VHOST_USER_PROTOCOL_F_MAX
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 };
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@@ -854,10 +856,10 @@ static void slave_read(void *opaque)
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     int size, ret = 0;
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     struct iovec iov;
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     struct msghdr msgh;
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-    int fd = -1;
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+    int fd[VHOST_USER_SLAVE_MAX_FDS];
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     char control[CMSG_SPACE(sizeof(fd))];
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     struct cmsghdr *cmsg;
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-    size_t fdsize;
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+    int i, fdsize = 0;
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     memset(&msgh, 0, sizeof(msgh));
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     msgh.msg_iov = &iov;
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@@ -865,6 +867,8 @@ static void slave_read(void *opaque)
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     msgh.msg_control = control;
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     msgh.msg_controllen = sizeof(control);
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+    memset(fd, -1, sizeof(fd));
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+
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     /* Read header */
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     iov.iov_base = &hd;;
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     iov.iov_len = VHOST_USER_HDR_SIZE;
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@@ -885,7 +889,7 @@ static void slave_read(void *opaque)
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             if (cmsg->cmsg_level == SOL_SOCKET &&
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                 cmsg->cmsg_type == SCM_RIGHTS) {
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                     fdsize = cmsg->cmsg_len - CMSG_LEN(0);
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-                    memcpy(&fd, CMSG_DATA(cmsg), fdsize);
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+                    memcpy(fd, CMSG_DATA(cmsg), fdsize);
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                     break;
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             }
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     }
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@@ -913,14 +917,15 @@ static void slave_read(void *opaque)
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         break;
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     default:
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         error_report("Received unexpected msg type.");
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-        if (fd != -1) {
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-            close(fd);
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-        }
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         ret = -EINVAL;
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     }
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-    /* Message handlers need to make sure that fd will be consumed. */
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-    fd = -1;
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+    /* Close the remaining file descriptors. */
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+    for (i = 0; i < fdsize; i++) {
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+        if (fd[i] != -1) {
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+            close(fd[i]);
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+        }
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+    }
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     /*
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      * REPLY_ACK feature handling. Other reply types has to be managed
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@@ -954,8 +959,10 @@ err:
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     qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
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     close(u->slave_fd);
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     u->slave_fd = -1;
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-    if (fd != -1) {
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-        close(fd);
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+    for (i = 0; i < fdsize; i++) {
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+        if (fd[i] != -1) {
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+            close(fd[i]);
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+        }
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     }
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     return;
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 }
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-- 
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1.8.3.1
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