Create a new vsock endpoint by opening /dev/vhost-vsock,
set the requested CID via ioctl (or assign a free one if auto='yes'),
pass the file descriptor to QEMU and build the command line.

https://bugzilla.redhat.com/show_bug.cgi?id=1291851
Signed-off-by: Ján Tomko <jtomko@redhat.com>
---
Rebased version with all the ACKed squash-ins for patches 1-6 available at:
git://repo.or.cz/libvirt/jtomko.git vsock-v3
http://repo.or.cz/libvirt/jtomko.git/shortlog/refs/heads/vsock-v3

 src/qemu/qemu_alias.c                              | 16 +++++++++
 src/qemu/qemu_command.c                            | 40 ++++++++++++++++++++++
 src/qemu/qemu_domain.c                             |  5 +++
 src/qemu/qemu_domain.h                             |  2 +-
 src/qemu/qemu_process.c                            | 35 +++++++++++++++++++
 .../vhost-vsock-auto.x86_64-latest.args            | 32 +++++++++++++++++
 .../vhost-vsock.x86_64-latest.args                 | 32 +++++++++++++++++
 tests/qemuxml2argvtest.c                           | 14 ++++++++
 8 files changed, 175 insertions(+), 1 deletion(-)
 create mode 100644 tests/qemuxml2argvdata/vhost-vsock-auto.x86_64-latest.args
 create mode 100644 tests/qemuxml2argvdata/vhost-vsock.x86_64-latest.args

diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c
index 578a33b284..89dec91ed1 100644
--- a/src/qemu/qemu_alias.c
+++ b/src/qemu/qemu_alias.c
@@ -533,6 +533,18 @@ qemuAssignDeviceInputAlias(virDomainDefPtr def,
 }
 
 
+static int
+qemuAssignDeviceVsockAlias(virDomainVsockDefPtr vsock)
+{
+    if (vsock->info.alias)
+        return 0;
+    if (VIR_STRDUP(vsock->info.alias, "vsock0") < 0)
+        return -1;
+
+    return 0;
+}
+
+
 int
 qemuAssignDeviceAliases(virDomainDefPtr def, virQEMUCapsPtr qemuCaps)
 {
@@ -629,6 +641,10 @@ qemuAssignDeviceAliases(virDomainDefPtr def, virQEMUCapsPtr qemuCaps)
         if (qemuAssignDeviceMemoryAlias(NULL, def->mems[i], false) < 0)
             return -1;
     }
+    if (def->vsock) {
+        if (qemuAssignDeviceVsockAlias(def->vsock) < 0)
+            return -1;
+    }
 
     return 0;
 }
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index c7ff074e29..0b5ec4f2ba 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -9912,6 +9912,42 @@ qemuBuildSeccompSandboxCommandLine(virCommandPtr cmd,
 }
 
 
+static int
+qemuBuildVsockCommandLine(virCommandPtr cmd,
+                          virDomainDefPtr def,
+                          virDomainVsockDefPtr vsock,
+                          virQEMUCapsPtr qemuCaps)
+{
+    qemuDomainVsockPrivatePtr priv = (qemuDomainVsockPrivatePtr)vsock->privateData;
+    const char *device = "vhost-vsock-pci";
+    virBuffer buf = VIR_BUFFER_INITIALIZER;
+    char *devstr = NULL;
+    int ret = -1;
+
+    virBufferAsprintf(&buf, "%s", device);
+    virBufferAsprintf(&buf, ",id=%s", vsock->info.alias);
+    virBufferAsprintf(&buf, ",guest-cid=%u", vsock->guest_cid);
+    virBufferAsprintf(&buf, ",vhostfd=%u", priv->vhostfd);
+    if (qemuBuildDeviceAddressStr(&buf, def, &vsock->info, qemuCaps) < 0)
+        goto cleanup;
+
+    if (virBufferCheckError(&buf) < 0)
+        goto cleanup;
+
+    devstr = virBufferContentAndReset(&buf);
+
+    virCommandPassFD(cmd, priv->vhostfd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+    priv->vhostfd = -1;
+    virCommandAddArgList(cmd, "-device", devstr, NULL);
+
+    ret = 0;
+ cleanup:
+    virBufferFreeAndReset(&buf);
+    VIR_FREE(devstr);
+    return ret;
+}
+
+
 /*
  * Constructs a argv suitable for launching qemu with config defined
  * for a given virtual machine.
@@ -10161,6 +10197,10 @@ qemuBuildCommandLine(virQEMUDriverPtr driver,
             goto error;
     }
 
+    if (def->vsock &&
+        qemuBuildVsockCommandLine(cmd, def, def->vsock, qemuCaps) < 0)
+        goto error;
+
     /* In some situations, eg. VFIO passthrough, QEMU might need to lock a
      * significant amount of memory, so we need to set the limit accordingly */
     virCommandSetMaxMemLock(cmd, qemuDomainGetMemLockLimitBytes(def));
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 10f22b1cc2..2c51e4c0d8 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -1160,6 +1160,8 @@ qemuDomainVsockPrivateNew(void)
     if (!(priv = virObjectNew(qemuDomainVsockPrivateClass)))
         return NULL;
 
+    priv->vhostfd = -1;
+
     return (virObjectPtr) priv;
 }
 
@@ -1167,6 +1169,9 @@ qemuDomainVsockPrivateNew(void)
 static void
 qemuDomainVsockPrivateDispose(void *obj ATTRIBUTE_UNUSED)
 {
+    qemuDomainVsockPrivatePtr priv = obj;
+
+    VIR_FORCE_CLOSE(priv->vhostfd);
 }
 
 
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index f298ebf785..2e0f4df0fb 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -447,7 +447,7 @@ typedef qemuDomainVsockPrivate *qemuDomainVsockPrivatePtr;
 struct _qemuDomainVsockPrivate {
     virObject parent;
 
-    virTristateBool maybe;
+    int vhostfd;
 };
 
 
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 5f5759c9c8..30cc5904e0 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -79,6 +79,7 @@
 #include "nwfilter_conf.h"
 #include "netdev_bandwidth_conf.h"
 #include "virresctrl.h"
+#include "virvsock.h"
 
 #define VIR_FROM_THIS VIR_FROM_QEMU
 
@@ -5947,6 +5948,36 @@ qemuProcessPrepareHostStorage(virQEMUDriverPtr driver,
 }
 
 
+static int
+qemuProcessOpenVhostVsock(virDomainVsockDefPtr vsock)
+{
+    qemuDomainVsockPrivatePtr priv = (qemuDomainVsockPrivatePtr)vsock->privateData;
+    const char *vsock_path = "/dev/vhost-vsock";
+    int fd;
+
+    if ((fd = open(vsock_path, O_RDWR)) < 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       "%s", _("unable to open vhost-vsock device"));
+        return -1;
+    }
+
+    if (vsock->auto_cid == VIR_TRISTATE_BOOL_YES) {
+        if (virVsockAcquireGuestCid(fd, &vsock->guest_cid) < 0)
+            goto error;
+    } else {
+        if (virVsockSetGuestCid(fd, vsock->guest_cid) < 0)
+            goto error;
+    }
+
+    priv->vhostfd = fd;
+    return 0;
+
+ error:
+    VIR_FORCE_CLOSE(fd);
+    return -1;
+}
+
+
 /**
  * qemuProcessPrepareHost:
  * @driver: qemu driver
@@ -5972,6 +6003,10 @@ qemuProcessPrepareHost(virQEMUDriverPtr driver,
     if (qemuPrepareNVRAM(cfg, vm) < 0)
         goto cleanup;
 
+    if (vm->def->vsock) {
+        if (qemuProcessOpenVhostVsock(vm->def->vsock) < 0)
+            goto cleanup;
+    }
     /* network devices must be "prepared" before hostdevs, because
      * setting up a network device might create a new hostdev that
      * will need to be setup.
diff --git a/tests/qemuxml2argvdata/vhost-vsock-auto.x86_64-latest.args b/tests/qemuxml2argvdata/vhost-vsock-auto.x86_64-latest.args
new file mode 100644
index 0000000000..dd9b60ba3e
--- /dev/null
+++ b/tests/qemuxml2argvdata/vhost-vsock-auto.x86_64-latest.args
@@ -0,0 +1,32 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name guest=test,debug-threads=on \
+-S \
+-object secret,id=masterKey0,format=raw,\
+file=/tmp/lib/domain--1-test/master-key.aes \
+-machine pc-i440fx-2.9,accel=tcg,usb=off,dump-guest-core=off \
+-m 1024 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid bba65c0e-c049-934f-b6aa-4e2c0582acdf \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-test/monitor.sock,\
+server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot menu=on,strict=on \
+-device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \
+-device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
+resourcecontrol=deny \
+-device vhost-vsock-pci,id=vsock0,guest-cid=42,vhostfd=6789,bus=pci.0,addr=0x2 \
+-msg timestamp=on
diff --git a/tests/qemuxml2argvdata/vhost-vsock.x86_64-latest.args b/tests/qemuxml2argvdata/vhost-vsock.x86_64-latest.args
new file mode 100644
index 0000000000..907af8bb99
--- /dev/null
+++ b/tests/qemuxml2argvdata/vhost-vsock.x86_64-latest.args
@@ -0,0 +1,32 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name guest=test,debug-threads=on \
+-S \
+-object secret,id=masterKey0,format=raw,\
+file=/tmp/lib/domain--1-test/master-key.aes \
+-machine pc-0.13,accel=tcg,usb=off,dump-guest-core=off \
+-m 1024 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid bba65c0e-c049-934f-b6aa-4e2c0582acdf \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-test/monitor.sock,\
+server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot menu=on,strict=on \
+-device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \
+-device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
+resourcecontrol=deny \
+-device vhost-vsock-pci,id=vsock0,guest-cid=4,vhostfd=6789,bus=pci.0,addr=0x7 \
+-msg timestamp=on
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 2fe4390104..ddd2b88c0a 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -532,6 +532,17 @@ testCompareXMLToArgv(const void *data)
         }
     }
 
+    if (vm->def->vsock) {
+        virDomainVsockDefPtr vsock = vm->def->vsock;
+        qemuDomainVsockPrivatePtr vsockPriv =
+            (qemuDomainVsockPrivatePtr)vsock->privateData;
+
+        if (vsock->auto_cid == VIR_TRISTATE_BOOL_YES)
+            vsock->guest_cid = 42;
+
+        vsockPriv->vhostfd = 6789;
+    }
+
     if (!(cmd = qemuProcessCreatePretendCmd(&driver, vm, migrateURI,
                                             (flags & FLAG_FIPS), false,
                                             VIR_QEMU_PROCESS_START_COLD))) {
@@ -2856,6 +2867,9 @@ mymain(void)
             QEMU_CAPS_DEVICE_VIRTIO_MOUSE_CCW,
             QEMU_CAPS_DEVICE_VIRTIO_TABLET_CCW);
 
+    DO_TEST_CAPS_LATEST("vhost-vsock");
+    DO_TEST_CAPS_LATEST("vhost-vsock-auto");
+
     if (getenv("LIBVIRT_SKIP_CLEANUP") == NULL)
         virFileDeleteTree(fakerootdir);
 
-- 
2.16.1

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On Tue, May 29, 2018 at 14:53:14 +0200, Ján Tomko wrote:
> Create a new vsock endpoint by opening /dev/vhost-vsock,
> set the requested CID via ioctl (or assign a free one if auto='yes'),
> pass the file descriptor to QEMU and build the command line.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1291851
> Signed-off-by: Ján Tomko <jtomko@redhat.com>
> ---
> Rebased version with all the ACKed squash-ins for patches 1-6 available at:
> git://repo.or.cz/libvirt/jtomko.git vsock-v3
> http://repo.or.cz/libvirt/jtomko.git/shortlog/refs/heads/vsock-v3

Note that the linked branch is not in pushable state. Patch 3 does not
have a sign-off and the 'squash-in' patch was not actually squashed in.

In patch " util: create virvsock.c" there's a copy-paste error in the
docs for virVsockAcquireGuestCid, where it also mentions what
virVsockSetGuestCid does. Once you'll be editing that commit, please add
the colons after function names too.

ACK series with the two points above addressed.
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