Re: [PATCH v4 14/20] qemu: add vhost-user-gpu helper unit

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On 9/13/19 8:50 AM, marcandre.lureau@xxxxxxxxxx wrote:
From: Marc-André Lureau <marcandre.lureau@xxxxxxxxxx>

Similar to the qemu_tpm.c, add a unit with a few functions to
start/stop and setup the cgroup of the external vhost-user-gpu
process. See function documentation.

The vhost-user connection fd is set on qemuDomainVideoPrivate struct.

Signed-off-by: Marc-André Lureau <marcandre.lureau@xxxxxxxxxx>
---
  src/qemu/Makefile.inc.am       |   2 +
  src/qemu/qemu_domain.c         |   5 +-
  src/qemu/qemu_domain.h         |   2 +-
  src/qemu/qemu_vhost_user_gpu.c | 276 +++++++++++++++++++++++++++++++++
  src/qemu/qemu_vhost_user_gpu.h |  49 ++++++
  5 files changed, 332 insertions(+), 2 deletions(-)
  create mode 100644 src/qemu/qemu_vhost_user_gpu.c
  create mode 100644 src/qemu/qemu_vhost_user_gpu.h

diff --git a/src/qemu/Makefile.inc.am b/src/qemu/Makefile.inc.am
index 449550e64b..8040bf9366 100644
--- a/src/qemu/Makefile.inc.am
+++ b/src/qemu/Makefile.inc.am
@@ -66,6 +66,8 @@ QEMU_DRIVER_SOURCES = \
  	qemu/qemu_tpm.h \
  	qemu/qemu_vhost_user.c \
  	qemu/qemu_vhost_user.h \
+	qemu/qemu_vhost_user_gpu.c \
+	qemu/qemu_vhost_user_gpu.h \
  	$(NULL)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 9437694940..ab923aa917 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -1341,8 +1341,11 @@ qemuDomainVideoPrivateNew(void)
static void
-qemuDomainVideoPrivateDispose(void *obj ATTRIBUTE_UNUSED)
+qemuDomainVideoPrivateDispose(void *obj)
  {
+    qemuDomainVideoPrivatePtr priv = obj;
+
+    VIR_FORCE_CLOSE(priv->vhost_user_fd);
  }
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 89bd77b3c0..8afb4993d3 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -509,7 +509,7 @@ typedef qemuDomainVideoPrivate *qemuDomainVideoPrivatePtr;
  struct _qemuDomainVideoPrivate {
      virObject parent;
- bool tmp_to_remove;
+    int vhost_user_fd;
  };
diff --git a/src/qemu/qemu_vhost_user_gpu.c b/src/qemu/qemu_vhost_user_gpu.c
new file mode 100644
index 0000000000..b259b58434
--- /dev/null
+++ b/src/qemu/qemu_vhost_user_gpu.c
@@ -0,0 +1,276 @@
+/*
+ * qemu_vhost_user_gpu.c: QEMU vhost-user GPU support
+ *
+ * Copyright (C) 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include "qemu_vhost_user_gpu.h"
+#include "qemu_vhost_user.h"
+#include "qemu_extdevice.h"
+
+#include "conf/domain_conf.h"
+#include "configmake.h"
+#include "vircommand.h"
+#include "viralloc.h"
+#include "virlog.h"
+#include "virutil.h"
+#include "virfile.h"
+#include "virstring.h"
+#include "virtime.h"
+#include "virpidfile.h"
+
+#define VIR_FROM_THIS VIR_FROM_NONE
+
+VIR_LOG_INIT("qemu.vhost_user_gpu");
+
+
+static char *
+qemuVhostUserGPUCreatePidFilename(const char *stateDir,
+                                  const char *shortName,
+                                  const char *alias)
+{
+    VIR_AUTOFREE(char *) devicename = NULL;
+
+    if (virAsprintf(&devicename, "%s-%s-vhost-user-gpu", shortName, alias) < 0)
+        return NULL;
+
+    return virPidFileBuildPath(stateDir, devicename);
+}
+
+
+/*
+ * qemuVhostUserGPUGetPid:
+ * @binpath: path of executable associated with the pidfile
+ * @stateDir: the directory where vhost-user-gpu writes the pidfile into
+ * @shortName: short name of the domain
+ * @alias: video device alias
+ * @pid: pointer to pid
+ *
+ * Return -errno upon error, or zero on successful reading of the pidfile.
+ * If the PID was not still alive, zero will be returned, and @pid will be
+ * set to -1;
+ */
+static int
+qemuVhostUserGPUGetPid(const char *binPath,
+                       const char *stateDir,
+                       const char *shortName,
+                       const char *alias,
+                       pid_t *pid)
+{
+    VIR_AUTOFREE(char *) pidfile = NULL;
+
+    pidfile = qemuVhostUserGPUCreatePidFilename(stateDir, shortName, alias);
+    if (!pidfile)
+        return -ENOMEM;
+
+    return virPidFileReadPathIfAlive(pidfile, pid, binPath);
+}
+
+
+int qemuExtVhostUserGPUPrepareDomain(virQEMUDriverPtr driver,
+                                     virDomainVideoDefPtr video)
+{
+    return qemuVhostUserFillDomainGPU(driver, video);
+}
+
+
+/*
+ * qemuExtVhostUserGPUStart:
+ * @driver: QEMU driver
+ * @vm: the VM domain
+ * @video: the video device
+ *
+ * Start the external vhost-user-gpu process:
+ * - open a socketpair for vhost-user communication
+ * - have the command line built
+ * - start the external process and sync with it before QEMU start
+ */
+int qemuExtVhostUserGPUStart(virQEMUDriverPtr driver,
+                             virDomainObjPtr vm,
+                             virDomainVideoDefPtr video)
+{
+    VIR_AUTOUNREF(virQEMUDriverConfigPtr) cfg = virQEMUDriverGetConfig(driver);
+    VIR_AUTOFREE(char *) shortname = NULL;
+    VIR_AUTOFREE(char *) pidfile = NULL;
+    VIR_AUTOPTR(virCommand) cmd = NULL;
+    int pair[2] = { -1, -1 };
+    int cmdret = 0, rc;
+    int exitstatus = 0;
+    pid_t pid;
+    int ret = -1;
+
+    shortname = virDomainDefGetShortName(vm->def);
+    if (!shortname)
+        goto error;
+
+    /* stop any left-over for this VM */
+    qemuExtVhostUserGPUStop(driver, vm, video);
+
+    if (!(pidfile = qemuVhostUserGPUCreatePidFilename(
+              cfg->stateDir, shortname, video->info.alias)))
+        goto error;
+
+    if (qemuSecuritySetSocketLabel(driver->securityManager, vm->def) < 0)
+        goto error;
+
+    if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) < 0) {
+        virReportSystemError(errno, "%s", _("failed to create socket"));
+        goto error;
+    }
+
+    if (qemuSecurityClearSocketLabel(driver->securityManager, vm->def) < 0)
+        goto error;
+
+    cmd = virCommandNew(video->driver->vhost_user_binary);
+    if (!cmd)
+        goto error;
+
+    virCommandClearCaps(cmd);
+    virCommandSetPidFile(cmd, pidfile);
+    virCommandDaemonize(cmd);
+
+    if (qemuExtDeviceLogCommand(driver, vm, cmd, "vhost-user-gpu") < 0)
+        goto error;
+

Most, possibly all, of these 'goto error;' usages are overwriting detailed error messages with 'vhost-user-gpu failed to start'. So this needs to be reworked. You can use virGetLastErrorMessage if you wanted to prepend the vhost-user specific bit to the error. Maybe break up this function into chunks, like one to build the Command object

+    virCommandAddArgFormat(cmd, "--fd=%d", pair[0]);
+    virCommandPassFD(cmd, pair[0], VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+    pair[0] = -1;
+
+    if (video->accel) {
+        if (video->accel->accel3d)
+            virCommandAddArg(cmd, "--virgl");
+
+        if (video->accel->rendernode)
+            virCommandAddArgFormat(cmd, "--render-node=%s", video->accel->rendernode);
+    }
+
+    if (qemuSecurityStartVhostUserGPU(driver, vm, cmd,
+                                      &exitstatus, &cmdret) < 0)
+        goto error;
+
+    if (cmdret < 0 || exitstatus != 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Could not start 'vhost-user-gpu'. exitstatus: %d"), exitstatus);
+        goto cleanup;
+    }
+

cmdret < 0 will trigger StartVhostUserGPU to return -1, so we will never hit one condition of the below case

Otherwise this looks good. Since the series is pretty close otherwise, these bits can be addressed in a follow up patch IMO

Reviewed-by: Cole Robinson <crobinso@xxxxxxxxxx>

- Cole

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