qemu: add vhost-user-gpu helper unit

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: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NCole Robinson <crobinso@redhat.com>

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)
 
 

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);
 }
 
 

src/qemu/qemu_domain.h

@@ -509,7 +509,7 @@ typedef qemuDomainVideoPrivate *qemuDomainVideoPrivatePtr;
 struct _qemuDomainVideoPrivate {
     virObject parent;
 
-    bool tmp_to_remove;
+    int vhost_user_fd;
 };
 
 

src/qemu/qemu_vhost_user_gpu.c

+/*
+ * 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;
+
+    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;
+    }
+
+    rc = virPidFileReadPath(pidfile, &pid);
+    if (rc < 0) {
+        virReportSystemError(-rc,
+                             _("Unable to read vhost-user-gpu pidfile '%s'"),
+                             pidfile);
+        goto cleanup;
+    }
+
+    ret = 0;
+    QEMU_DOMAIN_VIDEO_PRIVATE(video)->vhost_user_fd = pair[1];
+    pair[1] = -1;
+
+ cleanup:
+    VIR_FORCE_CLOSE(pair[0]);
+    VIR_FORCE_CLOSE(pair[1]);
+
+    return ret;
+
+ error:
+    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                   _("vhost-user-gpu failed to start"));
+    goto cleanup;
+}
+
+
+/*
+ * qemuExtVhostUserGPUStop:
+ *
+ * @driver: QEMU driver
+ * @vm: the VM domain
+ * @video: the video device
+ *
+ * Check if vhost-user process pidfile is around, kill the process,
+ * and remove the pidfile.
+ */
+void qemuExtVhostUserGPUStop(virQEMUDriverPtr driver,
+                             virDomainObjPtr vm,
+                             virDomainVideoDefPtr video)
+{
+    VIR_AUTOUNREF(virQEMUDriverConfigPtr) cfg = virQEMUDriverGetConfig(driver);
+    VIR_AUTOFREE(char *) pidfile = NULL;
+    VIR_AUTOFREE(char *) shortname = NULL;
+    virErrorPtr orig_err;
+
+    shortname = virDomainDefGetShortName(vm->def);
+    if (!(pidfile = qemuVhostUserGPUCreatePidFilename(
+              cfg->stateDir, shortname, video->info.alias))) {
+        VIR_WARN("Unable to construct vhost-user-gpu pidfile path");
+        return;
+    }
+
+    virErrorPreserveLast(&orig_err);
+    if (virPidFileForceCleanupPath(pidfile) < 0) {
+        VIR_WARN("Unable to kill vhost-user-gpu process");
+    } else {
+        if (unlink(pidfile) < 0 &&
+            errno != ENOENT) {
+            virReportSystemError(errno,
+                                 _("Unable to remove stale pidfile %s"),
+                                 pidfile);
+        }
+    }
+    virErrorRestore(&orig_err);
+}
+
+
+/*
+ * qemuExtVhostUserGPUSetupCgroup:
+ *
+ * @driver: QEMU driver
+ * @def: domain definition
+ * @video: the video device
+ * @cgroupe: a cgroup
+ *
+ * Add the vhost-user-gpu PID to the given cgroup.
+ */
+int
+qemuExtVhostUserGPUSetupCgroup(virQEMUDriverPtr driver,
+                               virDomainDefPtr def,
+                               virDomainVideoDefPtr video,
+                               virCgroupPtr cgroup)
+{
+    VIR_AUTOUNREF(virQEMUDriverConfigPtr) cfg = virQEMUDriverGetConfig(driver);
+    VIR_AUTOFREE(char *) shortname = NULL;
+    int rc;
+    pid_t pid;
+
+    shortname = virDomainDefGetShortName(def);
+    if (!shortname)
+        return -1;
+
+    rc = qemuVhostUserGPUGetPid(video->driver->vhost_user_binary,
+                                cfg->stateDir, shortname, video->info.alias, &pid);
+    if (rc < 0 || (rc == 0 && pid == (pid_t)-1)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("Could not get process id of vhost-user-gpu"));
+        return -1;
+    }
+    if (virCgroupAddProcess(cgroup, pid) < 0)
+        return -1;
+
+    return 0;
+}

src/qemu/qemu_vhost_user_gpu.h

+/*
+ * qemu_vhost_user_gpu.h: 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/>.
+ */
+
+#pragma once
+
+#include "domain_conf.h"
+#include "qemu_domain.h"
+#include "qemu_security.h"
+
+int qemuExtVhostUserGPUPrepareDomain(virQEMUDriverPtr driver,
+                                     virDomainVideoDefPtr video)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
+    ATTRIBUTE_RETURN_CHECK;
+
+int qemuExtVhostUserGPUStart(virQEMUDriverPtr driver,
+                             virDomainObjPtr vm,
+                             virDomainVideoDefPtr video)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
+    ATTRIBUTE_RETURN_CHECK;
+
+void qemuExtVhostUserGPUStop(virQEMUDriverPtr driver,
+                             virDomainObjPtr def,
+                             virDomainVideoDefPtr video)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+
+int
+qemuExtVhostUserGPUSetupCgroup(virQEMUDriverPtr driver,
+                               virDomainDefPtr def,
+                               virDomainVideoDefPtr video,
+                               virCgroupPtr cgroup)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
+    ATTRIBUTE_RETURN_CHECK;