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[libvirt] [PATCH v2 11/16] qemu: add vhost-user-gpu helper unit



From: Marc-André Lureau <marcandre lureau redhat com>

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.

Since the vhost-user connection fd isn't necessarily specific to QEMU,
it was easier to add it to virDomainDeviceInfo, although a reasonable
place could be qemuDomainObjPrivate (with an associate hashtable
device-info -> qemu-device-info for example).

Signed-off-by: Marc-André Lureau <marcandre lureau redhat com>
Signed-off-by: Cole Robinson <crobinso redhat com>
---
 src/conf/device_conf.h         |   1 +
 src/qemu/Makefile.inc.am       |   2 +
 src/qemu/qemu_vhost_user_gpu.c | 305 +++++++++++++++++++++++++++++++++
 src/qemu/qemu_vhost_user_gpu.h |  50 ++++++
 4 files changed, 358 insertions(+)
 create mode 100644 src/qemu/qemu_vhost_user_gpu.c
 create mode 100644 src/qemu/qemu_vhost_user_gpu.h

diff --git a/src/conf/device_conf.h b/src/conf/device_conf.h
index 0b0c525ad8..23cc2e9ba6 100644
--- a/src/conf/device_conf.h
+++ b/src/conf/device_conf.h
@@ -180,6 +180,7 @@ struct _virDomainDeviceInfo {
      * locking the isolation group */
     bool isolationGroupLocked;
     char *vhost_user_binary;
+    int vhost_user_fd;
 };
 
 void virDomainDeviceInfoClear(virDomainDeviceInfoPtr info);
diff --git a/src/qemu/Makefile.inc.am b/src/qemu/Makefile.inc.am
index 18a9220d01..d394eab957 100644
--- a/src/qemu/Makefile.inc.am
+++ b/src/qemu/Makefile.inc.am
@@ -62,6 +62,8 @@ 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_vhost_user_gpu.c b/src/qemu/qemu_vhost_user_gpu.c
new file mode 100644
index 0000000000..0735af1473
--- /dev/null
+++ b/src/qemu/qemu_vhost_user_gpu.c
@@ -0,0 +1,305 @@
+/*
+ * qemu_vhost_user_gpu.c: QEMU vhost-user GPU support
+ *
+ * Copyright (C) 2018 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)
+{
+    char *pidfile = NULL;
+    char *devicename = NULL;
+
+    if (virAsprintf(&devicename, "%s-%s-vhost-user-gpu", shortName, alias) < 0)
+        return NULL;
+
+    pidfile = virPidFileBuildPath(stateDir, devicename);
+
+    VIR_FREE(devicename);
+
+    return pidfile;
+}
+
+
+/*
+ * 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)
+{
+    int ret;
+    char *pidfile = qemuVhostUserGPUCreatePidFilename(stateDir, shortName, alias);
+    if (!pidfile)
+        return -ENOMEM;
+
+    ret = virPidFileReadPathIfAlive(pidfile, pid, binPath);
+
+    VIR_FREE(pidfile);
+
+    return ret;
+}
+
+
+int qemuExtVhostUserGPUPrepareDomain(virQEMUDriverPtr driver,
+                                     virDomainVideoDefPtr video)
+{
+    return qemuVhostUserFillDomainGPU(driver, video);
+}
+
+
+/*
+ * qemuExtVhostUserGPUStart:
+ * @driver: QEMU driver
+ * @vm: the VM domain
+ * @video: the video device
+ * @logCtxt: log context
+ *
+ * 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,
+                             qemuDomainLogContextPtr logCtxt)
+{
+    int ret = -1;
+    virCommandPtr cmd = NULL;
+    int exitstatus = 0;
+    char *errbuf = NULL;
+    virQEMUDriverConfigPtr cfg;
+    char *pidfile = NULL, *shortName = virDomainDefGetShortName(vm->def);
+    virTimeBackOffVar timebackoff;
+    const unsigned long long timeout = 500 * 1000; /* ms */
+    int cmdret = 0, rc;
+    int pair[2] = { -1, -1 };
+
+    pid_t pid;
+
+    if (!shortName)
+        return -1;
+
+    cfg = virQEMUDriverGetConfig(driver);
+
+    /* 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 cleanup;
+
+    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 cleanup;
+
+    cmd = virCommandNew(video->info.vhost_user_binary);
+    if (!cmd)
+        goto error;
+
+    virCommandClearCaps(cmd);
+    virCommandSetPidFile(cmd, pidfile);
+    virCommandDaemonize(cmd);
+
+    if (qemuExtDeviceLogCommand(logCtxt, 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, "
+                         "error: %s"), exitstatus, errbuf);
+        goto cleanup;
+    }
+
+    /* check that the helper has written its pid into the file */
+    if (virTimeBackOffStart(&timebackoff, 1, timeout) < 0)
+        goto error;
+    while (virTimeBackOffWait(&timebackoff)) {
+        rc = qemuVhostUserGPUGetPid(video->info.vhost_user_binary,
+                                    cfg->stateDir, shortName, video->info.alias, &pid);
+        if (rc < 0)
+            continue;
+        if (rc == 0 && pid == (pid_t)-1)
+            goto error;
+        break;
+    }
+
+    ret = 0;
+    video->info.vhost_user_fd = pair[1];
+    pair[1] = -1;
+
+ cleanup:
+    VIR_FORCE_CLOSE(pair[0]);
+    VIR_FORCE_CLOSE(pair[1]);
+    virObjectUnref(cfg);
+    VIR_FREE(pidfile);
+    virCommandFree(cmd);
+
+    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)
+{
+    virErrorPtr orig_err;
+    char *pidfile, *shortName = virDomainDefGetShortName(vm->def);
+    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+
+    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);
+
+    VIR_FREE(pidfile);
+}
+
+
+/*
+ * 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)
+{
+    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    char *pidfile = NULL;
+    char *shortName = NULL;
+    int ret = -1, rc;
+    pid_t pid;
+
+    shortName = virDomainDefGetShortName(def);
+    if (!shortName)
+        goto cleanup;
+
+    rc = qemuVhostUserGPUGetPid(video->info.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"));
+        goto cleanup;
+    }
+    if (virCgroupAddProcess(cgroup, pid) < 0)
+        goto cleanup;
+
+    ret = 0;
+
+ cleanup:
+    VIR_FREE(pidfile);
+    VIR_FREE(shortName);
+    virObjectUnref(cfg);
+
+    return ret;
+}
diff --git a/src/qemu/qemu_vhost_user_gpu.h b/src/qemu/qemu_vhost_user_gpu.h
new file mode 100644
index 0000000000..85054894fd
--- /dev/null
+++ b/src/qemu/qemu_vhost_user_gpu.h
@@ -0,0 +1,50 @@
+/*
+ * qemu_vhost_user_gpu.h: QEMU vhost-user GPU support
+ *
+ * Copyright (C) 2018 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,
+                             qemuDomainLogContextPtr logCtxt)
+    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;
-- 
2.21.0


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