[libvirt] [RFC v2 10/16] qemu: add vhost-user-gpu helper unit
Ján Tomko
jtomko at redhat.com
Fri Oct 5 14:11:16 UTC 2018
On Tue, Aug 28, 2018 at 11:39:28PM +0200, marcandre.lureau at redhat.com wrote:
>From: Marc-André Lureau <marcandre.lureau at 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.
>
>Signed-off-by: Marc-André Lureau <marcandre.lureau at redhat.com>
>---
> src/conf/device_conf.h | 1 +
> src/qemu/Makefile.inc.am | 2 +
> src/qemu/qemu_vhost_user_gpu.c | 318 +++++++++++++++++++++++++++++++++
> src/qemu/qemu_vhost_user_gpu.h | 48 +++++
> 4 files changed, 369 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 ff7d6c9d5f..79a7ea9fe2 100644
>--- a/src/conf/device_conf.h
>+++ b/src/conf/device_conf.h
>@@ -175,6 +175,7 @@ struct _virDomainDeviceInfo {
> * cases we might want to prevent that from happening by
> * locking the isolation group */
> bool isolationGroupLocked;
>+ int vhost_user_fd;
> };
>
> int virDomainDeviceInfoCopy(virDomainDeviceInfoPtr dst,
>diff --git a/src/qemu/Makefile.inc.am b/src/qemu/Makefile.inc.am
>index 2afa67f195..28daf9d426 100644
>--- a/src/qemu/Makefile.inc.am
>+++ b/src/qemu/Makefile.inc.am
>@@ -56,6 +56,8 @@ QEMU_DRIVER_SOURCES = \
> qemu/qemu_qapi.h \
> qemu/qemu_tpm.c \
> qemu/qemu_tpm.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..9007614020
>--- /dev/null
>+++ b/src/qemu/qemu_vhost_user_gpu.c
>@@ -0,0 +1,318 @@
>+/*
>+ * 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/>.
>+ *
>+ * Author: Marc-André Lureau <marcandre.lureau at redhat.com>
>+ */
>+
>+#include <config.h>
>+
>+#include "qemu_extdevice.h"
>+#include "qemu_domain.h"
>+#include "qemu_security.h"
>+
>+#include "conf/domain_conf.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"
>+#include "qemu_vhost_user_gpu.h"
>+
>+#define VIR_FROM_THIS VIR_FROM_NONE
>+
>+VIR_LOG_INIT("qemu.vhost-user-gpu")
>+
>+/*
>+ * Look up the vhost-user-gpu executable; to be found on the host
>+ */
>+static char *vhost_user_gpu_path;
>+
>+static int
>+qemuVhostUserGPUInit(void)
>+{
>+ if (!vhost_user_gpu_path) {
>+ vhost_user_gpu_path = virFindFileInPath("vhost-user-gpu");
>+ if (!vhost_user_gpu_path) {
>+ virReportSystemError(ENOENT, "%s",
>+ _("Unable to find 'vhost-user-gpu' binary in $PATH"));
>+ return -1;
>+ }
>+ if (!virFileIsExecutable(vhost_user_gpu_path)) {
>+ virReportError(VIR_ERR_INTERNAL_ERROR,
>+ _("vhost-user-gpu %s is not an executable"),
>+ vhost_user_gpu_path);
>+ VIR_FREE(vhost_user_gpu_path);
>+ return -1;
>+ }
>+ }
>+
>+ return 0;
>+}
>+
>+
>+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
>+ *
>+ * @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 *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, vhost_user_gpu_path);
>+
>+ VIR_FREE(pidfile);
>+
>+ return ret;
>+}
>+
>+
>+/*
>+ * qemuExtVhostUserGPUStart:
>+ *
>+ * @driver: QEMU driver
>+ * @def: domain definition
>+ * @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,
>+ virDomainDefPtr def,
>+ virDomainVideoDefPtr video,
>+ qemuDomainLogContextPtr logCtxt)
>+{
>+ int ret = -1;
>+ virCommandPtr cmd = NULL;
>+ int exitstatus = 0;
>+ char *errbuf = NULL;
>+ virQEMUDriverConfigPtr cfg;
>+ char *pidfile, *shortName = virDomainDefGetShortName(def);
>+ virTimeBackOffVar timebackoff;
>+ const unsigned long long timeout = 500000; /* ms */
500 * 1000 /* ms */ is easier to read
>+ 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, def, video);
>+
>+ if (!(pidfile = qemuVhostUserGPUCreatePidFilename(
>+ cfg->stateDir, shortName, video->info.alias)))
>+ goto error;
>+
>+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) < 0) {
>+ virReportSystemError(errno, "%s", _("failed to create socket"));
>+ goto error;
>+ }
This socket will inherit the label from libvirtd and it cannot be changed
afterwards, see:
https://bugzilla.redhat.com/show_bug.cgi?id=999926
We have SecuritySetSocketLabel and SecurityClearSocketLabel that change
the context temporarily.
Having them on-disk would let us change the label afterwards, but for
FD passing, they should be labeled before the fork (unlike all the other
paths which we label after forking)
Jano
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