This commit share host Real Time Clock device (rtc) into LXC containers
to support hardware clock. This should be available setting up a `rtc`
timer under clock section. Since this option is not emulated, it should
be available only for `localtime` clock. This option should be readonly
due to security reasons.
Before:
root# hwclock --verbose
hwclock from util-linux 2.32.1
System Time: 1581877557.598365
Trying to open: /dev/rtc0
Trying to open: /dev/rtc
Trying to open: /dev/misc/rtc
No usable clock interface found.
hwclock: Cannot access the Hardware Clock via any known method.
Now:
root# hwclock
2020-02-16 18:23:55.374134+00:00
root# hwclock -w
hwclock: ioctl(RTC_SET_TIME) to /dev/rtc to set the time failed:
Permission denied
Signed-off-by: Julio Faracco <jcfaracco@xxxxxxxxx>
---
docs/formatdomain.html.in | 2 +-
src/lxc/lxc_cgroup.c | 33 ++++++++++++++++++++
src/lxc/lxc_controller.c | 66 +++++++++++++++++++++++++++++++++++++++
3 files changed, 100 insertions(+), 1 deletion(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 28770188dd..96d06e9c3e 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -2465,7 +2465,7 @@
being modified, and can be one of
"platform" (currently unsupported),
"hpet" (libxl, xen, qemu), "kvmclock" (qemu),
- "pit" (qemu), "rtc" (qemu), "tsc" (libxl, qemu -
+ "pit" (qemu), "rtc" (qemu, lxc), "tsc" (libxl, qemu -
<span class="since">since 3.2.0</span>), "hypervclock"
(qemu - <span class="since">since 1.2.2</span>) or
"armvtimer" (qemu - <span class="since">since 6.1.0</span>).
diff --git a/src/lxc/lxc_cgroup.c b/src/lxc/lxc_cgroup.c
index 952d021418..065996b3a4 100644
--- a/src/lxc/lxc_cgroup.c
+++ b/src/lxc/lxc_cgroup.c
@@ -333,6 +333,39 @@ static int virLXCCgroupSetupDeviceACL(virDomainDefPtr def,
VIR_CGROUP_DEVICE_RWM) < 0)
return -1;
+ VIR_DEBUG("Allowing timers char devices");
+
+ /* Sync'ed with Host clock */
+ for (i = 0; i < def->clock.ntimers; i++) {
+ virDomainTimerDefPtr timer = def->clock.timers[i];
+
+ /* Check if "present" is set to "no" otherwise enable it. */
+ if (!timer->present)
+ continue;
+
+ switch ((virDomainTimerNameType)timer->name) {
+ case VIR_DOMAIN_TIMER_NAME_PLATFORM:
+ case VIR_DOMAIN_TIMER_NAME_TSC:
+ case VIR_DOMAIN_TIMER_NAME_KVMCLOCK:
+ case VIR_DOMAIN_TIMER_NAME_HYPERVCLOCK:
+ case VIR_DOMAIN_TIMER_NAME_PIT:
+ case VIR_DOMAIN_TIMER_NAME_HPET:
+ case VIR_DOMAIN_TIMER_NAME_ARMVTIMER:
+ case VIR_DOMAIN_TIMER_NAME_LAST:
+ break;
+ case VIR_DOMAIN_TIMER_NAME_RTC:
+ if (virFileExists("/dev/rtc")) {
+ if (virCgroupAllowDevicePath(cgroup, "/dev/rtc",
+ VIR_CGROUP_DEVICE_READ,
+ false) < 0)
+ return -1;
+ } else {
+ VIR_DEBUG("Ignoring non-existent device /dev/rtc");
+ }
+ break;
+ }
+ }
+
VIR_DEBUG("Device whitelist complete");
return 0;
diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
index fa7b9dd0e7..d97c4ad1b5 100644
--- a/src/lxc/lxc_controller.c
+++ b/src/lxc/lxc_controller.c
@@ -1530,6 +1530,69 @@ static int virLXCControllerPopulateDevices(virLXCControllerPtr ctrl)
}
+static int
+virLXCControllerSetupTimers(virLXCControllerPtr ctrl)
+{
+ g_autofree char *path = NULL;
+ size_t i;
+ struct stat sb;
+ virDomainDefPtr def = ctrl->def;
+ const char *rtc_dev = "/dev/rtc";
+
+ /* Not sync'ed with Host clock */
+ if (def->clock.offset != VIR_DOMAIN_CLOCK_OFFSET_LOCALTIME)
+ return 0;
+
+ for (i = 0; i < def->clock.ntimers; i++) {
+ dev_t dev;
+ virDomainTimerDefPtr timer = def->clock.timers[i];
+
+ /* Check if "present" is set to "no" otherwise enable it. */
+ if (!timer->present)
+ continue;
+
+ switch ((virDomainTimerNameType)timer->name) {
+ case VIR_DOMAIN_TIMER_NAME_PLATFORM:
+ case VIR_DOMAIN_TIMER_NAME_TSC:
+ case VIR_DOMAIN_TIMER_NAME_KVMCLOCK:
+ case VIR_DOMAIN_TIMER_NAME_HYPERVCLOCK:
+ case VIR_DOMAIN_TIMER_NAME_PIT:
+ case VIR_DOMAIN_TIMER_NAME_HPET:
+ case VIR_DOMAIN_TIMER_NAME_ARMVTIMER:
+ case VIR_DOMAIN_TIMER_NAME_LAST:
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("unsupported timer type (name) '%s'"),
+ virDomainTimerNameTypeToString(timer->name));
+ return -1;
+ case VIR_DOMAIN_TIMER_NAME_RTC:
+ if (stat(rtc_dev, &sb) < 0) {
+ virReportSystemError(errno, _("Unable to access %s"),
+ rtc_dev);
+ return -1;
+ }
+
+ path = g_strdup_printf("/%s/%s.dev/%s", LXC_STATE_DIR,
+ ctrl->def->name, "/rtc");
+
+ dev = makedev(major(sb.st_rdev), minor(sb.st_rdev));
+ if (mknod(path, S_IFCHR, dev) < 0 ||
+ chmod(path, sb.st_mode)) {
+ virReportSystemError(errno,
+ _("Failed to make device %s"),
+ path);
+ return -1;
+ }
+
+ if (lxcContainerChown(ctrl->def, path) < 0)
+ return -1;
+ break;
+ }
+ }
+
+ return 0;
+}
+
+
static int
virLXCControllerSetupHostdevSubsysUSB(virDomainDefPtr vmDef,
virDomainHostdevDefPtr def,
@@ -2321,6 +2384,9 @@ virLXCControllerRun(virLXCControllerPtr ctrl)
if (virLXCControllerPopulateDevices(ctrl) < 0)
goto cleanup;
+ if (virLXCControllerSetupTimers(ctrl) < 0)
+ goto cleanup;
+
if (virLXCControllerSetupAllDisks(ctrl) < 0)
goto cleanup;
--
2.24.1
