There are two modes of core scheduling that are handy wrt virCommand: 1) create new trusted group when executing a virCommand 2) place freshly executed virCommand into the trusted group of another process. Therefore, implement these two new operations as new APIs: virCommandSetRunAlone() and virCommandSetRunAmong(), respectively. Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> Reviewed-by: Daniel P. Berrangé <berrange@xxxxxxxxxx> --- src/libvirt_private.syms | 2 ++ src/util/vircommand.c | 63 ++++++++++++++++++++++++++++++++++++++++ src/util/vircommand.h | 5 ++++ 3 files changed, 70 insertions(+) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 23abf663f6..02d1c753a4 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -2103,6 +2103,8 @@ virCommandSetOutputBuffer; virCommandSetOutputFD; virCommandSetPidFile; virCommandSetPreExecHook; +virCommandSetRunAlone; +virCommandSetRunAmong; virCommandSetSELinuxLabel; virCommandSetSendBuffer; virCommandSetUID; diff --git a/src/util/vircommand.c b/src/util/vircommand.c index d78c666f28..745e7c560c 100644 --- a/src/util/vircommand.c +++ b/src/util/vircommand.c @@ -148,6 +148,13 @@ struct _virCommand { #endif int mask; + /* schedCore values: + * 0: no core scheduling + * >0: copy scheduling group from PID + * -1: create new scheduling group + */ + pid_t schedCore; + virCommandSendBuffer *sendBuffers; size_t numSendBuffers; }; @@ -434,6 +441,22 @@ virCommandHandshakeChild(virCommand *cmd) static int virExecCommon(virCommand *cmd, gid_t *groups, int ngroups) { + /* Do this before dropping capabilities. */ + if (cmd->schedCore == -1 && + virProcessSchedCoreCreate() < 0) { + virReportSystemError(errno, "%s", + _("Unable to set SCHED_CORE")); + return -1; + } + + if (cmd->schedCore > 0 && + virProcessSchedCoreShareFrom(cmd->schedCore) < 0) { + virReportSystemError(errno, + _("Unable to run among %llu"), + (unsigned long long) cmd->schedCore); + return -1; + } + if (cmd->uid != (uid_t)-1 || cmd->gid != (gid_t)-1 || cmd->capabilities || (cmd->flags & VIR_EXEC_CLEAR_CAPS)) { VIR_DEBUG("Setting child uid:gid to %d:%d with caps %llx", @@ -3386,3 +3409,43 @@ virCommandRunNul(virCommand *cmd G_GNUC_UNUSED, return -1; } #endif /* WIN32 */ + +/** + * virCommandSetRunAlone: + * + * Create new trusted group when running the command. In other words, the + * process won't be scheduled to run on a core among with processes from + * another, untrusted group. + */ +void +virCommandSetRunAlone(virCommand *cmd) +{ + if (virCommandHasError(cmd)) + return; + + cmd->schedCore = -1; +} + +/** + * virCommandSetRunAmong: + * @pid: pid from a trusted group + * + * When spawning the command place it into the trusted group of @pid so that + * these two processes can run on Hyper Threads of a single core at the same + * time. + */ +void +virCommandSetRunAmong(virCommand *cmd, + pid_t pid) +{ + if (virCommandHasError(cmd)) + return; + + if (pid <= 0) { + VIR_DEBUG("invalid pid value: %lld", (long long) pid); + cmd->has_error = -1; + return; + } + + cmd->schedCore = pid; +} diff --git a/src/util/vircommand.h b/src/util/vircommand.h index c7a580e152..98788bcbf7 100644 --- a/src/util/vircommand.h +++ b/src/util/vircommand.h @@ -217,4 +217,9 @@ int virCommandRunNul(virCommand *cmd, virCommandRunNulFunc func, void *data); +void virCommandSetRunAlone(virCommand *cmd); + +void virCommandSetRunAmong(virCommand *cmd, + pid_t pid); + G_DEFINE_AUTOPTR_CLEANUP_FUNC(virCommand, virCommandFree); -- 2.35.1