diff options
| -rw-r--r-- | src/cpu/kvm/base.cc | 80 | ||||
| -rw-r--r-- | src/cpu/kvm/base.hh | 22 |
2 files changed, 42 insertions, 60 deletions
diff --git a/src/cpu/kvm/base.cc b/src/cpu/kvm/base.cc index 1149a3704..8ba9f944e 100644 --- a/src/cpu/kvm/base.cc +++ b/src/cpu/kvm/base.cc @@ -63,8 +63,6 @@ /* Used by some KVM macros */ #define PAGE_SIZE pageSize -static volatile __thread bool timerOverflowed = false; - BaseKvmCPU::BaseKvmCPU(BaseKvmCPUParams *params) : BaseCPU(params), vm(*params->kvmVM), @@ -178,6 +176,8 @@ BaseKvmCPU::startupThread() const BaseKvmCPUParams * const p( dynamic_cast<const BaseKvmCPUParams *>(params())); + vcpuThread = pthread_self(); + // Setup signal handlers. This has to be done after the vCPU is // created since it manipulates the vCPU signal mask. setupSignalHandler(); @@ -186,11 +186,11 @@ BaseKvmCPU::startupThread() if (p->usePerfOverflow) runTimer.reset(new PerfKvmTimer(hwCycles, - KVM_TIMER_SIGNAL, + KVM_KICK_SIGNAL, p->hostFactor, p->hostFreq)); else - runTimer.reset(new PosixKvmTimer(KVM_TIMER_SIGNAL, CLOCK_MONOTONIC, + runTimer.reset(new PosixKvmTimer(KVM_KICK_SIGNAL, CLOCK_MONOTONIC, p->hostFactor, p->hostFreq)); @@ -607,7 +607,6 @@ BaseKvmCPU::kvmRun(Tick ticks) { Tick ticksExecuted; DPRINTF(KvmRun, "KVM: Executing for %i ticks\n", ticks); - timerOverflowed = false; if (ticks == 0) { // Settings ticks == 0 is a special case which causes an entry @@ -617,16 +616,18 @@ BaseKvmCPU::kvmRun(Tick ticks) ++numVMHalfEntries; - // This signal is always masked while we are executing in gem5 - // and gets unmasked temporarily as soon as we enter into + // Send a KVM_KICK_SIGNAL to the vCPU thread (i.e., this + // thread). The KVM control signal is masked while executing + // in gem5 and gets unmasked temporarily as when entering // KVM. See setSignalMask() and setupSignalHandler(). - raise(KVM_TIMER_SIGNAL); + kick(); - // Enter into KVM. KVM will check for signals after completing - // pending operations (IO). Since the KVM_TIMER_SIGNAL is - // pending, this forces an immediate exit into gem5 again. We + // Start the vCPU. KVM will check for signals after completing + // pending operations (IO). Since the KVM_KICK_SIGNAL is + // pending, this forces an immediate exit to gem5 again. We // don't bother to setup timers since this shouldn't actually - // execute any code in the guest. + // execute any code (other than completing half-executed IO + // instructions) in the guest. ioctlRun(); // We always execute at least one cycle to prevent the @@ -659,27 +660,18 @@ BaseKvmCPU::kvmRun(Tick ticks) if (!perfControlledByTimer) hwCycles.stop(); - // The timer signal may have been delivered after we exited + // The control signal may have been delivered after we exited // from KVM. It will be pending in that case since it is // masked when we aren't executing in KVM. Discard it to make // sure we don't deliver it immediately next time we try to // enter into KVM. - discardPendingSignal(KVM_TIMER_SIGNAL); - discardPendingSignal(KVM_INST_SIGNAL); + discardPendingSignal(KVM_KICK_SIGNAL); const uint64_t hostCyclesExecuted(getHostCycles() - baseCycles); const uint64_t simCyclesExecuted(hostCyclesExecuted * hostFactor); const uint64_t instsExecuted(hwInstructions.read() - baseInstrs); ticksExecuted = runTimer->ticksFromHostCycles(hostCyclesExecuted); - if (ticksExecuted < ticks && - timerOverflowed && - _kvmRun->exit_reason == KVM_EXIT_INTR) { - // TODO: We should probably do something clever here... - warn("KVM: Early timer event, requested %i ticks but got %i ticks.\n", - ticks, ticksExecuted); - } - /* Update statistics */ numCycles += simCyclesExecuted;; numInsts += instsExecuted; @@ -1065,10 +1057,9 @@ BaseKvmCPU::flushCoalescedMMIO() } /** - * Cycle timer overflow when running in KVM. Forces the KVM syscall to - * exit with EINTR and allows us to run the event queue. + * Dummy handler for KVM kick signals. * - * @warn This function might not be called since some kernels don't + * @note This function is usually not called since the kernel doesn't * seem to deliver signals when the signal is only unmasked when * running in KVM. This doesn't matter though since we are only * interested in getting KVM to exit, which happens as expected. See @@ -1076,18 +1067,7 @@ BaseKvmCPU::flushCoalescedMMIO() * handling. */ static void -onTimerOverflow(int signo, siginfo_t *si, void *data) -{ - timerOverflowed = true; -} - -/** - * Instruction counter overflow when running in KVM. Forces the KVM - * syscall to exit with EINTR and allows us to handle instruction - * count events. - */ -static void -onInstEvent(int signo, siginfo_t *si, void *data) +onKickSignal(int signo, siginfo_t *si, void *data) { } @@ -1097,33 +1077,25 @@ BaseKvmCPU::setupSignalHandler() struct sigaction sa; memset(&sa, 0, sizeof(sa)); - sa.sa_sigaction = onTimerOverflow; + sa.sa_sigaction = onKickSignal; sa.sa_flags = SA_SIGINFO | SA_RESTART; - if (sigaction(KVM_TIMER_SIGNAL, &sa, NULL) == -1) + if (sigaction(KVM_KICK_SIGNAL, &sa, NULL) == -1) panic("KVM: Failed to setup vCPU timer signal handler\n"); - memset(&sa, 0, sizeof(sa)); - sa.sa_sigaction = onInstEvent; - sa.sa_flags = SA_SIGINFO | SA_RESTART; - if (sigaction(KVM_INST_SIGNAL, &sa, NULL) == -1) - panic("KVM: Failed to setup vCPU instruction signal handler\n"); - sigset_t sigset; if (pthread_sigmask(SIG_BLOCK, NULL, &sigset) == -1) panic("KVM: Failed get signal mask\n"); // Request KVM to setup the same signal mask as we're currently - // running with except for the KVM control signals. We'll - // sometimes need to raise the KVM_TIMER_SIGNAL to cause immediate - // exits from KVM after servicing IO requests. See kvmRun(). - sigdelset(&sigset, KVM_TIMER_SIGNAL); - sigdelset(&sigset, KVM_INST_SIGNAL); + // running with except for the KVM control signal. We'll sometimes + // need to raise the KVM_KICK_SIGNAL to cause immediate exits from + // KVM after servicing IO requests. See kvmRun(). + sigdelset(&sigset, KVM_KICK_SIGNAL); setSignalMask(&sigset); // Mask our control signals so they aren't delivered unless we're // actually executing inside KVM. - sigaddset(&sigset, KVM_TIMER_SIGNAL); - sigaddset(&sigset, KVM_INST_SIGNAL); + sigaddset(&sigset, KVM_KICK_SIGNAL); if (pthread_sigmask(SIG_SETMASK, &sigset, NULL) == -1) panic("KVM: Failed mask the KVM control signals\n"); } @@ -1266,7 +1238,7 @@ BaseKvmCPU::setupInstCounter(uint64_t period) hwCycles); if (period) - hwInstructions.enableSignals(KVM_INST_SIGNAL); + hwInstructions.enableSignals(KVM_KICK_SIGNAL); activeInstPeriod = period; } diff --git a/src/cpu/kvm/base.hh b/src/cpu/kvm/base.hh index 8191d9d92..b987f6a3e 100644 --- a/src/cpu/kvm/base.hh +++ b/src/cpu/kvm/base.hh @@ -40,8 +40,10 @@ #ifndef __CPU_KVM_BASE_HH__ #define __CPU_KVM_BASE_HH__ -#include <memory> +#include <pthread.h> + #include <csignal> +#include <memory> #include "base/statistics.hh" #include "cpu/kvm/perfevent.hh" @@ -50,11 +52,8 @@ #include "cpu/base.hh" #include "cpu/simple_thread.hh" -/** Signal to use to trigger time-based exits from KVM */ -#define KVM_TIMER_SIGNAL SIGRTMIN - -/** Signal to use to trigger instruction-based exits from KVM */ -#define KVM_INST_SIGNAL (SIGRTMIN+1) +/** Signal to use to trigger exits from KVM */ +#define KVM_KICK_SIGNAL SIGRTMIN // forward declarations class ThreadContext; @@ -115,6 +114,14 @@ class BaseKvmCPU : public BaseCPU virtual void dump(); /** + * Force an exit from KVM. + * + * Send a signal to the thread owning this vCPU to get it to exit + * from KVM. Ignored if the vCPU is not executing. + */ + void kick() const { pthread_kill(vcpuThread, KVM_KICK_SIGNAL); } + + /** * A cached copy of a thread's state in the form of a SimpleThread * object. * @@ -585,6 +592,9 @@ class BaseKvmCPU : public BaseCPU /** KVM internal ID of the vCPU */ const long vcpuID; + /** ID of the vCPU thread */ + pthread_t vcpuThread; + private: struct TickEvent : public Event { |