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-rw-r--r--src/cpu/kvm/base.cc80
-rw-r--r--src/cpu/kvm/base.hh22
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
{