sanchayanmaity/gem5
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity
gem5/src/cpu/kvm/base.cc
Michael LeBeane 443da2c030 kvm: Support timing accesses for KVM cpu 
This patch enables timing accesses for KVM cpu.  A new state,
RunningMMIOPending, is added to indicate that there are outstanding timing
requests generated by KVM in the system.  KVM's tick() is disabled and the
simulation does not enter into KVM until all outstanding timing requests have
completed.  The main motivation for this is to allow KVM CPU to perform MMIO
in Ruby, since Ruby does not support atomic accesses.
2016-09-13 23:20:03 -04:00

1395 lines
40 KiB
C++
Raw Blame History

/*
* Copyright (c) 2012, 2015 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Andreas Sandberg
*/
#include <linux/kvm.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <cerrno>
#include <csignal>
#include <ostream>
#include "arch/mmapped_ipr.hh"
#include "arch/utility.hh"
#include "cpu/kvm/base.hh"
#include "debug/Checkpoint.hh"
#include "debug/Drain.hh"
#include "debug/Kvm.hh"
#include "debug/KvmIO.hh"
#include "debug/KvmRun.hh"
#include "params/BaseKvmCPU.hh"
#include "sim/process.hh"
#include "sim/system.hh"
#include <signal.h>
/* Used by some KVM macros */
#define PAGE_SIZE pageSize
BaseKvmCPU::BaseKvmCPU(BaseKvmCPUParams *params)
: BaseCPU(params),
vm(*params->kvmVM),
_status(Idle),
dataPort(name() + ".dcache_port", this),
instPort(name() + ".icache_port", this),
alwaysSyncTC(params->alwaysSyncTC),
threadContextDirty(true),
kvmStateDirty(false),
vcpuID(vm.allocVCPUID()), vcpuFD(-1), vcpuMMapSize(0),
_kvmRun(NULL), mmioRing(NULL),
pageSize(sysconf(_SC_PAGE_SIZE)),
tickEvent(*this),
activeInstPeriod(0),
perfControlledByTimer(params->usePerfOverflow),
hostFactor(params->hostFactor),
ctrInsts(0)
{
if (pageSize == -1)
panic("KVM: Failed to determine host page size (%i)\n",
errno);
if (FullSystem)
thread = new SimpleThread(this, 0, params->system, params->itb, params->dtb,
params->isa[0]);
else
thread = new SimpleThread(this, /* thread_num */ 0, params->system,
params->workload[0], params->itb,
params->dtb, params->isa[0]);
thread->setStatus(ThreadContext::Halted);
tc = thread->getTC();
threadContexts.push_back(tc);
}
BaseKvmCPU::~BaseKvmCPU()
{
if (_kvmRun)
munmap(_kvmRun, vcpuMMapSize);
close(vcpuFD);
}
void
BaseKvmCPU::init()
{
BaseCPU::init();
if (numThreads != 1)
fatal("KVM: Multithreading not supported");
tc->initMemProxies(tc);
// initialize CPU, including PC
if (FullSystem && !switchedOut())
TheISA::initCPU(tc, tc->contextId());
}
void
BaseKvmCPU::startup()
{
const BaseKvmCPUParams * const p(
dynamic_cast<const BaseKvmCPUParams *>(params()));
Kvm &kvm(*vm.kvm);
BaseCPU::startup();
assert(vcpuFD == -1);
// Tell the VM that a CPU is about to start.
vm.cpuStartup();
// We can't initialize KVM CPUs in BaseKvmCPU::init() since we are
// not guaranteed that the parent KVM VM has initialized at that
// point. Initialize virtual CPUs here instead.
vcpuFD = vm.createVCPU(vcpuID);
// Map the KVM run structure */
vcpuMMapSize = kvm.getVCPUMMapSize();
_kvmRun = (struct kvm_run *)mmap(0, vcpuMMapSize,
PROT_READ | PROT_WRITE, MAP_SHARED,
vcpuFD, 0);
if (_kvmRun == MAP_FAILED)
panic("KVM: Failed to map run data structure\n");
// Setup a pointer to the MMIO ring buffer if coalesced MMIO is
// available. The offset into the KVM's communication page is
// provided by the coalesced MMIO capability.
int mmioOffset(kvm.capCoalescedMMIO());
if (!p->useCoalescedMMIO) {
inform("KVM: Coalesced MMIO disabled by config.\n");
} else if (mmioOffset) {
inform("KVM: Coalesced IO available\n");
mmioRing = (struct kvm_coalesced_mmio_ring *)(
(char *)_kvmRun + (mmioOffset * pageSize));
} else {
inform("KVM: Coalesced not supported by host OS\n");
}
thread->startup();
Event *startupEvent(
new EventWrapper<BaseKvmCPU,
&BaseKvmCPU::startupThread>(this, true));
schedule(startupEvent, curTick());
}
BaseKvmCPU::Status
BaseKvmCPU::KVMCpuPort::nextIOState() const
{
return (activeMMIOReqs || pendingMMIOPkts.size())
? RunningMMIOPending : RunningServiceCompletion;
}
Tick
BaseKvmCPU::KVMCpuPort::submitIO(PacketPtr pkt)
{
if (cpu->system->isAtomicMode()) {
Tick delay = sendAtomic(pkt);
delete pkt->req;
delete pkt;
return delay;
} else {
if (pendingMMIOPkts.empty() && sendTimingReq(pkt)) {
activeMMIOReqs++;
} else {
pendingMMIOPkts.push(pkt);
}
// Return value is irrelevant for timing-mode accesses.
return 0;
}
}
bool
BaseKvmCPU::KVMCpuPort::recvTimingResp(PacketPtr pkt)
{
DPRINTF(KvmIO, "KVM: Finished timing request\n");
delete pkt->req;
delete pkt;
activeMMIOReqs--;
// We can switch back into KVM when all pending and in-flight MMIO
// operations have completed.
if (!(activeMMIOReqs || pendingMMIOPkts.size())) {
DPRINTF(KvmIO, "KVM: Finished all outstanding timing requests\n");
cpu->finishMMIOPending();
}
return true;
}
void
BaseKvmCPU::KVMCpuPort::recvReqRetry()
{
DPRINTF(KvmIO, "KVM: Retry for timing request\n");
assert(pendingMMIOPkts.size());
// Assuming that we can issue infinite requests this cycle is a bit
// unrealistic, but it's not worth modeling something more complex in
// KVM.
while (pendingMMIOPkts.size() && sendTimingReq(pendingMMIOPkts.front())) {
pendingMMIOPkts.pop();
activeMMIOReqs++;
}
}
void
BaseKvmCPU::finishMMIOPending()
{
assert(_status = RunningMMIOPending);
assert(!tickEvent.scheduled());
_status = RunningServiceCompletion;
schedule(tickEvent, nextCycle());
}
void
BaseKvmCPU::startupThread()
{
// Do thread-specific initialization. We need to setup signal
// delivery for counters and timers from within the thread that
// will execute the event queue to ensure that signals are
// delivered to the right threads.
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();
setupCounters();
if (p->usePerfOverflow)
runTimer.reset(new PerfKvmTimer(hwCycles,
KVM_KICK_SIGNAL,
p->hostFactor,
p->hostFreq));
else
runTimer.reset(new PosixKvmTimer(KVM_KICK_SIGNAL, CLOCK_MONOTONIC,
p->hostFactor,
p->hostFreq));
}
void
BaseKvmCPU::regStats()
{
using namespace Stats;
BaseCPU::regStats();
numInsts
.name(name() + ".committedInsts")
.desc("Number of instructions committed")
;
numVMExits
.name(name() + ".numVMExits")
.desc("total number of KVM exits")
;
numVMHalfEntries
.name(name() + ".numVMHalfEntries")
.desc("number of KVM entries to finalize pending operations")
;
numExitSignal
.name(name() + ".numExitSignal")
.desc("exits due to signal delivery")
;
numMMIO
.name(name() + ".numMMIO")
.desc("number of VM exits due to memory mapped IO")
;
numCoalescedMMIO
.name(name() + ".numCoalescedMMIO")
.desc("number of coalesced memory mapped IO requests")
;
numIO
.name(name() + ".numIO")
.desc("number of VM exits due to legacy IO")
;
numHalt
.name(name() + ".numHalt")
.desc("number of VM exits due to wait for interrupt instructions")
;
numInterrupts
.name(name() + ".numInterrupts")
.desc("number of interrupts delivered")
;
numHypercalls
.name(name() + ".numHypercalls")
.desc("number of hypercalls")
;
}
void
BaseKvmCPU::serializeThread(CheckpointOut &cp, ThreadID tid) const
{
if (DTRACE(Checkpoint)) {
DPRINTF(Checkpoint, "KVM: Serializing thread %i:\n", tid);
dump();
}
assert(tid == 0);
assert(_status == Idle);
thread->serialize(cp);
}
void
BaseKvmCPU::unserializeThread(CheckpointIn &cp, ThreadID tid)
{
DPRINTF(Checkpoint, "KVM: Unserialize thread %i:\n", tid);
assert(tid == 0);
assert(_status == Idle);
thread->unserialize(cp);
threadContextDirty = true;
}
DrainState
BaseKvmCPU::drain()
{
if (switchedOut())
return DrainState::Drained;
DPRINTF(Drain, "BaseKvmCPU::drain\n");
switch (_status) {
case Running:
// The base KVM code is normally ready when it is in the
// Running state, but the architecture specific code might be
// of a different opinion. This may happen when the CPU been
// notified of an event that hasn't been accepted by the vCPU
// yet.
if (!archIsDrained())
return DrainState::Draining;
// The state of the CPU is consistent, so we don't need to do
// anything special to drain it. We simply de-schedule the
// tick event and enter the Idle state to prevent nasty things
// like MMIOs from happening.
if (tickEvent.scheduled())
deschedule(tickEvent);
_status = Idle;
/** FALLTHROUGH */
case Idle:
// Idle, no need to drain
assert(!tickEvent.scheduled());
// Sync the thread context here since we'll need it when we
// switch CPUs or checkpoint the CPU.
syncThreadContext();
return DrainState::Drained;
case RunningServiceCompletion:
// The CPU has just requested a service that was handled in
// the RunningService state, but the results have still not
// been reported to the CPU. Now, we /could/ probably just
// update the register state ourselves instead of letting KVM
// handle it, but that would be tricky. Instead, we enter KVM
// and let it do its stuff.
DPRINTF(Drain, "KVM CPU is waiting for service completion, "
"requesting drain.\n");
return DrainState::Draining;
case RunningMMIOPending:
// We need to drain since there are in-flight timing accesses
DPRINTF(Drain, "KVM CPU is waiting for timing accesses to complete, "
"requesting drain.\n");
return DrainState::Draining;
case RunningService:
// We need to drain since the CPU is waiting for service (e.g., MMIOs)
DPRINTF(Drain, "KVM CPU is waiting for service, requesting drain.\n");
return DrainState::Draining;
default:
panic("KVM: Unhandled CPU state in drain()\n");
return DrainState::Drained;
}
}
void
BaseKvmCPU::drainResume()
{
assert(!tickEvent.scheduled());
// We might have been switched out. In that case, we don't need to
// do anything.
if (switchedOut())
return;
DPRINTF(Kvm, "drainResume\n");
verifyMemoryMode();
// The tick event is de-scheduled as a part of the draining
// process. Re-schedule it if the thread context is active.
if (tc->status() == ThreadContext::Active) {
schedule(tickEvent, nextCycle());
_status = Running;
} else {
_status = Idle;
}
}
void
BaseKvmCPU::notifyFork()
{
// We should have drained prior to forking, which means that the
// tick event shouldn't be scheduled and the CPU is idle.
assert(!tickEvent.scheduled());
assert(_status == Idle);
if (vcpuFD != -1) {
if (close(vcpuFD) == -1)
warn("kvm CPU: notifyFork failed to close vcpuFD\n");
if (_kvmRun)
munmap(_kvmRun, vcpuMMapSize);
vcpuFD = -1;
_kvmRun = NULL;
hwInstructions.detach();
hwCycles.detach();
}
}
void
BaseKvmCPU::switchOut()
{
DPRINTF(Kvm, "switchOut\n");
BaseCPU::switchOut();
// We should have drained prior to executing a switchOut, which
// means that the tick event shouldn't be scheduled and the CPU is
// idle.
assert(!tickEvent.scheduled());
assert(_status == Idle);
}
void
BaseKvmCPU::takeOverFrom(BaseCPU *cpu)
{
DPRINTF(Kvm, "takeOverFrom\n");
BaseCPU::takeOverFrom(cpu);
// We should have drained prior to executing a switchOut, which
// means that the tick event shouldn't be scheduled and the CPU is
// idle.
assert(!tickEvent.scheduled());
assert(_status == Idle);
assert(threadContexts.size() == 1);
// Force an update of the KVM state here instead of flagging the
// TC as dirty. This is not ideal from a performance point of
// view, but it makes debugging easier as it allows meaningful KVM
// state to be dumped before and after a takeover.
updateKvmState();
threadContextDirty = false;
}
void
BaseKvmCPU::verifyMemoryMode() const
{
if (!(system->bypassCaches())) {
fatal("The KVM-based CPUs requires the memory system to be in the "
"'noncaching' mode.\n");
}
}
void
BaseKvmCPU::wakeup(ThreadID tid)
{
DPRINTF(Kvm, "wakeup()\n");
// This method might have been called from another
// context. Migrate to this SimObject's event queue when
// delivering the wakeup signal.
EventQueue::ScopedMigration migrate(eventQueue());
// Kick the vCPU to get it to come out of KVM.
kick();
if (thread->status() != ThreadContext::Suspended)
return;
thread->activate();
}
void
BaseKvmCPU::activateContext(ThreadID thread_num)
{
DPRINTF(Kvm, "ActivateContext %d\n", thread_num);
assert(thread_num == 0);
assert(thread);
assert(_status == Idle);
assert(!tickEvent.scheduled());
numCycles += ticksToCycles(thread->lastActivate - thread->lastSuspend);
schedule(tickEvent, clockEdge(Cycles(0)));
_status = Running;
}
void
BaseKvmCPU::suspendContext(ThreadID thread_num)
{
DPRINTF(Kvm, "SuspendContext %d\n", thread_num);
assert(thread_num == 0);
assert(thread);
if (_status == Idle)
return;
assert(_status == Running || _status == RunningServiceCompletion);
// The tick event may no be scheduled if the quest has requested
// the monitor to wait for interrupts. The normal CPU models can
// get their tick events descheduled by quiesce instructions, but
// that can't happen here.
if (tickEvent.scheduled())
deschedule(tickEvent);
_status = Idle;
}
void
BaseKvmCPU::deallocateContext(ThreadID thread_num)
{
// for now, these are equivalent
suspendContext(thread_num);
}
void
BaseKvmCPU::haltContext(ThreadID thread_num)
{
// for now, these are equivalent
suspendContext(thread_num);
}
ThreadContext *
BaseKvmCPU::getContext(int tn)
{
assert(tn == 0);
syncThreadContext();
return tc;
}
Counter
BaseKvmCPU::totalInsts() const
{
return ctrInsts;
}
Counter
BaseKvmCPU::totalOps() const
{
hack_once("Pretending totalOps is equivalent to totalInsts()\n");
return ctrInsts;
}
void
BaseKvmCPU::dump() const
{
inform("State dumping not implemented.");
}
void
BaseKvmCPU::tick()
{
Tick delay(0);
assert(_status != Idle && _status != RunningMMIOPending);
switch (_status) {
case RunningService:
// handleKvmExit() will determine the next state of the CPU
delay = handleKvmExit();
if (tryDrain())
_status = Idle;
break;
case RunningServiceCompletion:
case Running: {
const uint64_t nextInstEvent(
!comInstEventQueue[0]->empty() ?
comInstEventQueue[0]->nextTick() : UINT64_MAX);
// Enter into KVM and complete pending IO instructions if we
// have an instruction event pending.
const Tick ticksToExecute(
nextInstEvent > ctrInsts ?
curEventQueue()->nextTick() - curTick() : 0);
if (alwaysSyncTC)
threadContextDirty = true;
// We might need to update the KVM state.
syncKvmState();
// Setup any pending instruction count breakpoints using
// PerfEvent if we are going to execute more than just an IO
// completion.
if (ticksToExecute > 0)
setupInstStop();
DPRINTF(KvmRun, "Entering KVM...\n");
if (drainState() == DrainState::Draining) {
// Force an immediate exit from KVM after completing
// pending operations. The architecture-specific code
// takes care to run until it is in a state where it can
// safely be drained.
delay = kvmRunDrain();
} else {
delay = kvmRun(ticksToExecute);
}
// The CPU might have been suspended before entering into
// KVM. Assume that the CPU was suspended /before/ entering
// into KVM and skip the exit handling.
if (_status == Idle)
break;
// Entering into KVM implies that we'll have to reload the thread
// context from KVM if we want to access it. Flag the KVM state as
// dirty with respect to the cached thread context.
kvmStateDirty = true;
if (alwaysSyncTC)
syncThreadContext();
// Enter into the RunningService state unless the
// simulation was stopped by a timer.
if (_kvmRun->exit_reason != KVM_EXIT_INTR) {
_status = RunningService;
} else {
++numExitSignal;
_status = Running;
}
// Service any pending instruction events. The vCPU should
// have exited in time for the event using the instruction
// counter configured by setupInstStop().
comInstEventQueue[0]->serviceEvents(ctrInsts);
system->instEventQueue.serviceEvents(system->totalNumInsts);
if (tryDrain())
_status = Idle;
} break;
default:
panic("BaseKvmCPU entered tick() in an illegal state (%i)\n",
_status);
}
// Schedule a new tick if we are still running
if (_status != Idle && _status != RunningMMIOPending)
schedule(tickEvent, clockEdge(ticksToCycles(delay)));
}
Tick
BaseKvmCPU::kvmRunDrain()
{
// By default, the only thing we need to drain is a pending IO
// operation which assumes that we are in the
// RunningServiceCompletion or RunningMMIOPending state.
assert(_status == RunningServiceCompletion ||
_status == RunningMMIOPending);
// Deliver the data from the pending IO operation and immediately
// exit.
return kvmRun(0);
}
uint64_t
BaseKvmCPU::getHostCycles() const
{
return hwCycles.read();
}
Tick
BaseKvmCPU::kvmRun(Tick ticks)
{
Tick ticksExecuted;
fatal_if(vcpuFD == -1,
"Trying to run a KVM CPU in a forked child process. "
"This is not supported.\n");
DPRINTF(KvmRun, "KVM: Executing for %i ticks\n", ticks);
if (ticks == 0) {
// Settings ticks == 0 is a special case which causes an entry
// into KVM that finishes pending operations (e.g., IO) and
// then immediately exits.
DPRINTF(KvmRun, "KVM: Delivering IO without full guest entry\n");
++numVMHalfEntries;
// 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().
kick();
// 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 (other than completing half-executed IO
// instructions) in the guest.
ioctlRun();
// We always execute at least one cycle to prevent the
// BaseKvmCPU::tick() to be rescheduled on the same tick
// twice.
ticksExecuted = clockPeriod();
} else {
// This method is executed as a result of a tick event. That
// means that the event queue will be locked when entering the
// method. We temporarily unlock the event queue to allow
// other threads to steal control of this thread to inject
// interrupts. They will typically lock the queue and then
// force an exit from KVM by kicking the vCPU.
EventQueue::ScopedRelease release(curEventQueue());
if (ticks < runTimer->resolution()) {
DPRINTF(KvmRun, "KVM: Adjusting tick count (%i -> %i)\n",
ticks, runTimer->resolution());
ticks = runTimer->resolution();
}
// Get hardware statistics after synchronizing contexts. The KVM
// state update might affect guest cycle counters.
uint64_t baseCycles(getHostCycles());
uint64_t baseInstrs(hwInstructions.read());
// Arm the run timer and start the cycle timer if it isn't
// controlled by the overflow timer. Starting/stopping the cycle
// timer automatically starts the other perf timers as they are in
// the same counter group.
runTimer->arm(ticks);
if (!perfControlledByTimer)
hwCycles.start();
ioctlRun();
runTimer->disarm();
if (!perfControlledByTimer)
hwCycles.stop();
// 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_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);
/* Update statistics */
numCycles += simCyclesExecuted;;
numInsts += instsExecuted;
ctrInsts += instsExecuted;
system->totalNumInsts += instsExecuted;
DPRINTF(KvmRun,
"KVM: Executed %i instructions in %i cycles "
"(%i ticks, sim cycles: %i).\n",
instsExecuted, hostCyclesExecuted, ticksExecuted, simCyclesExecuted);
}
++numVMExits;
return ticksExecuted + flushCoalescedMMIO();
}
void
BaseKvmCPU::kvmNonMaskableInterrupt()
{
++numInterrupts;
if (ioctl(KVM_NMI) == -1)
panic("KVM: Failed to deliver NMI to virtual CPU\n");
}
void
BaseKvmCPU::kvmInterrupt(const struct kvm_interrupt &interrupt)
{
++numInterrupts;
if (ioctl(KVM_INTERRUPT, (void *)&interrupt) == -1)
panic("KVM: Failed to deliver interrupt to virtual CPU\n");
}
void
BaseKvmCPU::getRegisters(struct kvm_regs &regs) const
{
if (ioctl(KVM_GET_REGS, &regs) == -1)
panic("KVM: Failed to get guest registers\n");
}
void
BaseKvmCPU::setRegisters(const struct kvm_regs &regs)
{
if (ioctl(KVM_SET_REGS, (void *)&regs) == -1)
panic("KVM: Failed to set guest registers\n");
}
void
BaseKvmCPU::getSpecialRegisters(struct kvm_sregs &regs) const
{
if (ioctl(KVM_GET_SREGS, &regs) == -1)
panic("KVM: Failed to get guest special registers\n");
}
void
BaseKvmCPU::setSpecialRegisters(const struct kvm_sregs &regs)
{
if (ioctl(KVM_SET_SREGS, (void *)&regs) == -1)
panic("KVM: Failed to set guest special registers\n");
}
void
BaseKvmCPU::getFPUState(struct kvm_fpu &state) const
{
if (ioctl(KVM_GET_FPU, &state) == -1)
panic("KVM: Failed to get guest FPU state\n");
}
void
BaseKvmCPU::setFPUState(const struct kvm_fpu &state)
{
if (ioctl(KVM_SET_FPU, (void *)&state) == -1)
panic("KVM: Failed to set guest FPU state\n");
}
void
BaseKvmCPU::setOneReg(uint64_t id, const void *addr)
{
#ifdef KVM_SET_ONE_REG
struct kvm_one_reg reg;
reg.id = id;
reg.addr = (uint64_t)addr;
if (ioctl(KVM_SET_ONE_REG, &reg) == -1) {
panic("KVM: Failed to set register (0x%x) value (errno: %i)\n",
id, errno);
}
#else
panic("KVM_SET_ONE_REG is unsupported on this platform.\n");
#endif
}
void
BaseKvmCPU::getOneReg(uint64_t id, void *addr) const
{
#ifdef KVM_GET_ONE_REG
struct kvm_one_reg reg;
reg.id = id;
reg.addr = (uint64_t)addr;
if (ioctl(KVM_GET_ONE_REG, &reg) == -1) {
panic("KVM: Failed to get register (0x%x) value (errno: %i)\n",
id, errno);
}
#else
panic("KVM_GET_ONE_REG is unsupported on this platform.\n");
#endif
}
std::string
BaseKvmCPU::getAndFormatOneReg(uint64_t id) const
{
#ifdef KVM_GET_ONE_REG
std::ostringstream ss;
ss.setf(std::ios::hex, std::ios::basefield);
ss.setf(std::ios::showbase);
#define HANDLE_INTTYPE(len) \
case KVM_REG_SIZE_U ## len: { \
uint ## len ## _t value; \
getOneReg(id, &value); \
ss << value; \
} break
#define HANDLE_ARRAY(len) \
case KVM_REG_SIZE_U ## len: { \
uint8_t value[len / 8]; \
getOneReg(id, value); \
ccprintf(ss, "[0x%x", value[0]); \
for (int i = 1; i < len / 8; ++i) \
ccprintf(ss, ", 0x%x", value[i]); \
ccprintf(ss, "]"); \
} break
switch (id & KVM_REG_SIZE_MASK) {
HANDLE_INTTYPE(8);
HANDLE_INTTYPE(16);
HANDLE_INTTYPE(32);
HANDLE_INTTYPE(64);
HANDLE_ARRAY(128);
HANDLE_ARRAY(256);
HANDLE_ARRAY(512);
HANDLE_ARRAY(1024);
default:
ss << "??";
}
#undef HANDLE_INTTYPE
#undef HANDLE_ARRAY
return ss.str();
#else
panic("KVM_GET_ONE_REG is unsupported on this platform.\n");
#endif
}
void
BaseKvmCPU::syncThreadContext()
{
if (!kvmStateDirty)
return;
assert(!threadContextDirty);
updateThreadContext();
kvmStateDirty = false;
}
void
BaseKvmCPU::syncKvmState()
{
if (!threadContextDirty)
return;
assert(!kvmStateDirty);
updateKvmState();
threadContextDirty = false;
}
Tick
BaseKvmCPU::handleKvmExit()
{
DPRINTF(KvmRun, "handleKvmExit (exit_reason: %i)\n", _kvmRun->exit_reason);
assert(_status == RunningService);
// Switch into the running state by default. Individual handlers
// can override this.
_status = Running;
switch (_kvmRun->exit_reason) {
case KVM_EXIT_UNKNOWN:
return handleKvmExitUnknown();
case KVM_EXIT_EXCEPTION:
return handleKvmExitException();
case KVM_EXIT_IO:
{
++numIO;
Tick ticks = handleKvmExitIO();
_status = dataPort.nextIOState();
return ticks;
}
case KVM_EXIT_HYPERCALL:
++numHypercalls;
return handleKvmExitHypercall();
case KVM_EXIT_HLT:
/* The guest has halted and is waiting for interrupts */
DPRINTF(Kvm, "handleKvmExitHalt\n");
++numHalt;
// Suspend the thread until the next interrupt arrives
thread->suspend();
// This is actually ignored since the thread is suspended.
return 0;
case KVM_EXIT_MMIO:
{
/* Service memory mapped IO requests */
DPRINTF(KvmIO, "KVM: Handling MMIO (w: %u, addr: 0x%x, len: %u)\n",
_kvmRun->mmio.is_write,
_kvmRun->mmio.phys_addr, _kvmRun->mmio.len);
++numMMIO;
Tick ticks = doMMIOAccess(_kvmRun->mmio.phys_addr, _kvmRun->mmio.data,
_kvmRun->mmio.len, _kvmRun->mmio.is_write);
// doMMIOAccess could have triggered a suspend, in which case we don't
// want to overwrite the _status.
if (_status != Idle)
_status = dataPort.nextIOState();
return ticks;
}
case KVM_EXIT_IRQ_WINDOW_OPEN:
return handleKvmExitIRQWindowOpen();
case KVM_EXIT_FAIL_ENTRY:
return handleKvmExitFailEntry();
case KVM_EXIT_INTR:
/* KVM was interrupted by a signal, restart it in the next
* tick. */
return 0;
case KVM_EXIT_INTERNAL_ERROR:
panic("KVM: Internal error (suberror: %u)\n",
_kvmRun->internal.suberror);
default:
dump();
panic("KVM: Unexpected exit (exit_reason: %u)\n", _kvmRun->exit_reason);
}
}
Tick
BaseKvmCPU::handleKvmExitIO()
{
panic("KVM: Unhandled guest IO (dir: %i, size: %i, port: 0x%x, count: %i)\n",
_kvmRun->io.direction, _kvmRun->io.size,
_kvmRun->io.port, _kvmRun->io.count);
}
Tick
BaseKvmCPU::handleKvmExitHypercall()
{
panic("KVM: Unhandled hypercall\n");
}
Tick
BaseKvmCPU::handleKvmExitIRQWindowOpen()
{
warn("KVM: Unhandled IRQ window.\n");
return 0;
}
Tick
BaseKvmCPU::handleKvmExitUnknown()
{
dump();
panic("KVM: Unknown error when starting vCPU (hw reason: 0x%llx)\n",
_kvmRun->hw.hardware_exit_reason);
}
Tick
BaseKvmCPU::handleKvmExitException()
{
dump();
panic("KVM: Got exception when starting vCPU "
"(exception: %u, error_code: %u)\n",
_kvmRun->ex.exception, _kvmRun->ex.error_code);
}
Tick
BaseKvmCPU::handleKvmExitFailEntry()
{
dump();
panic("KVM: Failed to enter virtualized mode (hw reason: 0x%llx)\n",
_kvmRun->fail_entry.hardware_entry_failure_reason);
}
Tick
BaseKvmCPU::doMMIOAccess(Addr paddr, void *data, int size, bool write)
{
ThreadContext *tc(thread->getTC());
syncThreadContext();
RequestPtr mmio_req = new Request(paddr, size, Request::UNCACHEABLE,
dataMasterId());
mmio_req->setContext(tc->contextId());
// Some architectures do need to massage physical addresses a bit
// before they are inserted into the memory system. This enables
// APIC accesses on x86 and m5ops where supported through a MMIO
// interface.
BaseTLB::Mode tlb_mode(write ? BaseTLB::Write : BaseTLB::Read);
Fault fault(tc->getDTBPtr()->finalizePhysical(mmio_req, tc, tlb_mode));
if (fault != NoFault)
warn("Finalization of MMIO address failed: %s\n", fault->name());
const MemCmd cmd(write ? MemCmd::WriteReq : MemCmd::ReadReq);
PacketPtr pkt = new Packet(mmio_req, cmd);
pkt->dataStatic(data);
if (mmio_req->isMmappedIpr()) {
// We currently assume that there is no need to migrate to a
// different event queue when doing IPRs. Currently, IPRs are
// only used for m5ops, so it should be a valid assumption.
const Cycles ipr_delay(write ?
TheISA::handleIprWrite(tc, pkt) :
TheISA::handleIprRead(tc, pkt));
threadContextDirty = true;
delete pkt->req;
delete pkt;
return clockPeriod() * ipr_delay;
} else {
// Temporarily lock and migrate to the event queue of the
// VM. This queue is assumed to "own" all devices we need to
// access if running in multi-core mode.
EventQueue::ScopedMigration migrate(vm.eventQueue());
return dataPort.submitIO(pkt);
}
}
void
BaseKvmCPU::setSignalMask(const sigset_t *mask)
{
std::unique_ptr<struct kvm_signal_mask> kvm_mask;
if (mask) {
kvm_mask.reset((struct kvm_signal_mask *)operator new(
sizeof(struct kvm_signal_mask) + sizeof(*mask)));
// The kernel and the user-space headers have different ideas
// about the size of sigset_t. This seems like a massive hack,
// but is actually what qemu does.
assert(sizeof(*mask) >= 8);
kvm_mask->len = 8;
memcpy(kvm_mask->sigset, mask, kvm_mask->len);
}
if (ioctl(KVM_SET_SIGNAL_MASK, (void *)kvm_mask.get()) == -1)
panic("KVM: Failed to set vCPU signal mask (errno: %i)\n",
errno);
}
int
BaseKvmCPU::ioctl(int request, long p1) const
{
if (vcpuFD == -1)
panic("KVM: CPU ioctl called before initialization\n");
return ::ioctl(vcpuFD, request, p1);
}
Tick
BaseKvmCPU::flushCoalescedMMIO()
{
if (!mmioRing)
return 0;
DPRINTF(KvmIO, "KVM: Flushing the coalesced MMIO ring buffer\n");
// TODO: We might need to do synchronization when we start to
// support multiple CPUs
Tick ticks(0);
while (mmioRing->first != mmioRing->last) {
struct kvm_coalesced_mmio &ent(
mmioRing->coalesced_mmio[mmioRing->first]);
DPRINTF(KvmIO, "KVM: Handling coalesced MMIO (addr: 0x%x, len: %u)\n",
ent.phys_addr, ent.len);
++numCoalescedMMIO;
ticks += doMMIOAccess(ent.phys_addr, ent.data, ent.len, true);
mmioRing->first = (mmioRing->first + 1) % KVM_COALESCED_MMIO_MAX;
}
return ticks;
}
/**
* Dummy handler for KVM kick signals.
*
* @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
* setupSignalHandler() and kvmRun() for details about KVM signal
* handling.
*/
static void
onKickSignal(int signo, siginfo_t *si, void *data)
{
}
void
BaseKvmCPU::setupSignalHandler()
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = onKickSignal;
sa.sa_flags = SA_SIGINFO | SA_RESTART;
if (sigaction(KVM_KICK_SIGNAL, &sa, NULL) == -1)
panic("KVM: Failed to setup vCPU timer 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 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_KICK_SIGNAL);
if (pthread_sigmask(SIG_SETMASK, &sigset, NULL) == -1)
panic("KVM: Failed mask the KVM control signals\n");
}
bool
BaseKvmCPU::discardPendingSignal(int signum) const
{
int discardedSignal;
// Setting the timeout to zero causes sigtimedwait to return
// immediately.
struct timespec timeout;
timeout.tv_sec = 0;
timeout.tv_nsec = 0;
sigset_t sigset;
sigemptyset(&sigset);
sigaddset(&sigset, signum);
do {
discardedSignal = sigtimedwait(&sigset, NULL, &timeout);
} while (discardedSignal == -1 && errno == EINTR);
if (discardedSignal == signum)
return true;
else if (discardedSignal == -1 && errno == EAGAIN)
return false;
else
panic("Unexpected return value from sigtimedwait: %i (errno: %i)\n",
discardedSignal, errno);
}
void
BaseKvmCPU::setupCounters()
{
DPRINTF(Kvm, "Attaching cycle counter...\n");
PerfKvmCounterConfig cfgCycles(PERF_TYPE_HARDWARE,
PERF_COUNT_HW_CPU_CYCLES);
cfgCycles.disabled(true)
.pinned(true);
// Try to exclude the host. We set both exclude_hv and
// exclude_host since different architectures use slightly
// different APIs in the kernel.
cfgCycles.exclude_hv(true)
.exclude_host(true);
if (perfControlledByTimer) {
// We need to configure the cycles counter to send overflows
// since we are going to use it to trigger timer signals that
// trap back into m5 from KVM. In practice, this means that we
// need to set some non-zero sample period that gets
// overridden when the timer is armed.
cfgCycles.wakeupEvents(1)
.samplePeriod(42);
}
hwCycles.attach(cfgCycles,
0); // TID (0 => currentThread)
setupInstCounter();
}
bool
BaseKvmCPU::tryDrain()
{
if (drainState() != DrainState::Draining)
return false;
if (!archIsDrained()) {
DPRINTF(Drain, "tryDrain: Architecture code is not ready.\n");
return false;
}
if (_status == Idle || _status == Running) {
DPRINTF(Drain,
"tryDrain: CPU transitioned into the Idle state, drain done\n");
signalDrainDone();
return true;
} else {
DPRINTF(Drain, "tryDrain: CPU not ready.\n");
return false;
}
}
void
BaseKvmCPU::ioctlRun()
{
if (ioctl(KVM_RUN) == -1) {
if (errno != EINTR)
panic("KVM: Failed to start virtual CPU (errno: %i)\n",
errno);
}
}
void
BaseKvmCPU::setupInstStop()
{
if (comInstEventQueue[0]->empty()) {
setupInstCounter(0);
} else {
const uint64_t next(comInstEventQueue[0]->nextTick());
assert(next > ctrInsts);
setupInstCounter(next - ctrInsts);
}
}
void
BaseKvmCPU::setupInstCounter(uint64_t period)
{
// No need to do anything if we aren't attaching for the first
// time or the period isn't changing.
if (period == activeInstPeriod && hwInstructions.attached())
return;
PerfKvmCounterConfig cfgInstructions(PERF_TYPE_HARDWARE,
PERF_COUNT_HW_INSTRUCTIONS);
// Try to exclude the host. We set both exclude_hv and
// exclude_host since different architectures use slightly
// different APIs in the kernel.
cfgInstructions.exclude_hv(true)
.exclude_host(true);
if (period) {
// Setup a sampling counter if that has been requested.
cfgInstructions.wakeupEvents(1)
.samplePeriod(period);
}
// We need to detach and re-attach the counter to reliably change
// sampling settings. See PerfKvmCounter::period() for details.
if (hwInstructions.attached())
hwInstructions.detach();
assert(hwCycles.attached());
hwInstructions.attach(cfgInstructions,
0, // TID (0 => currentThread)
hwCycles);
if (period)
hwInstructions.enableSignals(KVM_KICK_SIGNAL);
activeInstPeriod = period;
}
Reference in a new issue View git blame Copy permalink