kvm: Basic support for hardware virtualized CPUs

This changeset introduces the architecture independent parts required
to support KVM-accelerated CPUs. It introduces two new simulation
objects:

KvmVM -- The KVM VM is a component shared between all CPUs in a shared
         memory domain. It is typically instantiated as a child of the
         system object in the simulation hierarchy. It provides access
         to KVM VM specific interfaces.

BaseKvmCPU -- Abstract base class for all KVM-based CPUs. Architecture
	      dependent CPU implementations inherit from this class
	      and implement the following methods:

                * updateKvmState() -- Update the
                  architecture-dependent KVM state from the gem5
                  thread context associated with the CPU.

                * updateThreadContext() -- Update the thread context
                  from the architecture-dependent KVM state.

                * dump() -- Dump the KVM state using (optional).

	      In order to deliver interrupts to the guest, CPU
	      implementations typically override the tick() method and
	      check for, and deliver, interrupts prior to entering
	      KVM.

Hardware-virutalized CPU currently have the following limitations:
 * SE mode is not supported.
 * PC events are not supported.
 * Timing statistics are currently very limited. The current approach
   simply scales the host cycles with a user-configurable factor.
 * The simulated system must not contain any caches.
 * Since cycle counts are approximate, there is no way to request an
   exact number of cycles (or instructions) to be executed by the CPU.
 * Hardware virtualized CPUs and gem5 CPUs must not execute at the
   same time in the same simulator instance.
 * Only single-CPU systems can be simulated.
 * Remote GDB connections to the guest system are not supported.

Additionally, m5ops requires an architecture specific interface and
might not be supported.

1 files changed, 246 insertions, 0 deletions

diff --git a/src/cpu/kvm/perfevent.cc b/src/cpu/kvm/perfevent.cc
new file mode 100644
index 000000000..cd8b970e9
--- /dev/null
+++ b/src/cpu/kvm/perfevent.cc
@@ -0,0 +1,246 @@
+/*
+ * Copyright (c) 2012 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 <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <syscall.h>
+#include <unistd.h>
+
+#include <cassert>
+#include <cerrno>
+#include <csignal>
+#include <cstring>
+
+#include "base/misc.hh"
+#include "perfevent.hh"
+
+PerfKvmCounterConfig::PerfKvmCounterConfig(uint32_t type, uint64_t config)
+{
+    memset(&attr, 0, sizeof(attr));
+
+    attr.size = PERF_ATTR_SIZE_VER0;
+    attr.type = type;
+    attr.config = config;
+}
+
+PerfKvmCounterConfig::~PerfKvmCounterConfig()
+{
+}
+
+
+PerfKvmCounter::PerfKvmCounter(PerfKvmCounterConfig &config, pid_t tid)
+    : fd(-1), ringBuffer(NULL), pageSize(-1)
+{
+    attach(config, tid, -1);
+}
+
+PerfKvmCounter::PerfKvmCounter(PerfKvmCounterConfig &config,
+                         pid_t tid, const PerfKvmCounter &parent)
+    : fd(-1), ringBuffer(NULL), pageSize(-1)
+{
+    attach(config, tid, parent);
+}
+
+PerfKvmCounter::PerfKvmCounter()
+    : fd(-1), ringBuffer(NULL), pageSize(-1)
+{
+}
+
+PerfKvmCounter::~PerfKvmCounter()
+{
+    if (attached())
+        detach();
+}
+
+void
+PerfKvmCounter::detach()
+{
+    assert(attached());
+
+    if (munmap(ringBuffer, ringNumPages * pageSize) == -1)
+        warn("PerfKvmCounter: Failed to unmap ring buffer (%i)\n",
+             errno);
+    close(fd);
+
+    fd = -1;
+    ringBuffer = NULL;
+}
+
+void
+PerfKvmCounter::start()
+{
+    if (ioctl(PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP) == -1)
+        panic("KVM: Failed to enable performance counters (%i)\n", errno);
+}
+
+void
+PerfKvmCounter::stop()
+{
+    if (ioctl(PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP) == -1)
+        panic("KVM: Failed to disable performance counters (%i)\n", errno);
+}
+
+void
+PerfKvmCounter::period(uint64_t period)
+{
+    if (ioctl(PERF_EVENT_IOC_PERIOD, &period) == -1)
+        panic("KVM: Failed to set period of performance counter (%i)\n", errno);
+}
+
+void
+PerfKvmCounter::refresh(int refresh)
+{
+    if (ioctl(PERF_EVENT_IOC_REFRESH, refresh) == -1)
+        panic("KVM: Failed to refresh performance counter (%i)\n", errno);
+}
+
+uint64_t
+PerfKvmCounter::read() const
+{
+    uint64_t value;
+
+    read(&value, sizeof(uint64_t));
+    return value;
+}
+
+void
+PerfKvmCounter::enableSignals(pid_t tid, int signal)
+{
+    struct f_owner_ex sigowner;
+
+    sigowner.type = F_OWNER_TID;
+    sigowner.pid = tid;
+
+    if (fcntl(F_SETOWN_EX, &sigowner) == -1 ||
+        fcntl(F_SETSIG, signal) == -1 ||
+        fcntl(F_SETFL, O_ASYNC) == -1)
+        panic("PerfKvmCounter: Failed to enable signals for counter (%i)\n",
+              errno);
+}
+
+void
+PerfKvmCounter::attach(PerfKvmCounterConfig &config,
+                    pid_t tid, int group_fd)
+{
+    assert(!attached());
+
+    fd = syscall(__NR_perf_event_open,
+                 &config.attr, tid,
+                 -1, // CPU (-1 => Any CPU that the task happens to run on)
+                 group_fd,
+                 0); // Flags
+    if (fd == -1)
+        panic("PerfKvmCounter::open failed (%i)\n", errno);
+
+    mmapPerf(1);
+}
+
+pid_t
+PerfKvmCounter::gettid()
+{
+    return syscall(__NR_gettid);
+}
+
+void
+PerfKvmCounter::mmapPerf(int pages)
+{
+    assert(attached());
+    assert(ringBuffer == NULL);
+
+    if (pageSize == -1) {
+        pageSize = sysconf(_SC_PAGE_SIZE);
+        if (pageSize == -1)
+            panic("PerfKvmCounter: Failed to determine page size (%i)\n",
+                  errno);
+    }
+
+    ringNumPages = pages + 1;
+    ringBuffer = (struct perf_event_mmap_page *)mmap(
+        NULL, ringNumPages * 4096,
+        PROT_READ | PROT_WRITE, MAP_SHARED,
+        fd, 0);
+    if (ringBuffer == MAP_FAILED)
+        panic("PerfKvmCounter: MMAP failed (%i)\n",
+              errno);
+}
+
+int
+PerfKvmCounter::fcntl(int cmd, long p1)
+{
+    assert(attached());
+    return ::fcntl(fd, cmd, p1);
+}
+
+int
+PerfKvmCounter::ioctl(int request, long p1)
+{
+    assert(attached());
+    return ::ioctl(fd, request, p1);
+}
+
+void
+PerfKvmCounter::read(void *buf, size_t size) const
+{
+    char *_buf = (char *)buf;
+    size_t _size = size;
+
+    assert(attached());
+
+    do {
+        ssize_t ret;
+        ret = ::read(fd, _buf, _size);
+        switch (ret) {
+          case -1:
+            if (errno != EAGAIN)
+                panic("PerfKvmCounter::read failed (%i)\n", errno);
+            break;
+
+          case 0:
+            panic("PerfKvmCounter::read unexpected EOF.\n");
+
+          default:
+            _size -= ret;
+            _buf += ret;
+            break;
+        }
+    } while(_size);
+}