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, 370 insertions, 0 deletions

diff --git a/src/cpu/kvm/vm.cc b/src/cpu/kvm/vm.cc
new file mode 100644
index 000000000..8e7f6462d
--- /dev/null
+++ b/src/cpu/kvm/vm.cc
@@ -0,0 +1,370 @@
+/*
+ * 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 <linux/kvm.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <cerrno>
+
+#include "cpu/kvm/vm.hh"
+#include "debug/Kvm.hh"
+#include "params/KvmVM.hh"
+#include "sim/system.hh"
+
+#define EXPECTED_KVM_API_VERSION 12
+
+#if EXPECTED_KVM_API_VERSION != KVM_API_VERSION
+#error Unsupported KVM version
+#endif
+
+Kvm *Kvm::instance = NULL;
+
+Kvm::Kvm()
+    : kvmFD(-1), apiVersion(-1), vcpuMMapSize(0)
+{
+    kvmFD = ::open("/dev/kvm", O_RDWR);
+    if (kvmFD == -1)
+        fatal("KVM: Failed to open /dev/kvm\n");
+
+    apiVersion = ioctl(KVM_GET_API_VERSION);
+    if (apiVersion != EXPECTED_KVM_API_VERSION)
+        fatal("KVM: Incompatible API version\n");
+
+    vcpuMMapSize = ioctl(KVM_GET_VCPU_MMAP_SIZE);
+    if (vcpuMMapSize == -1)
+        panic("KVM: Failed to get virtual CPU MMAP size\n");
+}
+
+Kvm::~Kvm()
+{
+    close(kvmFD);
+}
+
+Kvm *
+Kvm::create()
+{
+    if (!instance)
+        instance = new Kvm();
+
+    return instance;
+}
+
+bool
+Kvm::capUserMemory() const
+{
+    return checkExtension(KVM_CAP_USER_MEMORY) != 0;
+}
+
+bool
+Kvm::capSetTSSAddress() const
+{
+    return checkExtension(KVM_CAP_SET_TSS_ADDR) != 0;
+}
+
+bool
+Kvm::capExtendedCPUID() const
+{
+    return checkExtension(KVM_CAP_EXT_CPUID) != 0;
+}
+
+bool
+Kvm::capUserNMI() const
+{
+#ifdef KVM_CAP_USER_NMI
+    return checkExtension(KVM_CAP_USER_NMI) != 0;
+#else
+    return false;
+#endif
+}
+
+int
+Kvm::capCoalescedMMIO() const
+{
+    return checkExtension(KVM_CAP_COALESCED_MMIO);
+}
+
+bool
+Kvm::capOneReg() const
+{
+#ifdef KVM_CAP_ONE_REG
+    return checkExtension(KVM_CAP_ONE_REG) != 0;
+#else
+    return false;
+#endif
+}
+
+bool
+Kvm::capIRQChip() const
+{
+    return checkExtension(KVM_CAP_IRQCHIP) != 0;
+}
+
+bool
+Kvm::getSupportedCPUID(struct kvm_cpuid2 &cpuid) const
+{
+#if defined(__i386__) || defined(__x86_64__)
+    if (ioctl(KVM_GET_SUPPORTED_CPUID, (void *)&cpuid) == -1) {
+        if (errno == E2BIG)
+            return false;
+        else
+            panic("KVM: Failed to get supported CPUID (errno: %i)\n", errno);
+    } else
+        return true;
+#else
+    panic("KVM: getSupportedCPUID is unsupported on this platform.\n");
+#endif
+}
+
+int
+Kvm::checkExtension(int extension) const
+{
+    int ret = ioctl(KVM_CHECK_EXTENSION, extension);
+    if (ret == -1)
+        panic("KVM: ioctl failed when checking for extension\n");
+    return ret;
+}
+
+int
+Kvm::ioctl(int request, long p1) const
+{
+    assert(kvmFD != -1);
+
+    return ::ioctl(kvmFD, request, p1);
+}
+
+int
+Kvm::createVM()
+{
+    int vmFD;
+
+    vmFD = ioctl(KVM_CREATE_VM);
+    if (vmFD == -1)
+        panic("Failed to create KVM VM\n");
+
+    return vmFD;
+}
+
+
+KvmVM::KvmVM(KvmVMParams *params)
+    : SimObject(params),
+      kvm(), system(params->system),
+      vmFD(kvm.createVM()),
+      started(false),
+      nextVCPUID(0)
+{
+    /* Setup the coalesced MMIO regions */
+    for (int i = 0; i < params->coalescedMMIO.size(); ++i)
+        coalesceMMIO(params->coalescedMMIO[i]);
+}
+
+KvmVM::~KvmVM()
+{
+    close(vmFD);
+}
+
+void
+KvmVM::cpuStartup()
+{
+    if (started)
+        return;
+    started = true;
+
+    delayedStartup();
+}
+
+void
+KvmVM::delayedStartup()
+{
+    const std::vector<std::pair<AddrRange, uint8_t*> >&memories(
+        system->getPhysMem().getBackingStore());
+
+    DPRINTF(Kvm, "Mapping %i memory region(s)\n", memories.size());
+    for (int slot(0); slot < memories.size(); ++slot) {
+        const AddrRange &range(memories[slot].first);
+        void *pmem(memories[slot].second);
+
+        if (pmem) {
+            DPRINTF(Kvm, "Mapping region: 0x%p -> 0x%llx [size: 0x%llx]\n",
+                    pmem, range.start(), range.size());
+
+            setUserMemoryRegion(slot, pmem, range, 0 /* flags */);
+        } else {
+            DPRINTF(Kvm, "Zero-region not mapped: [0x%llx]\n", range.start());
+            hack("KVM: Zero memory handled as IO\n");
+        }
+    }
+}
+
+void
+KvmVM::setUserMemoryRegion(uint32_t slot,
+                           void *host_addr, AddrRange guest_range,
+                           uint32_t flags)
+{
+    if (guest_range.interleaved())
+        panic("Tried to map an interleaved memory range into a KVM VM.\n");
+
+    setUserMemoryRegion(slot, host_addr,
+                        guest_range.start(), guest_range.size(),
+                        flags);
+}
+
+void
+KvmVM::setUserMemoryRegion(uint32_t slot,
+                           void *host_addr, Addr guest_addr,
+                           uint64_t len, uint32_t flags)
+{
+    struct kvm_userspace_memory_region m;
+
+    memset(&m, 0, sizeof(m));
+    m.slot = slot;
+    m.flags = flags;
+    m.guest_phys_addr = (uint64_t)guest_addr;
+    m.memory_size = len;
+    m.userspace_addr = (__u64)host_addr;
+
+    if (ioctl(KVM_SET_USER_MEMORY_REGION, (void *)&m) == -1) {
+        panic("Failed to setup KVM memory region:\n"
+              "\tHost Address: 0x%p\n"
+              "\tGuest Address: 0x%llx\n",
+              "\tSize: %ll\n",
+              "\tFlags: 0x%x\n",
+              m.userspace_addr, m.guest_phys_addr,
+              m.memory_size, m.flags);
+    }
+}
+
+void
+KvmVM::coalesceMMIO(const AddrRange &range)
+{
+    coalesceMMIO(range.start(), range.size());
+}
+
+void
+KvmVM::coalesceMMIO(Addr start, int size)
+{
+    struct kvm_coalesced_mmio_zone zone;
+
+    zone.addr = start;
+    zone.size = size;
+    zone.pad = 0;
+
+    DPRINTF(Kvm, "KVM: Registering coalesced MMIO region [0x%x, 0x%x]\n",
+            zone.addr, zone.addr + zone.size - 1);
+    if (ioctl(KVM_REGISTER_COALESCED_MMIO, (void *)&zone) == -1)
+        panic("KVM: Failed to register coalesced MMIO region (%i)\n",
+              errno);
+}
+
+void
+KvmVM::setTSSAddress(Addr tss_address)
+{
+    if (ioctl(KVM_SET_TSS_ADDR, (unsigned long)tss_address) == -1)
+        panic("KVM: Failed to set VM TSS address\n");
+}
+
+void
+KvmVM::createIRQChip()
+{
+    if (_hasKernelIRQChip)
+        panic("KvmVM::createIRQChip called twice.\n");
+
+    if (ioctl(KVM_CREATE_IRQCHIP) != -1) {
+        _hasKernelIRQChip = true;
+    } else {
+        warn("KVM: Failed to create in-kernel IRQ chip (errno: %i)\n",
+             errno);
+        _hasKernelIRQChip = false;
+    }
+}
+
+void
+KvmVM::setIRQLine(uint32_t irq, bool high)
+{
+    struct kvm_irq_level kvm_level;
+
+    kvm_level.irq = irq;
+    kvm_level.level = high ? 1 : 0;
+
+    if (ioctl(KVM_IRQ_LINE, &kvm_level) == -1)
+        panic("KVM: Failed to set IRQ line level (errno: %i)\n",
+              errno);
+}
+
+int
+KvmVM::createVCPU(long vcpuID)
+{
+    int fd;
+
+    fd = ioctl(KVM_CREATE_VCPU, vcpuID);
+    if (fd == -1)
+        panic("KVM: Failed to create virtual CPU");
+
+    return fd;
+}
+
+long
+KvmVM::allocVCPUID()
+{
+    return nextVCPUID++;
+}
+
+int
+KvmVM::ioctl(int request, long p1) const
+{
+    assert(vmFD != -1);
+
+    return ::ioctl(vmFD, request, p1);
+}
+
+
+KvmVM *
+KvmVMParams::create()
+{
+    static bool created = false;
+    if (created)
+        warn_once("Use of multiple KvmVMs is currently untested!\n");
+
+    created = true;
+
+    return new KvmVM(this);
+}