swig: Fix issue with circular import in 2.0.9/2.0.10

This patch fixes an issue which prevented gem5 from running when built
using swig 2.0.9 and 2.0.10. The generated event.py tried to import
m5.internal which in turn relied on importing event. This patch seems
to fix the problem, and so far has not caused any other issues.
swig: Warn on use of incompatible swig/gcc combinations

This patch removes the fixed swig warning concerning 2.0.9/2.0.10 and
adds a warning message for incompatible combinations of swig and gcc.
mem: Fix scheduling bug in SimpleMemory

This patch ensures that a dequeue event is not scheduled if the memory
controller is waiting for a retry already. Without this check it is
possible for the controller to attempt sending something whilst
already having one packet that is in retry, thus causing the bus to
have an assertion failure.
sim: Fix undefined behavior in the pseudo-inst interface

The order between updating and using arg_num in
PseudoInst::pseudoInst() is currently undefined. This changeset
explicitly updates arg_num after it has been used to extract an
argument.

--HG--
extra : rebase_source : 67c46dc3333d16ce56687ee8aea41ce6c6d133bb
x86: Add support routines to convert between x87 tag formats

This changeset adds the convX87XTagsToTags() and convX87TagsToXTags()
which convert between the tag formats in the FTW register and the
format used in the xsave area. The conversion from to the x87 FTW
representation is currently loses some information since it does not
reconstruct the valid/zero/special flags which are not included in the
xsave representation.
kvm: Fix a case where the run timers weren't armed properly

There is a possibility that the timespec used to arm a timer becomes
zero if the number of ticks used when arming a timer is close to the
resolution of the timer. Due to the semantics of POSIX timers, this
actually disarms the timer. This changeset fixes this issue by
eliminating the rounding error (we always round away from zero
now). It also reuses the minimum number of cycles, which were
previously only used for cycle-based timers, to calculate a more
useful resolution.
kvm: Correctly handle the return value from handleIpr(Read|Write)

The KVM base class incorrectly assumed that handleIprRead and
handleIprWrite both return ticks. This is not the case, instead they
return cycles. This changeset converts the returned cycles to ticks
when handling IPR accesses.
kvm: Initial x86 support

This changeset adds support for KVM on x86. Full support is split
across a number of commits since some features are relatively
complex. This changeset includes support for:

 * Integer state synchronization (including segment regs)
 * CPUID (gem5's CPUID values are inserted into KVM)
 * x86 legacy IO (remapped and handled by gem5's memory system)
 * Memory mapped IO
 * PCI
 * MSRs
 * State dumping

Most of the functionality is fairly straight forward. There are some
quirks to support PCI enumerations since this is done in the TLB(!) in
the simulated CPUs. We currently replicate some of that code.

Unlike the ARM implementation, the x86 implementation of the virtual
CPU does not use the cycles hardware counter. KVM on x86 simulates the
time stamp counter (TSC) in the kernel. If we just measure host cycles
using perfevent, we might end up measuring a slightly different number
of cycles. If we don't get the cycle accounting right, we might end up
rewinding the TSC, with all kinds of chaos as a result.

An additional feature of the KVM CPU on x86 is extended state
dumping. This enables Python scripts controlling the simulator to
request dumping of a subset of the processor state. The following
methods are currenlty supported:

 * dumpFpuRegs
 * dumpIntRegs
 * dumpSpecRegs
 * dumpDebugRegs
 * dumpXCRs
 * dumpXSave
 * dumpVCpuEvents
 * dumpMSRs

Known limitations:
  * M5 ops are currently not supported.
  * FPU synchronization is not supported (only affects CPU switching).

Both of the limitations will be addressed in separate commits.
kvm: Add x86 segment register verification to help debugging
tests: update reference outputs

Apparently only stats.txt was updated the last time, so
this changeset updates other reference output files
(config.ini, simout, simerr, ruby.stats) so that
test output diffs should not be cluttered with irrelevant
changes.  There are a few stats.txt updates too, but
they are in the minority.
kvm: x86: Fix segment registers to make them VMX compatible

There are cases when the segment registers in gem5 are not compatible
with VMX. This changeset works around all known such issues. Specifically:

* The accessed bits in CS, SS, DD, ES, FS, GS are forced to 1.
* The busy bit in TR is forced to 1.
* The protection level of SS is forced to the same protection level as
  CS. The difference /seems/ to be caused by a bug in gem5's x86
  implementation.
x86: Add limited support for extracting function call arguments

Add support for extracting the first 6 64-bit integer argumements to a
function call in X86ISA::getArgument().
ext: Include libfputils

This changeset includes libfputils from revision bbf0d61d75. This
library can be used to convert to and from 80-bit floats and query the
type of an 80-bit float, which is needed to support the x87 FPU.
x86: Add support routines to load and store 80-bit floats

The x87 FPU on x86 supports extended floating point. We currently
handle all floating point on x86 as double and don't support 80-bit
loads/stores. This changeset add a utility function to load and
convert 80-bit floats to doubles (loadFloat80) and another function to
store doubles as 80-bit floats (storeFloat80). Both functions use
libfputils to do the conversion in software. The functions are
currently not used, but are required to handle floating point in KVM
and to properly support all x87 loads/stores.
kvm: FPU synchronization support on x86

This changeset adds support for synchronizing the FPU and SIMD state
of a virtual x86 CPU with gem5. It supports both the XSave API and the
KVM_(GET|SET)_FPU kernel API. The XSave interface can be disabled
using the useXSave parameter (in case of kernel
issues). Unfortunately, KVM_(GET|SET)_FPU interface seems to be buggy
in some kernels (specifically, the MXCSR register isn't always
synchronized), which means that it might not be possible to
synchronize MXCSR on old kernels without the XSave interface.

This changeset depends on the __float80 type in gcc and might not
build using llvm.
config: Add a 'kvm' CPU alias

Add a CPU alias, 'kvm', for the first available KVM-accelerated CPU
model.
kvm: Add support for thread-specific instruction events

Instruction events are currently ignored when executing in KVM. This
changeset adds support for triggering KVM exits based on instruction
counts using hardware performance counters. Depending on the
underlying performance counter implementation, there might be some
inaccuracies due to instructions being counted in the host kernel when
entering/exiting KVM.

Due to limitations/bugs in Linux's performance counter interface, we
can't reliably change the period of an overflow counter. We work
around this issue by detaching and reattaching the counter if we need
to reconfigure it.