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authorAndreas Sandberg <andreas.sandberg@arm.com>2016-03-30 10:52:25 +0100
committerAndreas Sandberg <andreas.sandberg@arm.com>2016-03-30 10:52:25 +0100
commita3efb6bd1d0d83297b5b412badc0b7db98b7be1e (patch)
tree424147084794cefe47a22b53758bfb538d1bc16e /src
parentd4eb354e30171c8c1d65c7158eb05369be6c5e2e (diff)
downloadgem5-a3efb6bd1d0d83297b5b412badc0b7db98b7be1e.tar.xz
kvm: Add an option to force context sync on kvm entry/exit
This changeset adds an option to force the kvm-based CPUs to always synchronize the gem5 thread context representation on entry/exit into the kernel. This is very useful for debugging. Unfortunately, it is also the only way to get reliable register contents when using remote gdb functionality. The long-term solution for the latter would be to implement a kvm-specific thread context. Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Curtis Dunham <curtis.dunham@arm.com> Reviewed-by: Alexandru Dutu <alexandru.dutu@amd.com>
Diffstat (limited to 'src')
-rw-r--r--src/cpu/kvm/BaseKvmCPU.py2
-rw-r--r--src/cpu/kvm/base.cc7
-rw-r--r--src/cpu/kvm/base.hh6
3 files changed, 15 insertions, 0 deletions
diff --git a/src/cpu/kvm/BaseKvmCPU.py b/src/cpu/kvm/BaseKvmCPU.py
index b7c964669..34ab752de 100644
--- a/src/cpu/kvm/BaseKvmCPU.py
+++ b/src/cpu/kvm/BaseKvmCPU.py
@@ -71,6 +71,8 @@ class BaseKvmCPU(BaseCPU):
kvmVM = Param.KvmVM(Parent.any, 'KVM VM (i.e., shared memory domain)')
useCoalescedMMIO = Param.Bool(False, "Use coalesced MMIO (EXPERIMENTAL)")
usePerfOverflow = Param.Bool(False, "Use perf event overflow counters (EXPERIMENTAL)")
+ alwaysSyncTC = Param.Bool(False,
+ "Always sync thread contexts on entry/exit")
hostFreq = Param.Clock("2GHz", "Host clock frequency")
hostFactor = Param.Float(1.0, "Cycle scale factor")
diff --git a/src/cpu/kvm/base.cc b/src/cpu/kvm/base.cc
index ea0f494e3..bf4d68603 100644
--- a/src/cpu/kvm/base.cc
+++ b/src/cpu/kvm/base.cc
@@ -69,6 +69,7 @@ BaseKvmCPU::BaseKvmCPU(BaseKvmCPUParams *params)
_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),
@@ -557,6 +558,9 @@ BaseKvmCPU::tick()
nextInstEvent > ctrInsts ?
curEventQueue()->nextTick() - curTick() : 0);
+ if (alwaysSyncTC)
+ threadContextDirty = true;
+
// We might need to update the KVM state.
syncKvmState();
@@ -588,6 +592,9 @@ BaseKvmCPU::tick()
// 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) {
diff --git a/src/cpu/kvm/base.hh b/src/cpu/kvm/base.hh
index dd27328be..7ff0cab5c 100644
--- a/src/cpu/kvm/base.hh
+++ b/src/cpu/kvm/base.hh
@@ -575,6 +575,12 @@ class BaseKvmCPU : public BaseCPU
KVMCpuPort instPort;
/**
+ * Be conservative and always synchronize the thread context on
+ * KVM entry/exit.
+ */
+ const bool alwaysSyncTC;
+
+ /**
* Is the gem5 context dirty? Set to true to force an update of
* the KVM vCPU state upon the next call to kvmRun().
*/