Hello Nikos Nikoleris,
I'd like you to do a code review. Please visit
https://gem5-review.googlesource.com/4287
to review the following change.
Change subject: kvm: Add a helper method to access device event queues
......................................................................
kvm: Add a helper method to access device event queues
The VM's event queue is normally used for devices in multi-core KVM
mode. Add a helper method, BaseKvmCPU::deviceEventQueue(), to access
this queue. This makes the intention of code migrating to device event
queues clearer.
Change-Id: Ifb10f553a6d7445c8d562f658cf9d0b1f4c577ff
Signed-off-by: Andreas Sandberg <andreas.sandb...@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikole...@arm.com>
---
M src/cpu/kvm/base.cc
M src/cpu/kvm/base.hh
M src/cpu/kvm/x86_cpu.cc
3 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/src/cpu/kvm/base.cc b/src/cpu/kvm/base.cc
index 6ea99ce..d0f7515 100644
--- a/src/cpu/kvm/base.cc
+++ b/src/cpu/kvm/base.cc
@@ -1147,10 +1147,9 @@
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());
+ // Temporarily lock and migrate to the device event queue to
+ // prevent races in multi-core mode.
+ EventQueue::ScopedMigration migrate(deviceEventQueue());
return dataPort.submitIO(pkt);
}
diff --git a/src/cpu/kvm/base.hh b/src/cpu/kvm/base.hh
index 29872e7..a22637f 100644
--- a/src/cpu/kvm/base.hh
+++ b/src/cpu/kvm/base.hh
@@ -419,6 +419,16 @@
void syncThreadContext();
/**
+ * Get a pointer to the event queue owning devices.
+ *
+ * Devices always live in a separate device event queue when
+ * running in multi-core mode. We need to temporarily migrate to
+ * this queue when accessing devices. By convention, devices and
+ * the VM use the same event queue.
+ */
+ EventQueue *deviceEventQueue() { return vm.eventQueue(); }
+
+ /**
* Update the KVM if the thread context is dirty.
*/
void syncKvmState();
diff --git a/src/cpu/kvm/x86_cpu.cc b/src/cpu/kvm/x86_cpu.cc
index bdbdadf..467e1ba 100644
--- a/src/cpu/kvm/x86_cpu.cc
+++ b/src/cpu/kvm/x86_cpu.cc
@@ -1346,10 +1346,9 @@
}
const MemCmd cmd(isWrite ? MemCmd::WriteReq : MemCmd::ReadReq);
- // 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());
+ // Temporarily lock and migrate to the device event queue to
+ // prevent races in multi-core mode.
+ EventQueue::ScopedMigration migrate(deviceEventQueue());
for (int i = 0; i < count; ++i) {
RequestPtr io_req = new Request(pAddr, kvm_run.io.size,
Request::UNCACHEABLE,
dataMasterId());
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Ifb10f553a6d7445c8d562f658cf9d0b1f4c577ff
Gerrit-Change-Number: 4287
Gerrit-PatchSet: 1
Gerrit-Owner: Andreas Sandberg <andreas.sandb...@arm.com>
Gerrit-Reviewer: Nikos Nikoleris <nikos.nikole...@arm.com>
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