Review Board 2.0.15


kvm: Handle inst events at the current instruction count

Review Request #2838 - Created May 18, 2015 and submitted - Latest diff uploaded

Information
Andreas Sandberg
gem5
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Reviewers
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Changeset 10850:2dca1e24a806
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kvm: Handle inst events at the current instruction count

There are cases (particularly when attaching GDB) when instruction
events are scheduled at the current instruction tick. This used to
trigger an assertion error in kvm. This changeset adds a check for
this condition and forces KVM to do a quick entry that completes any
pending IO operations, but does not execute any new instructions,
before servicing the event. We could check if we need to enter KVM at
all, but forcing a quick entry is makes the code slightly cleaner and
does not hurt correctness (performance is hardly an issue in these
cases).

Extensively tested with kvm and gdb on aarch64. Doesn't fixes the assertion error mentioned in the description.