Hi guys,
I'm trying to record the instruction pointer at the exact time a guest
was delivered an IOAPIC interrupt. Take for example a PS2 keyboard
press. Clearly, when I read IP during the subsequent exit for
IO_INSTRUCTION I'm just recording the IP of io_read in the handler,
and not the IP at actual interrupt delivery.
Maybe I'm missing something fundamental. It doesn't look like exits
for EXTERNAL_INTERRUPT (shouldn't it?) or INTERRUPT_WINDOW correspond
one-to-one with delivery of these PS2 interrupts.
Just setting request_interrupt_window for these IRQs didn't give me an
INTERRUPT_WINDOW for each key. I guess since the guest doesn't usually
have interrupts masked when I press a key means delivery won't wait
for the window.
Could I record during delivery? I figure I could look at the stack
during the IO_INSTRUCTION exit and figure out what instruction was
actually interrupted, but this would be a Linux-specific solution. Any
other ideas? I think even a simple description of how these interrupts
are being delivered to the guest would help me out a lot.
Thanks,
Kurt
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