[Qemu-discuss] Recording I/O activity after KVM does a VMEXIT

[Arnabjyoti Kalita]

Hello all,

I am trying to implement a 'minimal' record-replay mechanism for KVM, which
is similar to the one existing for TCG via -icount. I am trying to record
I/O events only (specifically disk and network events) when KVM does a
VMEXIT. This has led me to the function kvm_cpu_exec where I can clearly
see the different ways of handling all of the possible VMExit cases (like
PIO, MMIO etc.). To record network packets, I am working with the e1000
hardware device.

Can I make sure that all of the network I/O, atleast for the e1000 device
happens through the KVM_EXIT_MMIO case and subsequent use of the
address_space_rw() function ? Do I also need to look at other functions as
well ? Also for recording disk activity, can I make sure that looking out
for the KVM_EXIT_MMIO and/or KVM_EXIT_PIO cases in the vmexit mechanism,
will be enough ?

Let me know if there are other details that I need to take care of. I am
using QEMU 2.11 on a x86-64 CPU and the guest runs a Linux Kernel 4.4 with
Ubuntu 16.04.

Thanks and Regards,
Arnab