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366223c9f4
As per this kernel documentation:
For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_PAPR, KVM_EXIT_XEN,
KVM_EXIT_EPR, KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR the corresponding
operations are complete (and guest state is consistent) only after userspace
has re-entered the kernel with KVM_RUN. The kernel side will first finish
incomplete operations and then check for pending signals.
The pending state of the operation is not preserved in state which is
visible to userspace, thus userspace should ensure that the operation is
completed before performing a live migration. Userspace can re-enter the
guest with an unmasked signal pending or with the immediate_exit field set
to complete pending operations without allowing any further instructions
to be executed.
Since we capture the state as part of the pause and override it as part
of the resume we must ensure the state is consistent otherwise we will
lose the results of the MMIO or PIO operation that caused the exit from
which we paused.
Fixes: #3658
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
(cherry picked from commit
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