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Julien Thierry authored
Currently, the handling a pause signal only sets a state that will be checked at the begining of the CPU run loop. At the checking point the vCPU sends the notification that it is actually paused allowing the pause requester to confirm all vCPUs are paused. Receiving the pause signal during a KVM_RUN ioctl will make KVM exit to userspace. However, there is a small window between that check on cpu->paused and the execution of KVM_RUN where the signal has been received but the vCPU does not go back through the notification and starts KVM_RUN. Since there is no guarantee the vCPU will come back to userspace, the pause requester might deadlock. Perform the pause directly from the signal handler. This relies on a vCPU thread never receiving a pause signal while being pause, but such scenario would have caused a deadlock for the pause requester anyway. Signed-off-by: Julien Thierry <julien.thierry@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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