mirror of https://gitee.com/openkylin/qemu.git
9a94ee5bb1
When a CPU is stopped with the 'stop-self' RTAS call, its state 'halted' is switched to 1 and, in this case, the MSR is not taken into account anymore in the cpu_has_work() routine. Only the pending hardware interrupts are checked with their LPCR:PECE* enablement bit. If the DECR timer fires after 'stop-self' is called and before the CPU 'stop' state is reached, the nearly-dead CPU will have some work to do and the guest will crash. This case happens very frequently with the not yet upstream P9 XIVE exploitation mode. In XICS mode, the DECR is occasionally fired but after 'stop' state, so no work is to be done and the guest survives. I suspect there is a race between the QEMU mainloop triggering the timers and the TCG CPU thread but I could not quite identify the root cause. To be safe, let's disable in the LPCR all the exceptions which can cause an exit while the CPU is in power-saving mode and reenable them when the CPU is started. Signed-off-by: Cédric Le Goater <clg@kaod.org> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> |
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