Yifan Liu 10963b04d1 hv: Fix vcpu signaling racing problem in lock instruction emulation ... In lock instruction emulation, we use vcpu_make_request and signal_event pairs to shoot down/release other vcpus. However, vcpu_make_request is async and does not guarantee an execution of wait_event on target vcpu, and we want wait_event to be consistent with signal_event. Consider following scenarios: 1, When target vcpu's state has not yet turned to VCPU_RUNNING, vcpu_make_request on ACRN_REQUEST_SPLIT_LOCK does not make sense, and will not result in wait_event. 2, When target vcpu is already requested on ACRN_REQUEST_SPLIT_LOCK (i.e., the corresponding bit in pending_req is set) but not yet handled, the vcpu_make_request call does not result in wait_event as 1 bit is not enough to cache multiple requests. This patch tries to add checks in vcpu_kick_lock_instr_emulation and vcpu_complete_lock_instr_emulation to resolve these issues. Tracked-On: #6502 Signed-off-by: Yifan Liu <yifan1.liu@intel.com> Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>		2021-11-02 15:01:20 +08:00
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x86	hv: Fix vcpu signaling racing problem in lock instruction emulation	2021-11-02 15:01:20 +08:00