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hv: Fix vcpu signaling racing problem in lock instruction emulation

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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>
This commit is contained in:
Yifan Liu
2021-08-27 13:59:27 +08:00
committed by wenlingz
parent 3f4ea38158
commit 10963b04d1
3 changed files with 28 additions and 3 deletions
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1
hypervisor/include/arch/x86/asm/guest/virq.h
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@@ -103,6 +103,7 @@ void vcpu_inject_ud(struct acrn_vcpu *vcpu);
*/
void vcpu_inject_ss(struct acrn_vcpu *vcpu);
void vcpu_make_request(struct acrn_vcpu *vcpu, uint16_t eventid);
bool vcpu_try_cancel_request(struct acrn_vcpu *vcpu, uint16_t eventid);
/*
* @pre vcpu != NULL