mirror of https://gitee.com/openkylin/linux.git
KVM: PPC: Book3S HV: Don't try to signal cpu -1
If the target vcpu for kvmppc_fast_vcpu_kick_hv() is not running on any CPU, then we will have vcpu->arch.thread_cpu == -1, and as it happens, kvmppc_fast_vcpu_kick_hv will call kvmppc_ipi_thread with -1 as the cpu argument. Although this is not meaningful, in the past, before commit1704a81cce
("KVM: PPC: Book3S HV: Use msgsnd for IPIs to other cores on POWER9", 2016-11-18), it was harmless because CPU -1 is not in the same core as any real CPU thread. On a POWER9, however, we don't do the "same core" check, so we were trying to do a msgsnd to thread -1, which is invalid. To avoid this, we add a check to see that vcpu->arch.thread_cpu is >= 0 before calling kvmppc_ipi_thread() with it. Since vcpu->arch.thread_vcpu can change asynchronously, we use READ_ONCE to ensure that the value we check is the same value that we use as the argument to kvmppc_ipi_thread(). Fixes:1704a81cce
("KVM: PPC: Book3S HV: Use msgsnd for IPIs to other cores on POWER9") Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
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@ -182,7 +182,8 @@ static void kvmppc_fast_vcpu_kick_hv(struct kvm_vcpu *vcpu)
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++vcpu->stat.halt_wakeup;
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}
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if (kvmppc_ipi_thread(vcpu->arch.thread_cpu))
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cpu = READ_ONCE(vcpu->arch.thread_cpu);
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if (cpu >= 0 && kvmppc_ipi_thread(cpu))
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return;
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/* CPU points to the first thread of the core */
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