mirror of https://gitee.com/openkylin/linux.git
KVM: PPC: Book3S HV: Call kvmppc_handle_exit_hv() with vcore unlocked
Currently kvmppc_handle_exit_hv() is called with the vcore lock held because it is called within a for_each_runnable_thread loop. However, we already unlock the vcore within kvmppc_handle_exit_hv() under certain circumstances, and this is safe because (a) any vcpus that become runnable and are added to the runnable set by kvmppc_run_vcpu() have their vcpu->arch.trap == 0 and can't actually run in the guest (because the vcore state is VCORE_EXITING), and (b) for_each_runnable_thread is safe against addition or removal of vcpus from the runnable set. Therefore, in order to simplify things for following patches, let's drop the vcore lock in the for_each_runnable_thread loop, so kvmppc_handle_exit_hv() gets called without the vcore lock held. Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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@ -1084,7 +1084,6 @@ static int kvmppc_emulate_doorbell_instr(struct kvm_vcpu *vcpu)
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return RESUME_GUEST;
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}
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/* Called with vcpu->arch.vcore->lock held */
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static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
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struct task_struct *tsk)
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{
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@ -1205,10 +1204,7 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
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swab32(vcpu->arch.emul_inst) :
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vcpu->arch.emul_inst;
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if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) {
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/* Need vcore unlocked to call kvmppc_get_last_inst */
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spin_unlock(&vcpu->arch.vcore->lock);
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r = kvmppc_emulate_debug_inst(run, vcpu);
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spin_lock(&vcpu->arch.vcore->lock);
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} else {
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kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
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r = RESUME_GUEST;
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@ -1224,12 +1220,8 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
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case BOOK3S_INTERRUPT_H_FAC_UNAVAIL:
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r = EMULATE_FAIL;
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if (((vcpu->arch.hfscr >> 56) == FSCR_MSGP_LG) &&
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cpu_has_feature(CPU_FTR_ARCH_300)) {
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/* Need vcore unlocked to call kvmppc_get_last_inst */
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spin_unlock(&vcpu->arch.vcore->lock);
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cpu_has_feature(CPU_FTR_ARCH_300))
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r = kvmppc_emulate_doorbell_instr(vcpu);
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spin_lock(&vcpu->arch.vcore->lock);
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}
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if (r == EMULATE_FAIL) {
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kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
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r = RESUME_GUEST;
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@ -2599,6 +2591,14 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master)
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spin_lock(&vc->lock);
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now = get_tb();
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for_each_runnable_thread(i, vcpu, vc) {
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/*
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* It's safe to unlock the vcore in the loop here, because
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* for_each_runnable_thread() is safe against removal of
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* the vcpu, and the vcore state is VCORE_EXITING here,
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* so any vcpus becoming runnable will have their arch.trap
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* set to zero and can't actually run in the guest.
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*/
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spin_unlock(&vc->lock);
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/* cancel pending dec exception if dec is positive */
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if (now < vcpu->arch.dec_expires &&
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kvmppc_core_pending_dec(vcpu))
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@ -2614,6 +2614,7 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master)
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vcpu->arch.ret = ret;
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vcpu->arch.trap = 0;
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spin_lock(&vc->lock);
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if (is_kvmppc_resume_guest(vcpu->arch.ret)) {
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if (vcpu->arch.pending_exceptions)
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kvmppc_core_prepare_to_enter(vcpu);
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