From 1da4e2f4fbd99f3fbf4275fc89617ffd671af95d Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 19 May 2017 16:26:16 +1000 Subject: KVM: PPC: Book3S HV: Don't let VCPU sleep if it has a doorbell pending It is possible, through a narrow race condition, for a VCPU to exit the guest with a H_CEDE hypercall while it has a doorbell interrupt pending. In this case, the H_CEDE should return immediately, but in fact it puts the VCPU to sleep until some other interrupt becomes pending or a prod is received (via another VCPU doing H_PROD). This fixes it by checking the DPDES (Directed Privileged Doorbell Exception Status) bit for the thread along with the other interrupt pending bits. Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) (limited to 'arch/powerpc/kvm/book3s_hv.c') diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index ffbb1b359748..36fe8a5d6a44 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -675,6 +675,17 @@ static void kvmppc_create_dtl_entry(struct kvm_vcpu *vcpu, vcpu->arch.dtl.dirty = true; } +/* See if there is a doorbell interrupt pending for a vcpu */ +static bool kvmppc_doorbell_pending(struct kvm_vcpu *vcpu) +{ + int thr; + struct kvmppc_vcore *vc; + + vc = vcpu->arch.vcore; + thr = vcpu->vcpu_id - vc->first_vcpuid; + return !!(vc->dpdes & (1 << thr)); +} + static bool kvmppc_power8_compatible(struct kvm_vcpu *vcpu) { if (vcpu->arch.vcore->arch_compat >= PVR_ARCH_207) @@ -2672,6 +2683,15 @@ static void shrink_halt_poll_ns(struct kvmppc_vcore *vc) vc->halt_poll_ns /= halt_poll_ns_shrink; } +static bool kvmppc_vcpu_woken(struct kvm_vcpu *vcpu) +{ + if (vcpu->arch.pending_exceptions || vcpu->arch.prodded || + kvmppc_doorbell_pending(vcpu)) + return true; + + return false; +} + /* * Check to see if any of the runnable vcpus on the vcore have pending * exceptions or are no longer ceded @@ -2682,8 +2702,7 @@ static int kvmppc_vcore_check_block(struct kvmppc_vcore *vc) int i; for_each_runnable_thread(i, vcpu, vc) { - if (vcpu->arch.pending_exceptions || !vcpu->arch.ceded || - vcpu->arch.prodded) + if (!vcpu->arch.ceded || kvmppc_vcpu_woken(vcpu)) return 1; } @@ -2869,7 +2888,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) break; n_ceded = 0; for_each_runnable_thread(i, v, vc) { - if (!v->arch.pending_exceptions && !v->arch.prodded) + if (!kvmppc_vcpu_woken(v)) n_ceded += v->arch.ceded; else v->arch.ceded = 0; -- cgit