The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d28eafc5a64045c78136162af9d4ba42f8230080 Mon Sep 17 00:00:00 2001
From: Paul Mackerras paulus@ozlabs.org Date: Tue, 27 Aug 2019 11:31:37 +1000 Subject: [PATCH] KVM: PPC: Book3S HV: Check for MMU ready on piggybacked virtual cores
When we are running multiple vcores on the same physical core, they could be from different VMs and so it is possible that one of the VMs could have its arch.mmu_ready flag cleared (for example by a concurrent HPT resize) when we go to run it on a physical core. We currently check the arch.mmu_ready flag for the primary vcore but not the flags for the other vcores that will be run alongside it. This adds that check, and also a check when we select the secondary vcores from the preempted vcores list.
Cc: stable@vger.kernel.org # v4.14+ Fixes: 38c53af85306 ("KVM: PPC: Book3S HV: Fix exclusion between HPT resizing and other HPT updates") Signed-off-by: Paul Mackerras paulus@ozlabs.org
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index cde3f5a4b3e4..36d72e9faddf 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2860,7 +2860,7 @@ static void collect_piggybacks(struct core_info *cip, int target_threads) if (!spin_trylock(&pvc->lock)) continue; prepare_threads(pvc); - if (!pvc->n_runnable) { + if (!pvc->n_runnable || !pvc->kvm->arch.mmu_ready) { list_del_init(&pvc->preempt_list); if (pvc->runner == NULL) { pvc->vcore_state = VCORE_INACTIVE; @@ -2881,15 +2881,20 @@ static void collect_piggybacks(struct core_info *cip, int target_threads) spin_unlock(&lp->lock); }
-static bool recheck_signals(struct core_info *cip) +static bool recheck_signals_and_mmu(struct core_info *cip) { int sub, i; struct kvm_vcpu *vcpu; + struct kvmppc_vcore *vc;
- for (sub = 0; sub < cip->n_subcores; ++sub) - for_each_runnable_thread(i, vcpu, cip->vc[sub]) + for (sub = 0; sub < cip->n_subcores; ++sub) { + vc = cip->vc[sub]; + if (!vc->kvm->arch.mmu_ready) + return true; + for_each_runnable_thread(i, vcpu, vc) if (signal_pending(vcpu->arch.run_task)) return true; + } return false; }
@@ -3119,7 +3124,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) local_irq_disable(); hard_irq_disable(); if (lazy_irq_pending() || need_resched() || - recheck_signals(&core_info) || !vc->kvm->arch.mmu_ready) { + recheck_signals_and_mmu(&core_info)) { local_irq_enable(); vc->vcore_state = VCORE_INACTIVE; /* Unlock all except the primary vcore */