release/5.2.22/KVM-PPC-Book3S-HV-Check-for-MMU-ready-on-piggybacked.patch

From 8fc1a52264317b1b864ca32cf40e1c10c30e337b 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

commit d28eafc5a64045c78136162af9d4ba42f8230080 upstream.

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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

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 */
-- 
2.7.4