Merge tag 'kvm-ppc-fixes-4.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc

PPC KVM fixes for 4.14

Just one fix here for a host crash that can occur with HV KVM
as a result of resizing the guest hashed page table (HPT).

2 files changed, 29 insertions, 10 deletions

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 7c62967d672c..59247af5fd45 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -646,6 +646,16 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
                 hnow_v = hpte_new_to_old_v(hnow_v, hnow_r);
                 hnow_r = hpte_new_to_old_r(hnow_r);
         }
+
+        /*
+         * If the HPT is being resized, don't update the HPTE,
+         * instead let the guest retry after the resize operation is complete.
+         * The synchronization for hpte_setup_done test vs. set is provided
+         * by the HPTE lock.
+         */
+        if (!kvm->arch.hpte_setup_done)
+                goto out_unlock;
+
         if ((hnow_v & ~HPTE_V_HVLOCK) != hpte[0] || hnow_r != hpte[1] ||
             rev->guest_rpte != hpte[2])
                 /* HPTE has been changed under us; let the guest retry */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 73bf1ebfa78f..8d43cf205d34 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2705,11 +2705,14 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc)
          * Hard-disable interrupts, and check resched flag and signals.
          * If we need to reschedule or deliver a signal, clean up
          * and return without going into the guest(s).
+         * If the hpte_setup_done flag has been cleared, don't go into the
+         * guest because that means a HPT resize operation is in progress.
          */
         local_irq_disable();
         hard_irq_disable();
         if (lazy_irq_pending() || need_resched() ||
-            recheck_signals(&core_info)) {
+            recheck_signals(&core_info) ||
+            (!kvm_is_radix(vc->kvm) && !vc->kvm->arch.hpte_setup_done)) {
                 local_irq_enable();
                 vc->vcore_state = VCORE_INACTIVE;
                 /* Unlock all except the primary vcore */
@@ -3078,7 +3081,7 @@ out:
 
 static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 {
-        int n_ceded, i;
+        int n_ceded, i, r;
         struct kvmppc_vcore *vc;
         struct kvm_vcpu *v;
 
@@ -3132,6 +3135,20 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 
         while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
                !signal_pending(current)) {
+                /* See if the HPT and VRMA are ready to go */
+                if (!kvm_is_radix(vcpu->kvm) &&
+                    !vcpu->kvm->arch.hpte_setup_done) {
+                        spin_unlock(&vc->lock);
+                        r = kvmppc_hv_setup_htab_rma(vcpu);
+                        spin_lock(&vc->lock);
+                        if (r) {
+                                kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY;
+                                kvm_run->fail_entry.hardware_entry_failure_reason = 0;
+                                vcpu->arch.ret = r;
+                                break;
+                        }
+                }
+
                 if (vc->vcore_state == VCORE_PREEMPT && vc->runner == NULL)
                         kvmppc_vcore_end_preempt(vc);
 
@@ -3249,13 +3266,6 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
         /* Order vcpus_running vs. hpte_setup_done, see kvmppc_alloc_reset_hpt */
         smp_mb();
 
-        /* On the first time here, set up HTAB and VRMA */
-        if (!kvm_is_radix(vcpu->kvm) && !vcpu->kvm->arch.hpte_setup_done) {
-                r = kvmppc_hv_setup_htab_rma(vcpu);
-                if (r)
-                        goto out;
-        }
-
         flush_all_to_thread(current);
 
         /* Save userspace EBB and other register values */
@@ -3303,7 +3313,6 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
         }
         mtspr(SPRN_VRSAVE, user_vrsave);
 
- out:
         vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
         atomic_dec(&vcpu->kvm->arch.vcpus_running);
         return r;