Merge tag 'kvm-ppc-fixes-4.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into kvm-master

Third set of PPC KVM fixes for 4.19

One patch here, fixing a potential host crash introduced (or at least
exacerbated) by a previous fix for corruption relating to radix guest
page faults and THP operations.

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 933c574e1cf7..998f8d089ac7 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -646,6 +646,16 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
          */
         local_irq_disable();
         ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
+        /*
+         * If the PTE disappeared temporarily due to a THP
+         * collapse, just return and let the guest try again.
+         */
+        if (!ptep) {
+                local_irq_enable();
+                if (page)
+                        put_page(page);
+                return RESUME_GUEST;
+        }
         pte = *ptep;
         local_irq_enable();