powerpc/mm/thp: Make page table walk safe against thp split/collapse

[deliverable/linux.git] / arch / powerpc / kvm / e500_mmu_host.c

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index a1f5b0d4b1d638c848f9c8dea7ed57a99f0ea91a..4d33e199edcc6769fa94d56a7a0a690a1dd4447c 100644 (file)
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -338,6 +338,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
        pte_t *ptep;
        unsigned int wimg = 0;
        pgd_t *pgdir;
+       unsigned long flags;
 
        /* used to check for invalidations in progress */
        mmu_seq = kvm->mmu_notifier_seq;
@@ -468,14 +469,23 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 
 
        pgdir = vcpu_e500->vcpu.arch.pgdir;
+       /*
+        * We are just looking at the wimg bits, so we don't
+        * care much about the trans splitting bit.
+        * We are holding kvm->mmu_lock so a notifier invalidate
+        * can't run hence pfn won't change.
+        */
+       local_irq_save(flags);
        ptep = find_linux_pte_or_hugepte(pgdir, hva, NULL);
        if (ptep) {
                pte_t pte = READ_ONCE(*ptep);
 
-               if (pte_present(pte))
+               if (pte_present(pte)) {
                        wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) &
                                MAS2_WIMGE_MASK;
-               else {
+                       local_irq_restore(flags);
+               } else {
+                       local_irq_restore(flags);
                        pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n",
                                           __func__, (long)gfn, pfn);
                        ret = -EINVAL;