[PATCH v4 07/11] powerpc/kvm/e500: Applies counting method to monitor lockless pgtbl walks

[Leonardo Bras]

Applies the counting-based method for monitoring lockless pgtable walks on
kvmppc_e500_shadow_map().

Fixes the place where local_irq_restore() is called: previously, if ptep
was NULL, local_irq_restore() would never be called.

Signed-off-by: Leonardo Bras <leonardo at linux.ibm.com>
---
 arch/powerpc/kvm/e500_mmu_host.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 321db0fdb9db..a0be76ad8d14 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -473,6 +473,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 	 * We are holding kvm->mmu_lock so a notifier invalidate
 	 * can't run hence pfn won't change.
 	 */
+	start_lockless_pgtbl_walk(kvm->mm);
 	local_irq_save(flags);
 	ptep = find_linux_pte(pgdir, hva, NULL, NULL);
 	if (ptep) {
@@ -481,15 +482,18 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 		if (pte_present(pte)) {
 			wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) &
 				MAS2_WIMGE_MASK;
-			local_irq_restore(flags);
 		} else {
 			local_irq_restore(flags);
+			end_lockless_pgtbl_walk(kvm->mm);
 			pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n",
 					   __func__, (long)gfn, pfn);
 			ret = -EINVAL;
 			goto out;
 		}
 	}
+	local_irq_restore(flags);
+	end_lockless_pgtbl_walk(kvm->mm);
+
 	kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
 
 	kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
-- 
2.20.1