[RFC PATCH v1 5/5] KVM: arm64: Adapt page-table code to new handling of coalescing tables

[Yanan Wang]

With new handling of coalescing tables, we can install the block entry
before unmap of the old table mappings. So make the installation in
stage2_map_walk_table_pre(), and elide the installation from function
stage2_map_walk_table_post().

Signed-off-by: Yanan Wang <wangyanan55 at huawei.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index ab1c94985ed0..fb755aac4384 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -436,6 +436,7 @@ struct stage2_map_data {
 	kvm_pte_t			attr;
 
 	kvm_pte_t			*anchor;
+	kvm_pte_t			*follow;
 
 	struct kvm_s2_mmu		*mmu;
 	struct kvm_mmu_memory_cache	*memcache;
@@ -550,13 +551,13 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
 	kvm_set_invalid_pte(ptep);
 
 	/*
-	 * Invalidate the whole stage-2, as we may have numerous leaf
-	 * entries below us which would otherwise need invalidating
-	 * individually.
+	 * If there is an existing table entry and block mapping is needed here,
+	 * then set the anchor and replace it with a block entry. The sub-level
+	 * mappings will later be unmapped lazily.
 	 */
-	kvm_call_hyp(__kvm_tlb_flush_vmid, data->mmu);
 	data->anchor = ptep;
-	return 0;
+	data->follow = kvm_pte_follow(*ptep);
+	return stage2_coalesce_tables_into_block(addr, level, ptep, data);
 }
 
 static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
@@ -608,20 +609,18 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
 				      kvm_pte_t *ptep,
 				      struct stage2_map_data *data)
 {
-	int ret = 0;
-
 	if (!data->anchor)
 		return 0;
 
-	free_page((unsigned long)kvm_pte_follow(*ptep));
-	put_page(virt_to_page(ptep));
-
-	if (data->anchor == ptep) {
+	if (data->anchor != ptep) {
+		free_page((unsigned long)kvm_pte_follow(*ptep));
+		put_page(virt_to_page(ptep));
+	} else {
+		free_page((unsigned long)data->follow);
 		data->anchor = NULL;
-		ret = stage2_map_walk_leaf(addr, end, level, ptep, data);
 	}
 
-	return ret;
+	return 0;
 }
 
 /*
-- 
2.19.1