[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 <wangyana...@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