[PATCH 06/14] KVM: arm64: Return next table from map callbacks

Oliver Upton
2022-08-30T19:42:42Z

The map walkers install new page tables during their traversal. Return
the newly-installed table PTE from the map callbacks to point the walker
at the new table w/o rereading the ptep.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/kvm/hyp/pgtable.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 331f6e3b2c20..f911509e6512 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -202,13 +202,12 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
if (!table && (flags & KVM_PGTABLE_WALK_LEAF)) {
ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, &pte,
KVM_PGTABLE_WALK_LEAF);
- pte = *ptep;
- table = kvm_pte_table(pte, level);
}

if (ret)
goto out;

+ table = kvm_pte_table(pte, level);
if (!table) {
data->addr = ALIGN_DOWN(data->addr, kvm_granule_size(level));
data->addr += kvm_granule_size(level);
@@ -427,6 +426,7 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, kvm_pte
new = kvm_init_table_pte(childp, mm_ops);
mm_ops->get_page(ptep);
smp_store_release(ptep, new);
+ *old = new;

return 0;
}
@@ -768,7 +768,7 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
}

static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
- struct stage2_map_data *data);
+ kvm_pte_t *old, struct stage2_map_data *data);

static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
kvm_pte_t *ptep, kvm_pte_t *old,
@@ -791,7 +791,7 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
*/
kvm_call_hyp(__kvm_tlb_flush_vmid, data->mmu);

- ret = stage2_map_walk_leaf(addr, end, level, ptep, data);
+ ret = stage2_map_walk_leaf(addr, end, level, ptep, old, data);

mm_ops->put_page(ptep);
mm_ops->free_removed_table(childp, level + 1, pgt);
@@ -832,6 +832,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
new = kvm_init_table_pte(childp, mm_ops);
mm_ops->get_page(ptep);
smp_store_release(ptep, new);
+ *old = new;

return 0;
}
--
2.37.2.672.g94769d06f0-goog