Add a stage2 helper, kvm_pgtable_stage2_create_removed(), for creating
removed tables (the opposite of kvm_pgtable_stage2_free_removed()).
Creating a removed table is useful for splitting block PTEs into
subtrees of 4K PTEs. For example, a 1G block PTE can be split into 4K
PTEs by first creating a fully populated tree, and then use it to
replace the 1G PTE in a single step. This will be used in a
subsequent commit for eager huge-page splitting (a dirty-logging
optimization).
No functional change intended. This new function will be used in a
subsequent commit.
Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_pgtable.h | 25 +++++++++++++++
arch/arm64/kvm/hyp/pgtable.c | 47 ++++++++++++++++++++++++++++
2 files changed, 72 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 84a271647007..8ad78d61af7f 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -450,6 +450,31 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
*/
void kvm_pgtable_stage2_free_removed(struct kvm_pgtable_mm_ops *mm_ops, void *pgtable, u32 level);
+/**
+ * kvm_pgtable_stage2_free_removed() - Create a removed stage-2 paging structure.
+ * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*().
+ * @new: Unlinked stage-2 paging structure to be created.
+ * @phys: Physical address of the memory to map.
+ * @level: Level of the stage-2 paging structure to be created.
+ * @prot: Permissions and attributes for the mapping.
+ * @mc: Cache of pre-allocated and zeroed memory from which to allocate
+ * page-table pages.
+ *
+ * Create a removed page-table tree of PAGE_SIZE leaf PTEs under *new.
+ * This new page-table tree is not reachable (i.e., it is removed) from the
+ * root pgd and it's therefore unreachableby the hardware page-table
+ * walker. No TLB invalidation or CMOs are performed.
+ *
+ * If device attributes are not explicitly requested in @prot, then the
+ * mapping will be normal, cacheable.
+ *
+ * Return: 0 only if a fully populated tree was created, negative error
+ * code on failure. No partially-populated table can be returned.
+ */
+int kvm_pgtable_stage2_create_removed(struct kvm_pgtable *pgt,
+ kvm_pte_t *new, u64 phys, u32 level,
+ enum kvm_pgtable_prot prot, void *mc);
+
/**
* kvm_pgtable_stage2_map() - Install a mapping in a guest stage-2 page-table.
* @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*().
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 87fd40d09056..0dee13007776 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1181,6 +1181,53 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
return kvm_pgtable_walk(pgt, addr, size, &walker);
}
+/*
+ * map_data->force_pte is true in order to force creating PAGE_SIZE PTEs.
+ * data->addr is 0 because the IPA is irrelevant for a removed table.
+ */
+int kvm_pgtable_stage2_create_removed(struct kvm_pgtable *pgt,
+ kvm_pte_t *new, u64 phys, u32 level,
+ enum kvm_pgtable_prot prot, void *mc)
+{
+ struct stage2_map_data map_data = {
+ .phys = phys,
+ .mmu = pgt->mmu,
+ .memcache = mc,
+ .force_pte = true,
+ };
+ struct kvm_pgtable_walker walker = {
+ .cb = stage2_map_walker,
+ .flags = KVM_PGTABLE_WALK_LEAF |
+ KVM_PGTABLE_WALK_REMOVED,
+ .arg = &map_data,
+ };
+ struct kvm_pgtable_walk_data data = {
+ .walker = &walker,
+ .addr = 0,
+ .end = kvm_granule_size(level),
+ };
+ struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
+ kvm_pte_t *pgtable;
+ int ret;
+
+ ret = stage2_set_prot_attr(pgt, prot, &map_data.attr);
+ if (ret)
+ return ret;
+
+ pgtable = mm_ops->zalloc_page(mc);
+ if (!pgtable)
+ return -ENOMEM;
+
+ ret = __kvm_pgtable_walk(&data, mm_ops, pgtable, level + 1);
+ if (ret) {
+ kvm_pgtable_stage2_free_removed(mm_ops, pgtable, level);
+ mm_ops->put_page(pgtable);
+ return ret;
+ }
+
+ *new = kvm_init_table_pte(pgtable, mm_ops);
+ return 0;
+}
int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
struct kvm_pgtable_mm_ops *mm_ops,
--
2.39.0.314.g84b9a713c41-goog
