On 4/9/23 2:29 PM, Ricardo Koller wrote:
Add a stage2 helper, kvm_pgtable_stage2_create_unlinked(), for
creating unlinked tables (which is the opposite of
kvm_pgtable_stage2_free_unlinked()). Creating an unlinked table is
useful for splitting level 1 and 2 entries into subtrees of PAGE_SIZE
PTEs. For example, a level 1 entry can be split into PAGE_SIZE PTEs
by first creating a fully populated tree, and then use it to replace
the level 1 entry in a single step. This will be used in a subsequent
commit for eager huge-page splitting (a dirty-logging optimization).
Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
Reviewed-by: Shaoqin Huang <shahuang@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_pgtable.h | 26 +++++++++++++++
arch/arm64/kvm/hyp/pgtable.c | 49 ++++++++++++++++++++++++++++
2 files changed, 75 insertions(+)
With the following nits addressed:
Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 3f2d43ba2b628..c8e0e7d9303b2 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -458,6 +458,32 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
*/
void kvm_pgtable_stage2_free_unlinked(struct kvm_pgtable_mm_ops *mm_ops, void *pgtable, u32 level);
+/**
+ * kvm_pgtable_stage2_create_unlinked() - Create an unlinked stage-2 paging structure.
+ * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*().
+ * @phys: Physical address of the memory to map.
+ * @level: Starting 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
^^^^^^^^
Alignment.
+ * page-table pages.
+ * @force_pte: Force mappings to PAGE_SIZE granularity.
+ *
+ * Returns an unlinked page-table tree. This new page-table tree is
+ * not reachable (i.e., it is unlinked) 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: The fully populated (unlinked) stage-2 paging structure, or
+ * an ERR_PTR(error) on failure.
+ */
+kvm_pte_t *kvm_pgtable_stage2_create_unlinked(struct kvm_pgtable *pgt,
+ u64 phys, u32 level,
+ enum kvm_pgtable_prot prot,
+ void *mc, bool force_pte);
+
/**
* 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 633679ee3c49a..477d2be67d401 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1222,6 +1222,55 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
return kvm_pgtable_walk(pgt, addr, size, &walker);
}
+kvm_pte_t *kvm_pgtable_stage2_create_unlinked(struct kvm_pgtable *pgt,
+ u64 phys, u32 level,
+ enum kvm_pgtable_prot prot,
+ void *mc, bool force_pte)
+{
+ struct stage2_map_data map_data = {
+ .phys = phys,
+ .mmu = pgt->mmu,
+ .memcache = mc,
+ .force_pte = force_pte,
+ };
+ struct kvm_pgtable_walker walker = {
+ .cb = stage2_map_walker,
+ .flags = KVM_PGTABLE_WALK_LEAF |
+ KVM_PGTABLE_WALK_SKIP_BBM_TLBI |
+ KVM_PGTABLE_WALK_SKIP_CMO,
+ .arg = &map_data,
+ };
+ /* .addr (the IPA) is irrelevant for an unlinked table */
+ struct kvm_pgtable_walk_data data = {
+ .walker = &walker,
+ .addr = 0,
+ .end = kvm_granule_size(level),
+ };
The comment about '.addr' seems incorrect. The IPA address is still
used to locate the page table entry, so I think it would be something
like below:
/* The IPA address (.addr) is relative to zero */
+ struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
+ kvm_pte_t *pgtable;
+ int ret;
+
+ if (!IS_ALIGNED(phys, kvm_granule_size(level)))
+ return ERR_PTR(-EINVAL);
+
+ ret = stage2_set_prot_attr(pgt, prot, &map_data.attr);
+ if (ret)
+ return ERR_PTR(ret);
+
+ pgtable = mm_ops->zalloc_page(mc);
+ if (!pgtable)
+ return ERR_PTR(-ENOMEM);
+
+ ret = __kvm_pgtable_walk(&data, mm_ops, (kvm_pteref_t)pgtable,
+ level + 1);
+ if (ret) {
+ kvm_pgtable_stage2_free_unlinked(mm_ops, pgtable, level);
+ mm_ops->put_page(pgtable);
+ return ERR_PTR(ret);
+ }
+
+ return pgtable;
+}
int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
struct kvm_pgtable_mm_ops *mm_ops,
Thanks,
Gavin
