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(+) 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 + * 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), + }; + 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, -- 2.40.0.577.gac1e443424-goog