Commit e7c05540 authored by Ricardo Koller's avatar Ricardo Koller Committed by Oliver Upton
Browse files

KVM: arm64: Add helper for creating unlinked stage2 subtrees 



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: default avatarRicardo Koller <ricarkol@google.com>
Reviewed-by: default avatarShaoqin Huang <shahuang@redhat.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20230426172330.1439644-4-ricarkol@google.com


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 02f10845

arch/arm64/include/asm/kvm_pgtable.h

+26 −0
Original line number Diff line number Diff line
@@ -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*().

arch/arm64/kvm/hyp/pgtable.c

+53 −0
Original line number Diff line number Diff line
@@ -1222,6 +1222,59 @@ 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,

	};

	/*

	 * The input address (.addr) is irrelevant for walking an

	 * unlinked table. Construct an ambiguous IA range to map

	 * kvm_granule_size(level) worth of memory.

	 */

	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,