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KVM: arm64: Add helper for creating unlinked stage2 subtrees

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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@google.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20230426172330.1439644-4-ricarkol@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Ricardo Koller 2023-04-26 17:23:21 +00:00 committed by Oliver Upton
parent 02f10845f4
commit e7c05540c6
2 changed files with 79 additions and 0 deletions
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26
arch/arm64/include/asm/kvm_pgtable.h
View File

@ -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*().

53
arch/arm64/kvm/hyp/pgtable.c
View File

@ -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,