[PATCH v3 19/36] KVM: arm64: Avoid pointless annotation when mapping host-owned pages

Will Deacon
2026-03-05T14:45:16Z

When a page is transitioned to host ownership, we can eagerly map it
into the host stage-2 page-table rather than going via the convoluted
step of a faulting annotation to trigger the mapping.

Call host_stage2_idmap_locked() directly when transitioning a page to
be owned by the host.

Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 28 +++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 0dc1d6fc546c..f673ebe7c888 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -551,23 +551,27 @@ static void __host_update_page_state(phys_addr_t addr, u64 size, enum pkvm_page_

int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
{
- int ret;
+ int ret = -EINVAL;

if (!range_is_memory(addr, addr + size))
return -EPERM;

- ret = host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
- addr, size, &host_s2_pool, owner_id);
- if (ret)
- return ret;
+ switch (owner_id) {
+ case PKVM_ID_HOST:
+ ret = host_stage2_idmap_locked(addr, size, PKVM_HOST_MEM_PROT);
+ if (!ret)
+ __host_update_page_state(addr, size, PKVM_PAGE_OWNED);
+ break;
+ case PKVM_ID_GUEST:
+ case PKVM_ID_HYP:
+ ret = host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
+ addr, size, &host_s2_pool, owner_id);
+ if (!ret)
+ __host_update_page_state(addr, size, PKVM_NOPAGE);
+ break;
+ }

- /* Don't forget to update the vmemmap tracking for the host */
- if (owner_id == PKVM_ID_HOST)
- __host_update_page_state(addr, size, PKVM_PAGE_OWNED);
- else
- __host_update_page_state(addr, size, PKVM_NOPAGE);
-
- return 0;
+ return ret;
}

static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
--
2.53.0.473.g4a7958ca14-goog