[PATCH 8/9] KVM: arm64: Stage-2 huge mappings for np-guests

Vincent Donnefort
2025-02-28T10:26:13Z

Now np-guests hypercalls with range are supported, we can let the
hypervisor to install block mappings whenever the Stage-1 allows it,
that is when backed by either Hugetlbfs or THPs. The size of those block
mappings is limited to PMD_SIZE.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 25944d3f8203..271893eff021 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -167,7 +167,7 @@ int kvm_host_prepare_stage2(void *pgt_pool_base)
static bool guest_stage2_force_pte_cb(u64 addr, u64 end,
enum kvm_pgtable_prot prot)
{
- return true;
+ return false;
}

static void *guest_s2_zalloc_pages_exact(size_t size)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 1f55b0c7b11d..3143f3b52c93 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1525,7 +1525,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* logging_active is guaranteed to never be true for VM_PFNMAP
* memslots.
*/
- if (logging_active || is_protected_kvm_enabled()) {
+ if (logging_active) {
force_pte = true;
vma_shift = PAGE_SHIFT;
} else {
@@ -1535,7 +1535,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
switch (vma_shift) {
#ifndef __PAGETABLE_PMD_FOLDED
case PUD_SHIFT:
- if (fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
+ if (is_protected_kvm_enabled() ||
+ fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
break;
fallthrough;
#endif
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index 9c9833f27fe3..b40bcdb1814d 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -342,7 +342,7 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
u64 pfn = phys >> PAGE_SHIFT;
int ret;

- if (size != PAGE_SIZE)
+ if (size != PAGE_SIZE && size != PMD_SIZE)
return -EINVAL;

lockdep_assert_held_write(&kvm->mmu_lock);