Subject: [PATCH v4 08/38] KVM: arm64: Ignore MMU notifier callbacks for protected VMs

From: Will Deacon <[email-masked]>
Date: Fri, 27 Mar 2026 14:00:07 +0000

In preparation for supporting the donation of pinned pages to protected
VMs, return early from the MMU notifiers when called for a protected VM,
as the necessary hypercalls are exposed only for non-protected guests.

Reviewed-by: Fuad Tabba <[email-masked]>
Tested-by: Fuad Tabba <[email-masked]>
Tested-by: Mostafa Saleh <[email-masked]>
Signed-off-by: Will Deacon <[email-masked]>
---
 arch/arm64/kvm/mmu.c  |  9 ++++++---
 arch/arm64/kvm/pkvm.c | 19 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 17d64a1e11e5..5e7821fe0fc4 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -340,6 +340,9 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64
 void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
 			    u64 size, bool may_block)
 {
+	if (kvm_vm_is_protected(kvm_s2_mmu_to_kvm(mmu)))
+		return;
+
 	__unmap_stage2_range(mmu, start, size, may_block);
 }
 
@@ -2223,7 +2226,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 
 bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	if (!kvm->arch.mmu.pgt)
+	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
 		return false;
 
 	__unmap_stage2_range(&kvm->arch.mmu, range->start << PAGE_SHIFT,
@@ -2238,7 +2241,7 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	u64 size = (range->end - range->start) << PAGE_SHIFT;
 
-	if (!kvm->arch.mmu.pgt)
+	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
 		return false;
 
 	return KVM_PGT_FN(kvm_pgtable_stage2_test_clear_young)(kvm->arch.mmu.pgt,
@@ -2254,7 +2257,7 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	u64 size = (range->end - range->start) << PAGE_SHIFT;
 
-	if (!kvm->arch.mmu.pgt)
+	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
 		return false;
 
 	return KVM_PGT_FN(kvm_pgtable_stage2_test_clear_young)(kvm->arch.mmu.pgt,
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index 42f6e50825ac..20d50abb3b94 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -407,7 +407,12 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 
 int pkvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
 {
-	lockdep_assert_held_write(&kvm_s2_mmu_to_kvm(pgt->mmu)->mmu_lock);
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(pgt->mmu);
+
+	if (WARN_ON(kvm_vm_is_protected(kvm)))
+		return -EPERM;
+
+	lockdep_assert_held_write(&kvm->mmu_lock);
 
 	return __pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
 }
@@ -419,6 +424,9 @@ int pkvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
 	struct pkvm_mapping *mapping;
 	int ret = 0;
 
+	if (WARN_ON(kvm_vm_is_protected(kvm)))
+		return -EPERM;
+
 	lockdep_assert_held(&kvm->mmu_lock);
 	for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping) {
 		ret = kvm_call_hyp_nvhe(__pkvm_host_wrprotect_guest, handle, mapping->gfn,
@@ -450,6 +458,9 @@ bool pkvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr, u64
 	struct pkvm_mapping *mapping;
 	bool young = false;
 
+	if (WARN_ON(kvm_vm_is_protected(kvm)))
+		return -EPERM;
+
 	lockdep_assert_held(&kvm->mmu_lock);
 	for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping)
 		young |= kvm_call_hyp_nvhe(__pkvm_host_test_clear_young_guest, handle, mapping->gfn,
@@ -461,12 +472,18 @@ bool pkvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr, u64
 int pkvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr, enum kvm_pgtable_prot prot,
 				    enum kvm_pgtable_walk_flags flags)
 {
+	if (WARN_ON(kvm_vm_is_protected(kvm_s2_mmu_to_kvm(pgt->mmu))))
+		return -EPERM;
+
 	return kvm_call_hyp_nvhe(__pkvm_host_relax_perms_guest, addr >> PAGE_SHIFT, prot);
 }
 
 void pkvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr,
 				 enum kvm_pgtable_walk_flags flags)
 {
+	if (WARN_ON(kvm_vm_is_protected(kvm_s2_mmu_to_kvm(pgt->mmu))))
+		return;
+
 	WARN_ON(kvm_call_hyp_nvhe(__pkvm_host_mkyoung_guest, addr >> PAGE_SHIFT));
 }
 
-- 
2.53.0.1018.g2bb0e51243-goog