[RFC,v1,21/26] KVM: arm64: Mark a protected VM's memory as unmappable at initialization

Commit Message

Fuad Tabba Feb. 22, 2024, 4:10 p.m. UTC

A protected VM's memory is private by default and not mappable by
the host until explicitly shared by the guest. Therefore, start
off with all the memory of a protected guest as NOT_MAPPABLE.

Signed-off-by: Fuad Tabba <[e-mail]>
---
 arch/arm64/kvm/pkvm.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

Patch

diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index bfd4858a7bd1..75247a3ced3d 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -220,13 +220,41 @@  bool pkvm_is_hyp_created(struct kvm *host_kvm)
 	return READ_ONCE(host_kvm->arch.pkvm.handle);
 }
 
+static int pkvm_mark_protected_mem_not_mappable(struct kvm *kvm)
+{
+	struct kvm_memory_slot *memslot;
+	struct kvm_memslots *slots;
+	int bkt, r;
+
+	if (!IS_ENABLED(CONFIG_KVM_GENERIC_PRIVATE_MEM_MAPPABLE))
+		return 0;
+
+	slots = kvm_memslots(kvm);
+	kvm_for_each_memslot(memslot, bkt, slots) {
+		if (!kvm_slot_can_be_private(memslot))
+			continue;
+
+		r = kvm_vm_set_mem_attributes_kernel(kvm,
+			memslot->base_gfn, memslot->base_gfn + memslot->npages,
+			KVM_MEMORY_ATTRIBUTE_NOT_MAPPABLE);
+		if (r)
+			return r;
+	}
+
+	return 0;
+}
+
 int pkvm_create_hyp_vm(struct kvm *host_kvm)
 {
 	int ret = 0;
 
 	mutex_lock(&host_kvm->lock);
-	if (!pkvm_is_hyp_created(host_kvm))
-		ret = __pkvm_create_hyp_vm(host_kvm);
+	if (!pkvm_is_hyp_created(host_kvm)) {
+		if (kvm_vm_is_protected(host_kvm))
+			ret = pkvm_mark_protected_mem_not_mappable(host_kvm);
+		if (!ret)
+			ret = __pkvm_create_hyp_vm(host_kvm);
+	}
 	mutex_unlock(&host_kvm->lock);
 
 	return ret;