[PATCH v22 14/23] KVM: arm64: Mandate VGIC v3 for pKVM VMs and Realms

[Suzuki K Poulose]

pKVM does not trust the host. Realm VMs follow a similar trust model, with
the Realm Management Monitor owning the protected state instead of the
host. Add a helper to identify VMs that run under a host-distrusting
hypervisor.

Use this for blocking ioremap of vgic-v2 into stage2 and prevent creation
of VGIC other than v3.

Reviewed-by: Jonathan Cameron <jonathan.cameron at oss.qualcomm.com>
Reviewed-by: Fuad Tabba <fuad.tabba at linux.dev>
Tested-by: Gavin Shan <gshan at redhat.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>
---
 arch/arm64/include/asm/kvm_host.h | 4 ++++
 arch/arm64/kvm/mmu.c              | 2 +-
 arch/arm64/kvm/vgic/vgic-init.c   | 2 ++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 7cb343583953d..56861b75411f1 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -328,6 +328,8 @@ enum fgt_group_id {
 enum kvm_arm_vm_flavor {
 	VM_NVHE,
 	VM_VHE,
+	/* VMs running on a hyp that doesn't trust */
+	MARKER(__VM_DISTRUSTING_HYP),
 	VM_PKVM,		/* Normal guests on pKVM */
 	MARKER(__VM_PROTECTED),
 	VM_PROTECTED_PKVM,	/* Protected VM */
@@ -1562,6 +1564,8 @@ struct kvm *kvm_arch_alloc_vm(void);
 		(__kvm && kvm_vm_is_protected_pkvm(__kvm));		\
 	})
 
+#define kvm_vm_hyp_is_distrusting(kvm)	((kvm)->arch.vm_flavor >= __VM_DISTRUSTING_HYP)
+
 int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature);
 bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
 
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index ccbe2ffeda40b..909ea3f545e83 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1249,7 +1249,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
 				     KVM_PGTABLE_PROT_R |
 				     (writable ? KVM_PGTABLE_PROT_W : 0);
 
-	if (is_protected_kvm_enabled())
+	if (kvm_vm_hyp_is_distrusting(kvm))
 		return -EPERM;
 
 	size += offset_in_page(guest_ipa);
diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 4012df6002ea6..874025513afcc 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -84,6 +84,8 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
 		!kvm_vgic_global_state.can_emulate_gicv2)
 		return -ENODEV;
 
+	if (kvm_vm_hyp_is_distrusting(kvm) && type != KVM_DEV_TYPE_ARM_VGIC_V3)
+		return -ENODEV;
 	/*
 	 * Ensure mutual exclusion with vCPU creation and any vCPU ioctls by:
 	 *
-- 
2.43.0