[PATCH v20 13/22] 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@xxxxxxxxxxxxxxxx>
Tested-by: Gavin Shan <gshan@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
Changes since v18:
 - Cover pKVM guests for VGIC v3 mandate.
 - Merge the VGIC mandate check in here.
---
 arch/arm64/include/asm/kvm_host.h | 3 +++
 arch/arm64/kvm/mmu.c              | 2 +-
 arch/arm64/kvm/vgic/vgic-init.c   | 2 ++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 871f503e9f164..4d75b8e6797bb 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 */
@@ -1575,6 +1577,7 @@ struct kvm *kvm_arch_alloc_vm(void);
 #define kvm_vm_is_unprotected_pkvm(kvm)		\
 	(is_protected_kvm_enabled() && ((kvm)->arch.vm_flavor == VM_PKVM))
 
+#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 8e092efdf0825..8f21652d3625c 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1252,7 +1252,7 @@ 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