Re: [PATCH v19 11/20] KVM: arm64: Mandate VGIC v3 for for VMs running on hyp that don't trust the host

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 22/09/2026 23:42, Jonathan Cameron wrote:
> On Sun, 20 Sep 2026 22:28:36 +0100
> Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
> 
>> pKVM and RMM, both do not trust the host. Add a helper to detect the VMs
> 
> Maybe don't mention RMM yet, or make it clear that isn't here in this
> patch.

Ack.

> 
>> that have "distrusting" hyp. Use this for blocking ioremap of vgic-v2 into
>> stage2 and prevent creation of VGIC other than v3.
>>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

Thanks

> 
> Other than minor comments, it feels to me like these first 11
> patches are good cleanup even without the RMM stuff that follows.
> Perhaps can get these upstream faster than the rest?
> 
> Jonathan
> 
>> ---
>> 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 3211543a85b38..bb156a633ab75 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 */
>> @@ -1546,6 +1548,7 @@ 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 cf293d09e940a..413c4b114d75d 100644
>> --- a/arch/arm64/kvm/mmu.c
>> +++ b/arch/arm64/kvm/mmu.c
>> @@ -1251,7 +1251,7 @@ 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:
>>   	 *
>