[PATCH v14 20/44] arm64: RMI: Support for the VGIC in realms

[Steven Price]

On 28/05/2026 05:07, Gavin Shan wrote:
> Hi Steve,
> 
> On 5/13/26 11:17 PM, Steven Price wrote:
>> The RMM provides emulation of a VGIC to the realm guest. With RMM v2.0
>> the registers are passed in the system registers so this works similar
>> to a normal guest, but kvm_arch_vcpu_put() need reordering to early out,
>> and realm guests don't support GICv2 even if the host does.
>>
>> Signed-off-by: Steven Price <steven.price at arm.com>
>> ---
>> Changes from v12:
>>   * GIC registers are now passed in the system registers rather than via
>>     rec_entry/rec_exit which removes most of the changes.
>> Changes from v11:
>>   * Minor changes to align with the previous patches. Note that the VGIC
>>     handling will change with RMM v2.0.
>> Changes from v10:
>>   * Make sure we sync the VGIC v4 state, and only populate valid lrs from
>>     the list.
>> Changes from v9:
>>   * Copy gicv3_vmcr from the RMM at the same time as gicv3_hcr rather
>>     than having to handle that as a special case.
>> Changes from v8:
>>   * Propagate gicv3_hcr to from the RMM.
>> Changes from v5:
>>   * Handle RMM providing fewer GIC LRs than the hardware supports.
>> ---
>>   arch/arm64/kvm/arm.c            | 11 ++++++++---
>>   arch/arm64/kvm/vgic/vgic-init.c |  2 +-
>>   2 files changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
>> index 93d34762db91..21d9dfdb1ea0 100644
>> --- a/arch/arm64/kvm/arm.c
>> +++ b/arch/arm64/kvm/arm.c
>> @@ -786,19 +786,24 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
>>           kvm_call_hyp_nvhe(__pkvm_vcpu_put);
>>       }
>>   +    kvm_timer_vcpu_put(vcpu);
>> +    kvm_vgic_put(vcpu);
>> +
>> +    vcpu->cpu = -1;
>> +
>> +    if (vcpu_is_rec(vcpu))
>> +        return;
>> +
> 
> For a REC, kvm_vcpu_{load, put}_debug() becomes unbalanced in
> kvm_arch_vcpu_{load, put}().
> kvm_vcpu_load_debug() is called in kvm_arch_vcpu_load(), but
> kvm_vcpu_put_debug() won't
> be called in kvm_arch_vcpu_put() after this whole series is applied.

Good catch. Yes that's not quite right.

Thanks,
Steve

>>       kvm_vcpu_put_debug(vcpu);
>>       kvm_arch_vcpu_put_fp(vcpu);
>>       if (has_vhe())
>>           kvm_vcpu_put_vhe(vcpu);
>> -    kvm_timer_vcpu_put(vcpu);
>> -    kvm_vgic_put(vcpu);
>>       kvm_vcpu_pmu_restore_host(vcpu);
>>       if (vcpu_has_nv(vcpu))
>>           kvm_vcpu_put_hw_mmu(vcpu);
>>       kvm_arm_vmid_clear_active();
>>         vcpu_clear_on_unsupported_cpu(vcpu);
>> -    vcpu->cpu = -1;
>>   }
>>     static void __kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu)
>> diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/
>> vgic-init.c
>> index 933983bb2005..a9db963dfd23 100644
>> --- a/arch/arm64/kvm/vgic/vgic-init.c
>> +++ b/arch/arm64/kvm/vgic/vgic-init.c
>> @@ -81,7 +81,7 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
>>        * the proper checks already.
>>        */
>>       if (type == KVM_DEV_TYPE_ARM_VGIC_V2 &&
>> -        !kvm_vgic_global_state.can_emulate_gicv2)
>> +        (!kvm_vgic_global_state.can_emulate_gicv2 || kvm_is_realm(kvm)))
>>           return -ENODEV;
>>         /*
> 
> Thanks,
> Gavin
>