[PATCH v8 21/43] KVM: arm64: Handle realm VCPU load

[Suzuki K Poulose]

On 16/04/2025 14:41, Steven Price wrote:
> When loading a realm VCPU much of the work is handled by the RMM so only
> some of the actions are required. Rearrange kvm_arch_vcpu_load()
> slightly so we can bail out early for a realm guest.
> 
> Signed-off-by: Steven Price <steven.price at arm.com>
> Reviewed-by: Gavin Shan <gshan at redhat.com>
> ---
>   arch/arm64/kvm/arm.c | 13 +++++++++----
>   1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index cf707130ef66..08d5e0d76749 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -644,10 +644,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

I think we use the pkvm hook to skip to the nommu goto, to avoid
the VMID allocation and context flush.


>   	kvm_timer_vcpu_load(vcpu);
>   	kvm_vgic_load(vcpu);
>   	kvm_vcpu_load_debug(vcpu);
> -	if (has_vhe())
> -		kvm_vcpu_load_vhe(vcpu);
> -	kvm_arch_vcpu_load_fp(vcpu);
> -	kvm_vcpu_pmu_restore_guest(vcpu);
>   	if (kvm_arm_is_pvtime_enabled(&vcpu->arch))
>   		kvm_make_request(KVM_REQ_RECORD_STEAL, vcpu);

We could also move thise pvtime to the bottom too ?

>   
> @@ -671,6 +667,15 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>   			     &vcpu->arch.vgic_cpu.vgic_v3);
>   	}
>   
> +	/* No additional state needs to be loaded on Realmed VMs */
> +	if (vcpu_is_rec(vcpu))
> +		return;
> +
> +	if (has_vhe())
> +		kvm_vcpu_load_vhe(vcpu);
> +	kvm_arch_vcpu_load_fp(vcpu);
> +	kvm_vcpu_pmu_restore_guest(vcpu);
> +

With the above addressed:

Reviewed-by: Suzuki K Poulose <suzuki.poulose at arm.com>


>   	if (!cpumask_test_cpu(cpu, vcpu->kvm->arch.supported_cpus))
>   		vcpu_set_on_unsupported_cpu(vcpu);
>   }