Re: [PATCH v17 06/20] KVM: arm64: CCA: Add a new mode for supporting Realm guests

[Gavin Shan <gshan@redhat.com>]

Hi Suzuki,

On 9/9/26 2:22 AM, Suzuki K Poulose wrote:
> Add an explicit mode to support Arm CCA guests.
> 
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
>   Documentation/admin-guide/kernel-parameters.txt | 3 +++
>   arch/arm64/include/asm/kvm_host.h               | 1 +
>   arch/arm64/kvm/arm.c                            | 5 +++++
>   3 files changed, 9 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 68647ff4bdd24..1afe3df3b923e 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3256,6 +3256,9 @@ Kernel parameters
>   			nested: VHE-based mode with support for nested
>   				virtualization. Requires at least ARMv8.4
>   				hardware (with FEAT_NV2).
> +			rmm: Support for running confidential guests in Realm
> +			     world using RMM, as defined by Arm Confidential
> +			     Compute Architecture (CCA)
> 

I'm not sure, but 'realm' would be more appropriate name. rmm (Real Management Monitor) is
the term limited to the firmware to me. Besides, we have been using 'realm' broadly in this
series like kvm_vm_is_realm(), kvm_realm_state() and so on.

   
>   			Defaults to VHE/nVHE based on hardware support. Setting
>   			mode to "protected" will disable kexec and hibernation
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index b2e99c5cb1cd3..31ae9d8d8e92f 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -69,6 +69,7 @@ enum kvm_mode {
>   	KVM_MODE_DEFAULT,
>   	KVM_MODE_PROTECTED,
>   	KVM_MODE_NV,
> +	KVM_MODE_RMM,
>   	KVM_MODE_NONE,
>   };
>   #ifdef CONFIG_KVM
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 9af3bbb2f8c24..50f0adfadab38 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -3264,6 +3264,11 @@ static int __init early_kvm_mode_cfg(char *arg)
>   		return 0;
>   	}
>   
> +	if (strcmp(arg, "rmm") == 0 && !WARN_ON(!is_kernel_in_hyp_mode())) {
> +		kvm_mode = KVM_MODE_RMM;
> +		return 0;
> +	}
> +
>   	return -EINVAL;
>   }
>   early_param("kvm-arm.mode", early_kvm_mode_cfg);

Thanks,
Gavin