linux-kernel - Re: [PATCH v4 43/43] KVM: arm64: Allow activating realms

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Message-ID: <yq5afrqieiyg.fsf@kernel.org>
Date: Mon, 02 Sep 2024 10:43:43 +0530
From: Aneesh Kumar K.V <aneesh.kumar@...nel.org>
To: Steven Price <steven.price@....com>, kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>
Subject: Re: [PATCH v4 43/43] KVM: arm64: Allow activating realms

Steven Price <steven.price@....com> writes:

> Add the ioctl to activate a realm and set the static branch to enable
> access to the realm functionality if the RMM is detected.
>
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>  arch/arm64/kvm/rme.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
> index 9f415411d3b5..1eeef9e15d1c 100644
> --- a/arch/arm64/kvm/rme.c
> +++ b/arch/arm64/kvm/rme.c
> @@ -1194,6 +1194,20 @@ static int kvm_init_ipa_range_realm(struct kvm *kvm,
>  	return realm_init_ipa_state(realm, addr, end);
>  }
>  
> +static int kvm_activate_realm(struct kvm *kvm)
> +{
> +	struct realm *realm = &kvm->arch.realm;
> +
> +	if (kvm_realm_state(kvm) != REALM_STATE_NEW)
> +		return -EINVAL;
> +
> +	if (rmi_realm_activate(virt_to_phys(realm->rd)))
> +		return -ENXIO;
> +
> +	WRITE_ONCE(realm->state, REALM_STATE_ACTIVE);
> +	return 0;
> +}
> +
>  /* Protects access to rme_vmid_bitmap */
>  static DEFINE_SPINLOCK(rme_vmid_lock);
>  static unsigned long *rme_vmid_bitmap;
> @@ -1343,6 +1357,9 @@ int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
>  		r = kvm_populate_realm(kvm, &args);
>  		break;
>  	}
> +	case KVM_CAP_ARM_RME_ACTIVATE_REALM:
> +		r = kvm_activate_realm(kvm);
> +		break;
>  	default:
>  		r = -EINVAL;
>  		break;
> @@ -1599,5 +1616,5 @@ void kvm_init_rme(void)
>  	if (rme_vmid_init())
>  		return;
>  
> -	/* Future patch will enable static branch kvm_rme_is_available */
> +	static_branch_enable(&kvm_rme_is_available);
>

like rsi_present, we might want to use this outside kvm, ex: for TIO.
Can we move this outside module init so that we can have a helper
like is_rme_supported()


-aneesh