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V" , Emi Kisanuki , Vishal Annapurve , WeiLin.Chang@arm.com, Lorenzo Pieralisi Subject: Re: [PATCH 03/11] KVM: arm64: CCA: Check for RMI support at KVM init Message-ID: References: <20261102141304.126883-1-steven.price@arm.com> <20261102141304.126883-4-steven.price@arm.com> X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20261102141304.126883-4-steven.price@arm.com> Hi Steven, On 11/02 14:12, Steven Price wrote: > Check if the RMI support is sufficient for using in KVM. Specifically, we > will only support creating realm VMs when KVM is set to 'rmm' mode. > > Signed-off-by: Steven Price > --- > arch/arm64/kvm/Kconfig | 1 + > arch/arm64/kvm/rmi.c | 4 +++- > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig > index cecea0820e52..d067063a3686 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -34,6 +34,7 @@ menuconfig KVM > select GUEST_PERF_EVENTS if PERF_EVENTS > select KVM_GUEST_MEMFD > select KVM_GENERIC_PRE_FAULT_MEMORY > + select ARM_RMM_RMI > help > Support hosting virtualized guest machines. > > diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c > index 5ecc8b349869..9d118768550d 100644 > --- a/arch/arm64/kvm/rmi.c > +++ b/arch/arm64/kvm/rmi.c > @@ -3,6 +3,7 @@ > * Copyright (C) 2023-2026 ARM Ltd. > */ > > +#include > #include > > #include > @@ -12,7 +13,8 @@ void kvm_init_rmi(void) > if (kvm_get_mode() != KVM_MODE_RMM) > return; > > - /* TODO: Check if the RMI is available */ > + if (!is_rmi_available()) > + return; >From an admin/operator's perspective, kvm_rmi_is_available would silently remain FALSE in either of the following cases: - kvm-arm.mode=rmm is set, but RMI is not available for some reason. - RMI is available, but the admin forgot to set kvm-arm.mode=rmm. So I think it would be useful to emit diagnostic messages for these cases, for example: if (!is_rmi_available()) { if (kvm_get_mode() == KVM_MODE_RMM) pr_info("Realm VM support is disabled because RMI is not available\n"); return; } if (kvm_get_mode() != KVM_MODE_RMM) { pr_info("Realm VM support is disabled. Use kvm-arm.mode=rmm to enable it\n"); return; } Thanks, Kohei