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[175.34.62.5]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7722a269e9csm16651516b3a.17.2025.09.03.04.15.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Sep 2025 04:15:52 -0700 (PDT) Message-ID: <0481109b-769f-464b-aa72-ad6e07bdfa78@redhat.com> Date: Wed, 3 Sep 2025 21:15:43 +1000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 05/43] arm64: RME: Check for RME support at KVM init To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve References: <20250820145606.180644-1-steven.price@arm.com> <20250820145606.180644-6-steven.price@arm.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20250820145606.180644-6-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/21/25 12:55 AM, Steven Price wrote: > Query the RMI version number and check if it is a compatible version. A > static key is also provided to signal that a supported RMM is available. > > Functions are provided to query if a VM or VCPU is a realm (or rec) > which currently will always return false. > > Later patches make use of struct realm and the states as the ioctls > interfaces are added to support realm and REC creation and destruction. > > Reviewed-by: Gavin Shan > Reviewed-by: Suzuki K Poulose > Signed-off-by: Steven Price > --- > Changes since v8: > * No need to guard kvm_init_rme() behind 'in_hyp_mode'. > Changes since v6: > * Improved message for an unsupported RMI ABI version. > Changes since v5: > * Reword "unsupported" message from "host supports" to "we want" to > clarify that 'we' are the 'host'. > Changes since v2: > * Drop return value from kvm_init_rme(), it was always 0. > * Rely on the RMM return value to identify whether the RSI ABI is > compatible. > --- > arch/arm64/include/asm/kvm_emulate.h | 18 +++++++++ > arch/arm64/include/asm/kvm_host.h | 4 ++ > arch/arm64/include/asm/kvm_rme.h | 56 ++++++++++++++++++++++++++++ > arch/arm64/include/asm/virt.h | 1 + > arch/arm64/kvm/Makefile | 2 +- > arch/arm64/kvm/arm.c | 5 +++ > arch/arm64/kvm/rme.c | 56 ++++++++++++++++++++++++++++ > 7 files changed, 141 insertions(+), 1 deletion(-) > create mode 100644 arch/arm64/include/asm/kvm_rme.h > create mode 100644 arch/arm64/kvm/rme.c > [...] > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 888f7c7abf54..76177c56f1ef 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -40,6 +40,7 @@ > #include > #include > #include > +#include > #include > Nit: The header file has been included to and , which has been included to arm.c. So this explicit inclusion can be dropped. > #include > @@ -59,6 +60,8 @@ enum kvm_wfx_trap_policy { > static enum kvm_wfx_trap_policy kvm_wfi_trap_policy __read_mostly = KVM_WFX_NOTRAP_SINGLE_TASK; > static enum kvm_wfx_trap_policy kvm_wfe_trap_policy __read_mostly = KVM_WFX_NOTRAP_SINGLE_TASK; > > +DEFINE_STATIC_KEY_FALSE(kvm_rme_is_available); > + > DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector); > > DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base); > @@ -2836,6 +2839,8 @@ static __init int kvm_arm_init(void) > > in_hyp_mode = is_kernel_in_hyp_mode(); > > + kvm_init_rme(); > + > if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE) || > cpus_have_final_cap(ARM64_WORKAROUND_1508412)) > kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \ > diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c > new file mode 100644 > index 000000000000..67cf2d94cb2d > --- /dev/null > +++ b/arch/arm64/kvm/rme.c > @@ -0,0 +1,56 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2023 ARM Ltd. > + */ > + > +#include > + > +#include > +#include > + > +static int rmi_check_version(void) > +{ > + struct arm_smccc_res res; > + unsigned short version_major, version_minor; > + unsigned long host_version = RMI_ABI_VERSION(RMI_ABI_MAJOR_VERSION, > + RMI_ABI_MINOR_VERSION); > + > + arm_smccc_1_1_invoke(SMC_RMI_VERSION, host_version, &res); > + > + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) > + return -ENXIO; > + > + version_major = RMI_ABI_VERSION_GET_MAJOR(res.a1); > + version_minor = RMI_ABI_VERSION_GET_MINOR(res.a1); > + > + if (res.a0 != RMI_SUCCESS) { > + unsigned short high_version_major, high_version_minor; > + > + high_version_major = RMI_ABI_VERSION_GET_MAJOR(res.a2); > + high_version_minor = RMI_ABI_VERSION_GET_MINOR(res.a2); > + > + kvm_err("Unsupported RMI ABI (v%d.%d - v%d.%d) we want v%d.%d\n", > + version_major, version_minor, > + high_version_major, high_version_minor, > + RMI_ABI_MAJOR_VERSION, > + RMI_ABI_MINOR_VERSION); > + return -ENXIO; > + } > + > + kvm_info("RMI ABI version %d.%d\n", version_major, version_minor); > + > + return 0; > +} > + > +void kvm_init_rme(void) > +{ > + if (PAGE_SIZE != SZ_4K) > + /* Only 4k page size on the host is supported */ > + return; Nit: The comment can be moved before the check, something like below. Otherwise, {} is needed here. /* Only 4kB page size is supported */ if (PAGE_SIZE != SZ_4K) return; > + > + if (rmi_check_version()) > + /* Continue without realm support */ > + return; Nit: same as above. > + > + /* Future patch will enable static branch kvm_rme_is_available */ > +} Thanks, Gavin