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[175.34.8.244]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ab38dd5864sm18786368a91.8.2026.10.12.20.53.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Oct 2026 20:53:33 -0700 (PDT) Message-ID: <2586e689-c27d-4e4c-8c69-03e24259cb96@redhat.com> Date: Tue, 13 Oct 2026 13:53:24 +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 v22 02/10] firmware: arm_rmm: Check for RMI support at init To: Suzuki K Poulose , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com, sudeep.holla@arm.com, jonathan.cameron@oss.qualcomm.com References: <20261002061507.1600269-1-suzuki.poulose@arm.com> <20261002061507.1600269-3-suzuki.poulose@arm.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20261002061507.1600269-3-suzuki.poulose@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Suzuki, On 10/2/26 4:14 PM, Suzuki K Poulose wrote: > From: Steven Price > > Query the RMI version number and check if it is a compatible version. > All RMM feature registers are read and exposed for future code to > use. Also restrict the support to SMC conduit. > > We only support this for Little Endian kernels, the Big Endian kernel > support is anyway marked BROKEN and is being removed. > > Cc: Marc Zyngier > Cc: Oliver Upton > Reviewed-by: Jonathan Cameron > Reviewed-by: Gavin Shan > Reviewed-by: Catalin Marinas > Tested-by: Gavin Shan > Signed-off-by: Steven Price > Co-developed-by: Suzuki K Poulose > Signed-off-by: Suzuki K Poulose > --- [...] > --- > MAINTAINERS | 2 + > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/cpufeature.c | 1 + > arch/arm64/kvm/sys_regs.c | 2 + > drivers/firmware/Kconfig | 1 + > drivers/firmware/Makefile | 1 + > drivers/firmware/arm_rmm/Kconfig | 25 +++++++ > drivers/firmware/arm_rmm/Makefile | 1 + > drivers/firmware/arm_rmm/rmi.c | 112 ++++++++++++++++++++++++++++++ > include/linux/arm-rmi-cmds.h | 48 +++++++++++++ > 10 files changed, 194 insertions(+) > create mode 100644 drivers/firmware/arm_rmm/Kconfig > create mode 100644 drivers/firmware/arm_rmm/Makefile > create mode 100644 drivers/firmware/arm_rmm/rmi.c > create mode 100644 include/linux/arm-rmi-cmds.h > [...] > diff --git a/drivers/firmware/arm_rmm/rmi.c b/drivers/firmware/arm_rmm/rmi.c > new file mode 100644 > index 0000000000000..06f5392c982d2 > --- /dev/null > +++ b/drivers/firmware/arm_rmm/rmi.c > @@ -0,0 +1,112 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2023-2026 ARM Ltd. > + */ > + > +#include > +#include > +#include > +#include > + > +#include > +#include > + > +/* RMM v2.0 defines RmiFeatureRegister0 to RmiFeatureRegister4. */ > +static unsigned long rmi_feat_reg_cache[5] __ro_after_init; > + > +static int rmi_check_version(void) > +{ > + unsigned short version_major, version_minor; > + unsigned long host_version = RMI_ABI_VERSION(RMI_ABI_MAJOR_VERSION, > + RMI_ABI_MINOR_VERSION); > + unsigned long aa64pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); > + struct arm_smccc_1_2_regs res = { > + SMC_RMI_VERSION, host_version, > + }; > + > + /* If RME isn't supported, then RMI can't be */ > + if (cpuid_feature_extract_unsigned_field(aa64pfr0, ID_AA64PFR0_EL1_RME_SHIFT) == 0) > + return -ENXIO; > + > + if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_SMC) > + return -ENXIO; I think we need to ensure SMCCC version is v1.2 or a newer one here? arm_smccc_1_2_smc() is immediately called by rmi_smccc_invoke() after this check. if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_SMC || arm_smccc_get_version() < ARM_SMCCC_VERSION_1_2) return -ENXIO; Thanks, Gavin > + > + rmi_smccc_invoke(&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); > + > + pr_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; > + } > + > + pr_info("RMI ABI version %d.%d\n", version_major, version_minor); > + > + return 0; > +} > + [...]