From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A8D364DA9CC; Wed, 14 Oct 2026 09:19:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791969553; cv=none; b=Yj5Ncsui0Wx4oCYRiS/ip6evPH406eBjT9SwvnO9nT7uZsiWM0tXOG7uOv7KZgXffBEuoksTxQraNw2Z0Sd4wR6OhoUsWxjs4Fl72TRrID/PV94wifQClRc3kChxAY432D1CgyPHaDcxQzCCgOXSaeFcAdLWTLNCcrOdK7eKS2g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791969553; c=relaxed/simple; bh=0iLcOxtwrgS/UkYKeqlfP2wojjuPV2/CZ+VIyyxdRoM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=q0cjiF7Tp3+cyGe7paERr3fozqyntW6KBbr5PV6jzxvx0p1lwRUItWMVLQwh23im0zMqRkqoGW79OQEZLHfV4bh3r3Zo6Bcw+HYn0af6uUdx0YtnyLXLjJFm4MvKewNfu3I0EFSqubVoDCV5TiqsK4UxnWLap56e0h17F1pQtZc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=M9KEyBoV; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="M9KEyBoV" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B08061596; Wed, 14 Oct 2026 02:19:07 -0700 (PDT) Received: from [10.57.9.28] (unknown [10.57.9.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 81EA83F7B4; Wed, 14 Oct 2026 02:19:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791969551; bh=0iLcOxtwrgS/UkYKeqlfP2wojjuPV2/CZ+VIyyxdRoM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=M9KEyBoVa495mH6cL0uM1F4WPXWVp/YOB8FWlR2edx0LU5TF4kWaBCIBMweLfAu/L B3EWqwjayWkkXs/mZl5eP0M6W1BxPiiNPIlRvo6Y8lIXOm9Vgaktb0RbVWUTPf+fEQ ZAAsndMp4bK76B51zsEP8pnpbn6BOksWzXNx1jLs= Message-ID: <799fb810-c33e-4d0e-9a70-7092c0a681ff@arm.com> Date: Wed, 14 Oct 2026 10:19:05 +0100 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 Content-Language: en-GB To: Gavin Shan , 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> <2586e689-c27d-4e4c-8c69-03e24259cb96@redhat.com> <8be050e3-8af1-4f04-902f-9bc01b209dd0@arm.com> <3fbd4739-a4eb-4428-95ae-ead22e7cf9f2@redhat.com> From: Suzuki K Poulose In-Reply-To: <3fbd4739-a4eb-4428-95ae-ead22e7cf9f2@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 14/10/2026 08:26, Gavin Shan wrote: > On 10/13/26 7:58 PM, Suzuki K Poulose wrote: >> On 13/10/2026 04:53, Gavin Shan wrote: >>> 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) >> >> We could. But I am wondering if that adds any value ? If the RMM >> exists and responds to the RMI_ABI_VERSION, it must be so on a >> platform with v1.2 or greater ? The extra check doesn't hurt. >> > > It's required as documented in section "B1.1 overview" of RMM-spec-v2.0- > bet3. > In the same section, there are more requirements regarding the SMCCC > version > when SVE/SME are supported. I don't see a practical problem if the check is > missed since the combination of TF-A and TF-RMM are the only RMM-spec- > v2.0-bet3 > implementation (as I knew) where the SMCCC version has been set to v1.5 > in the > 'master' branch. Reading the RMM spec again, DFNMZ lists how one can detect if the RMM ABI is present. That specifies that the user checks for SMCCC version >= 1.1, which we do by using arm_smccc_1_1_get_conduit(). Then checking the R{M,S}I_VERSION call is sufficient. So, I think we are good here. Do you agree ? Suzuki > > Thanks, > Gavin > >> Suzuki >> >>>          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; >>>> +} >>>> + >>> >>> [...] >>> >>> >>> >> >