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 7E276202F71; Thu, 19 Mar 2026 12:47:34 +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=1773924456; cv=none; b=Zn3MIf38TunPeShTYLCcpJ+ZV8pYVV+UuVIOs18LlmM2SBbB7mfJ0CgRFA2Cn7gidpP2NLujjJY603TNWFaUcN1kZomBOJ0eQDWXbSRUIASB4zUm6hLhCA+WJkxipP+kZ8XcqfT2ZvF2jMSJlbxFHBz30t922EbllUOwr8W66xQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773924456; c=relaxed/simple; bh=GH/G0ccTNjt1Y88BQUjQJ0auMvjf45R1jJ/G5o0e7Yw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=COOVY767urume3JVZhgfXMfHxdGUA7pTrJWz4YGt3iN//nkkpuRgqeK7BjX5CTJeVfH+fBoWjAwBrGZ6+jIs88grHpYZ378CUfx7SGjPYV2cJF7EIBePR/CFE2aqe5BRNjeSJ0curcUMMfC8/akD3S1uffyoRF56MvZJRRfX3Ak= 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; 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 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 B7BEB1A25; Thu, 19 Mar 2026 05:47:27 -0700 (PDT) Received: from [10.1.35.24] (e122027.cambridge.arm.com [10.1.35.24]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3A32F3F778; Thu, 19 Mar 2026 05:47:29 -0700 (PDT) Message-ID: <36870a54-63d3-43bd-bc66-945e56b4689d@arm.com> Date: Thu, 19 Mar 2026 12:47:08 +0000 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 07/48] arm64: RMI: Check for RMI support at KVM init To: Suzuki K Poulose , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , 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 , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve References: <20260318155413.793430-1-steven.price@arm.com> <20260318155413.793430-8-steven.price@arm.com> <8fd56e84-821a-47c7-8735-928057a7a653@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: <8fd56e84-821a-47c7-8735-928057a7a653@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 19/03/2026 10:38, Suzuki K Poulose wrote: > On 18/03/2026 15:53, 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. >> >> Signed-off-by: Steven Price >> --- >> Changes since v12: >>   * Drop check for 4k page size. >> Changes since v11: >>   * Reword slightly the comments on the realm states. >> Changes since v10: >>   * kvm_is_realm() no longer has a NULL check. >>   * Rename from "rme" to "rmi" when referring to the RMM interface. >>   * Check for RME (hardware) support before probing for RMI support. >> 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_rmi.h     | 56 +++++++++++++++++++++++++++ >>   arch/arm64/include/asm/virt.h        |  1 + >>   arch/arm64/kernel/cpufeature.c       |  1 + >>   arch/arm64/kvm/Makefile              |  2 +- >>   arch/arm64/kvm/arm.c                 |  5 +++ >>   arch/arm64/kvm/rmi.c                 | 57 ++++++++++++++++++++++++++++ >>   8 files changed, 143 insertions(+), 1 deletion(-) >>   create mode 100644 arch/arm64/include/asm/kvm_rmi.h >>   create mode 100644 arch/arm64/kvm/rmi.c >> >> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/ >> include/asm/kvm_emulate.h >> index 5bf3d7e1d92c..f38b50151ce8 100644 >> --- a/arch/arm64/include/asm/kvm_emulate.h >> +++ b/arch/arm64/include/asm/kvm_emulate.h >> @@ -688,4 +688,22 @@ static inline void vcpu_set_hcrx(struct kvm_vcpu >> *vcpu) >>               vcpu->arch.hcrx_el2 |= HCRX_EL2_EnASR; >>       } >>   } > > > --8>--- > >> + >> +static inline bool kvm_is_realm(struct kvm *kvm) >> +{ >> +    if (static_branch_unlikely(&kvm_rmi_is_available)) >> +        return kvm->arch.is_realm; >> +    return false; >> +} >> + >> +static inline enum realm_state kvm_realm_state(struct kvm *kvm) >> +{ >> +    return READ_ONCE(kvm->arch.realm.state); >> +} >> + >> +static inline bool vcpu_is_rec(struct kvm_vcpu *vcpu) >> +{ >> +    return false; >> +} >> + >>   #endif /* __ARM64_KVM_EMULATE_H__ */ >> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/ >> asm/kvm_host.h >> index 5d5a3bbdb95e..9267a2f2d65b 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -27,6 +27,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include >>     #define __KVM_HAVE_ARCH_INTC_INITIALIZED >> @@ -405,6 +406,9 @@ struct kvm_arch { >>        * the associated pKVM instance in the hypervisor. >>        */ >>       struct kvm_protected_vm pkvm; >> + >> +    bool is_realm; >> +    struct realm realm; >>   }; >>     struct kvm_vcpu_fault_info { >> diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/ >> asm/kvm_rmi.h >> new file mode 100644 >> index 000000000000..3506f50b05cd >> --- /dev/null >> +++ b/arch/arm64/include/asm/kvm_rmi.h >> @@ -0,0 +1,56 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * Copyright (C) 2023-2025 ARM Ltd. >> + */ >> + >> +#ifndef __ASM_KVM_RMI_H >> +#define __ASM_KVM_RMI_H >> + >> +/** >> + * enum realm_state - State of a Realm >> + */ >> +enum realm_state { >> +    /** >> +     * @REALM_STATE_NONE: >> +     *      Realm has not yet been created. rmi_realm_create() has not >> +     *      yet been called. >> +     */ >> +    REALM_STATE_NONE, >> +    /** >> +     * @REALM_STATE_NEW: >> +     *      Realm is under construction, rmi_realm_create() has been >> +     *      called, but it is not yet activated. Pages may be populated. >> +     */ >> +    REALM_STATE_NEW, >> +    /** >> +     * @REALM_STATE_ACTIVE: >> +     *      Realm has been created and is eligible for execution with >> +     *      rmi_rec_enter(). Pages may no longer be populated with >> +     *      rmi_data_create(). >> +     */ >> +    REALM_STATE_ACTIVE, >> +    /** >> +     * @REALM_STATE_DYING: >> +     *      Realm is in the process of being destroyed or has already >> been >> +     *      destroyed. >> +     */ >> +    REALM_STATE_DYING, >> +    /** >> +     * @REALM_STATE_DEAD: >> +     *      Realm has been destroyed. >> +     */ >> +    REALM_STATE_DEAD >> +}; >> + >> +/** >> + * struct realm - Additional per VM data for a Realm >> + * >> + * @state: The lifetime state machine for the realm >> + */ >> +struct realm { >> +    enum realm_state state; >> +}; >> + > > > --8<--- > > Minor nit: The above looks out of place in this patch. Could we > move it to where this may be actually used ? Yes, good point. This can be moved to patch 12 quite easily. I think originally I'd needed this earlier on, but the code's moved on. Thanks, Steve > Rest looks good to me. > > >> +void kvm_init_rmi(void); >> + >> +#endif /* __ASM_KVM_RMI_H */ >> diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/ >> virt.h >> index b51ab6840f9c..dc9b2899e0b2 100644 >> --- a/arch/arm64/include/asm/virt.h >> +++ b/arch/arm64/include/asm/virt.h >> @@ -87,6 +87,7 @@ void __hyp_reset_vectors(void); >>   bool is_kvm_arm_initialised(void); >>     DECLARE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); >> +DECLARE_STATIC_KEY_FALSE(kvm_rmi_is_available); >>     static inline bool is_pkvm_initialized(void) >>   { >> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/ >> cpufeature.c >> index c31f8e17732a..ddf7e57f23e8 100644 >> --- a/arch/arm64/kernel/cpufeature.c >> +++ b/arch/arm64/kernel/cpufeature.c >> @@ -289,6 +289,7 @@ static const struct arm64_ftr_bits >> ftr_id_aa64isar3[] = { >>   static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = { >>       ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, >> ID_AA64PFR0_EL1_CSV3_SHIFT, 4, 0), >>       ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, >> ID_AA64PFR0_EL1_CSV2_SHIFT, 4, 0), >> +    ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, >> ID_AA64PFR0_EL1_RME_SHIFT, 4, 0), >>       ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, >> ID_AA64PFR0_EL1_DIT_SHIFT, 4, 0), >>       ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, >> ID_AA64PFR0_EL1_AMU_SHIFT, 4, 0), >>       ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, >> ID_AA64PFR0_EL1_MPAM_SHIFT, 4, 0), >> diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile >> index 3ebc0570345c..e17c4077d8e7 100644 >> --- a/arch/arm64/kvm/Makefile >> +++ b/arch/arm64/kvm/Makefile >> @@ -16,7 +16,7 @@ CFLAGS_handle_exit.o += -Wno-override-init >>   kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \ >>        inject_fault.o va_layout.o handle_exit.o config.o \ >>        guest.o debug.o reset.o sys_regs.o stacktrace.o \ >> -     vgic-sys-reg-v3.o fpsimd.o pkvm.o \ >> +     vgic-sys-reg-v3.o fpsimd.o pkvm.o rmi.o \ >>        arch_timer.o trng.o vmid.o emulate-nested.o nested.o at.o \ >>        vgic/vgic.o vgic/vgic-init.o \ >>        vgic/vgic-irqfd.o vgic/vgic-v2.o \ >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index 29f0326f7e00..274d7866efdc 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -39,6 +39,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include >>   #include >>   @@ -104,6 +105,8 @@ long kvm_get_cap_for_kvm_ioctl(unsigned int >> ioctl, long *ext) >>       return -EINVAL; >>   } >>   +DEFINE_STATIC_KEY_FALSE(kvm_rmi_is_available); >> + >>   DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector); >>     DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base); >> @@ -2921,6 +2924,8 @@ static __init int kvm_arm_init(void) >>         in_hyp_mode = is_kernel_in_hyp_mode(); >>   +    kvm_init_rmi(); >> + >>       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/rmi.c b/arch/arm64/kvm/rmi.c >> new file mode 100644 >> index 000000000000..fac151580c01 >> --- /dev/null >> +++ b/arch/arm64/kvm/rmi.c >> @@ -0,0 +1,57 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * Copyright (C) 2023-2025 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); >> +    unsigned long aa64pfr0 = >> read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); >> + >> +    /* 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; >> + >> +    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_rmi(void) >> +{ >> +    /* Continue without realm support if we can't agree on a version */ >> +    if (rmi_check_version()) >> +        return; >> + >> +    /* Future patch will enable static branch kvm_rmi_is_available */ >> +} >