From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 58A18F459EF for ; Fri, 10 Apr 2026 15:12:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=e5jtY1ViiQf+C79ooKqHog9lVoqX1IC1g6uankYpXiQ=; b=sttGg7I+IZrmIesGRnC9iM2oNu TWupzIhJD6OemtxYcoE3c7F1H7lv5LBTTU6aq7fRzeKVxbTS2/DtwKnbwBM+fSG3E1GwgVkW3mweW 4udaNaKO/9fRLWh04U3Zr6KzN4EsstRPJed+b21e/4q5HWxO9bLqNkxwHuCWcIxL1GcsRCCu8s1FH gn93fPdTCqPqeJ+nP4lVn0SUo6I02wFNAugZUwsnqjUBbGoYEbP1FkWjgOU8EZSctSlnOZ18aQJXb 3SVQ4nQrU6cFFeJQSf5pxw3N0PAnUWWKZYcul3tZj3NkEetTnSylJGHzgONNxkNOIoNZUP+F1ppuF 3nVTNPMg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wBDWq-0000000CQOT-1XCY; Fri, 10 Apr 2026 15:12:16 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wBDWn-0000000CQNW-3K0U for linux-arm-kernel@lists.infradead.org; Fri, 10 Apr 2026 15:12:15 +0000 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 536F01CE2; Fri, 10 Apr 2026 08:12:07 -0700 (PDT) Received: from [10.1.29.18] (e122027.cambridge.arm.com [10.1.29.18]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 25E513FAA1; Fri, 10 Apr 2026 08:12:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1775833933; bh=GJKcHTezPstrZHtfO15ScOCgcXew2OM8/KUMjRAZidQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=QnNDrSZNUzYW/9X57giTRgy3j3izu/JL37kvNQVkk3HfGfFTTYVLTzc+VKrrGKHQ2 sghnshPzg7CRgelAd9jTPw6uhj6OlF4HZVCk1KRFVYcniSC0w9iAMTouf6gXq+b33V siT7P8g5+ChI8QW5j5triYs4S5BA1leyEpwB5Dlc= Message-ID: <04db668a-bb9e-40e4-b974-ba3a6a14bda1@arm.com> Date: Fri, 10 Apr 2026 16:12:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 24/48] arm64: RMI: Allow populating initial contents 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> <20260318155413.793430-25-steven.price@arm.com> <7ab3dcd2-23b9-45a6-84ef-9617c4614c0a@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: <7ab3dcd2-23b9-45a6-84ef-9617c4614c0a@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260410_081213_912188_BEDC608F X-CRM114-Status: GOOD ( 31.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 23/03/2026 11:32, Suzuki K Poulose wrote: > On 18/03/2026 15:53, Steven Price wrote: >> The VMM needs to populate the realm with some data before starting (e.g. >> a kernel and initrd). This is measured by the RMM and used as part of >> the attestation later on. >> >> Signed-off-by: Steven Price >> --- >> Changes since v12: >>   * The ioctl now updates the structure with the amount populated rather >>     than returning this through the ioctl return code. >>   * Use the new RMM v2.0 range based RMI calls. >>   * Adapt to upstream changes in kvm_gmem_populate(). >> Changes since v11: >>   * The multiplex CAP is gone and there's a new ioctl which makes use of >>     the generic kvm_gmem_populate() functionality. >> Changes since v7: >>   * Improve the error codes. >>   * Other minor changes from review. >> Changes since v6: >>   * Handle host potentially having a larger page size than the RMM >>     granule. >>   * Drop historic "par" (protected address range) from >>     populate_par_region() - it doesn't exist within the current >>     architecture. >>   * Add a cond_resched() call in kvm_populate_realm(). >> Changes since v5: >>   * Refactor to use PFNs rather than tracking struct page in >>     realm_create_protected_data_page(). >>   * Pull changes from a later patch (in the v5 series) for accessing >>     pages from a guest memfd. >>   * Do the populate in chunks to avoid holding locks for too long and >>     triggering RCU stall warnings. >> --- >>   arch/arm64/include/asm/kvm_rmi.h |   4 ++ >>   arch/arm64/kvm/Kconfig           |   1 + >>   arch/arm64/kvm/arm.c             |  13 ++++ >>   arch/arm64/kvm/rmi.c             | 111 +++++++++++++++++++++++++++++++ >>   4 files changed, 129 insertions(+) >> >> diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/ >> asm/kvm_rmi.h >> index 46b0cbe6c202..bf663bb240c4 100644 >> --- a/arch/arm64/include/asm/kvm_rmi.h >> +++ b/arch/arm64/include/asm/kvm_rmi.h >> @@ -96,6 +96,10 @@ int kvm_rec_enter(struct kvm_vcpu *vcpu); >>   int kvm_rec_pre_enter(struct kvm_vcpu *vcpu); >>   int handle_rec_exit(struct kvm_vcpu *vcpu, int rec_run_status); >>   +struct kvm_arm_rmi_populate; >> + >> +int kvm_arm_rmi_populate(struct kvm *kvm, >> +             struct kvm_arm_rmi_populate *arg); >>   void kvm_realm_unmap_range(struct kvm *kvm, >>                  unsigned long ipa, >>                  unsigned long size, >> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig >> index 1cac6dfc0972..b495dfd3a8b4 100644 >> --- a/arch/arm64/kvm/Kconfig >> +++ b/arch/arm64/kvm/Kconfig >> @@ -39,6 +39,7 @@ menuconfig KVM >>       select GUEST_PERF_EVENTS if PERF_EVENTS >>       select KVM_GUEST_MEMFD >>       select KVM_GENERIC_MEMORY_ATTRIBUTES >> +    select HAVE_KVM_ARCH_GMEM_POPULATE >>       help >>         Support hosting virtualized guest machines. >>   diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index badb94b398bc..43d05da7e694 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -2089,6 +2089,19 @@ int kvm_arch_vm_ioctl(struct file *filp, >> unsigned int ioctl, unsigned long arg) >>               return -EFAULT; >>           return kvm_vm_ioctl_get_reg_writable_masks(kvm, &range); >>       } >> +    case KVM_ARM_RMI_POPULATE: { >> +        struct kvm_arm_rmi_populate req; >> +        int ret; >> + >> +        if (!kvm_is_realm(kvm)) >> +            return -ENXIO; >> +        if (copy_from_user(&req, argp, sizeof(req))) >> +            return -EFAULT; >> +        ret = kvm_arm_rmi_populate(kvm, &req); >> +        if (copy_to_user(argp, &req, sizeof(req))) >> +            return -EFAULT; >> +        return ret; >> +    } >>       default: >>           return -EINVAL; >>       } >> diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c >> index 13eed6f0b9eb..b48f4e12e4e0 100644 >> --- a/arch/arm64/kvm/rmi.c >> +++ b/arch/arm64/kvm/rmi.c >> @@ -718,6 +718,80 @@ void kvm_realm_unmap_range(struct kvm *kvm, >> unsigned long start, >>           realm_unmap_private_range(kvm, start, end, may_block); >>   } >>   +static int realm_create_protected_data_page(struct kvm *kvm, > > minor nit: To align with the RMM ABI, could we rename this to : > >     realm_data_map_init() ? Makes sense - I have to admit there is a bit of cruft in some of the names because the spec keeps changing ;) >> +                        unsigned long ipa, >> +                        kvm_pfn_t dst_pfn, >> +                        kvm_pfn_t src_pfn, >> +                        unsigned long flags) >> +{ >> +    struct realm *realm = &kvm->arch.realm; >> +    phys_addr_t rd = virt_to_phys(realm->rd); >> +    phys_addr_t dst_phys, src_phys; >> +    int ret; >> + >> +    dst_phys = __pfn_to_phys(dst_pfn); >> +    src_phys = __pfn_to_phys(src_pfn); >> + >> +    if (delegate_page(dst_phys)) >> +        return -ENXIO; >> + >> +    ret = rmi_rtt_data_map_init(rd, dst_phys, ipa, src_phys, flags); >> +    if (RMI_RETURN_STATUS(ret) == RMI_ERROR_RTT) { >> +        /* Create missing RTTs and retry */ >> +        int level = RMI_RETURN_INDEX(ret); >> + >> +        KVM_BUG_ON(level == RMM_RTT_MAX_LEVEL, kvm); > > A buggy VMM can trigger this by calling RMI_POPULATE twice ? Should we > return -ENXIO here rather ? The delegate_page() above could prevent > normal cases, but is the VMM allowed to somehow trigger a "pfn" change > backing the KVM ? Either way, this need not be Fatal ? I believe KVM_BUG_ON is only fatal to the VM - it won't take down the host (KVM_BUG_ON_DATA_CORRUPTION() is for that). AFAICT the delegate_page() check should catch this case, but in the event that it doesn't then this will kill the VM but otherwise recover. Of course if it turns out there is a way of a VMM hitting this we might need to tone down the error handling to something a bit quieter. But I think it would also be good to get an understanding of how this can happen. Thanks, Steve > Otherwise looks good to me. > > Suzuki > > >> + >> +        ret = realm_create_rtt_levels(realm, ipa, level, >> +                          RMM_RTT_MAX_LEVEL, NULL); >> +        if (!ret) { >> +            ret = rmi_rtt_data_map_init(rd, dst_phys, ipa, src_phys, >> +                            flags); >> +        } >> +    } >> + >> +    if (ret) { >> +        if (WARN_ON(undelegate_page(dst_phys))) { >> +            /* Undelegate failed, so we leak the page */ >> +            get_page(pfn_to_page(dst_pfn)); >> +        } >> +    } >> + >> +    return ret; >> +} >> + >> +static int populate_region_cb(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, >> +                  struct page *src_page, void *opaque) >> +{ >> +    unsigned long data_flags = *(unsigned long *)opaque; >> +    phys_addr_t ipa = gfn_to_gpa(gfn); >> + >> +    if (!src_page) >> +        return -EOPNOTSUPP; >> + >> +    return realm_create_protected_data_page(kvm, ipa, pfn, >> +                        page_to_pfn(src_page), >> +                        data_flags); >> +} >> + >> +static long populate_region(struct kvm *kvm, >> +                gfn_t base_gfn, >> +                unsigned long pages, >> +                u64 uaddr, >> +                unsigned long data_flags) >> +{ >> +    long ret = 0; >> + >> +    mutex_lock(&kvm->slots_lock); >> +    mmap_read_lock(current->mm); >> +    ret = kvm_gmem_populate(kvm, base_gfn, u64_to_user_ptr(uaddr), >> pages, >> +                populate_region_cb, &data_flags); >> +    mmap_read_unlock(current->mm); >> +    mutex_unlock(&kvm->slots_lock); >> + >> +    return ret; >> +} >> + >>   enum ripas_action { >>       RIPAS_INIT, >>       RIPAS_SET, >> @@ -815,6 +889,43 @@ static int realm_ensure_created(struct kvm *kvm) >>       return -ENXIO; >>   } >>   +int kvm_arm_rmi_populate(struct kvm *kvm, >> +             struct kvm_arm_rmi_populate *args) >> +{ >> +    unsigned long data_flags = 0; >> +    unsigned long ipa_start = args->base; >> +    unsigned long ipa_end = ipa_start + args->size; >> +    long pages_populated; >> +    int ret; >> + >> +    if (args->reserved || >> +        (args->flags & ~KVM_ARM_RMI_POPULATE_FLAGS_MEASURE) || >> +        !IS_ALIGNED(ipa_start, PAGE_SIZE) || >> +        !IS_ALIGNED(ipa_end, PAGE_SIZE) || >> +        !IS_ALIGNED(args->source_uaddr, PAGE_SIZE)) >> +        return -EINVAL; >> + >> +    ret = realm_ensure_created(kvm); >> +    if (ret) >> +        return ret; >> + >> +    if (args->flags & KVM_ARM_RMI_POPULATE_FLAGS_MEASURE) >> +        data_flags |= RMI_MEASURE_CONTENT; >> + >> +    pages_populated = populate_region(kvm, gpa_to_gfn(ipa_start), >> +                      args->size >> PAGE_SHIFT, >> +                      args->source_uaddr, data_flags); >> + >> +    if (pages_populated < 0) >> +        return pages_populated; >> + >> +    args->size -= pages_populated << PAGE_SHIFT; >> +    args->source_uaddr += pages_populated << PAGE_SHIFT; >> +    args->base += pages_populated << PAGE_SHIFT; >> + >> +    return 0; >> +} >> + >>   static void kvm_complete_ripas_change(struct kvm_vcpu *vcpu) >>   { >>       struct kvm *kvm = vcpu->kvm; >