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 BA9B82E7F0A; Mon, 8 Jun 2026 09:36:22 +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=1780911384; cv=none; b=XmGbZAf5DpWyGTErPE6FvXpr56Shr75MRfZSwu003KPJUB/cz42T7fum67HmJ3jLGll2Ek94N9LNSg1Ws/3Ov6hPgR+PEr/ikMdzKomdDBU4wYn+tN2h0Fnj/W2lRIKJM0pjVOnG6v9cs/0KDlgGXnne2EjR5ffGl3ZHMoSDxAs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780911384; c=relaxed/simple; bh=ptBDlnNoQB7aZGMNpR/K2NrWMUcuiU/2bNd4uG2P9Ds=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CCBeECzrGVmsDk8i54nxCB3FmGEYvd3iRT4bJc3MS0MnK25ffctO1uYDF5kYwzDmNJBpiqe8s60d1Lrn95zjtpOH8ah+4n9U9A2JvCM++2aXMg0VFK5sjWOoULe1yOmmOF72JFr1owtuNDD+Dtogu4xqTzJCwEJKwbVssY5eBn4= 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=B0aOHrMn; 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="B0aOHrMn" 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 364782403; Mon, 8 Jun 2026 02:36:17 -0700 (PDT) Received: from [10.57.28.93] (unknown [10.57.28.93]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D15903F86F; Mon, 8 Jun 2026 02:36:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1780911382; bh=ptBDlnNoQB7aZGMNpR/K2NrWMUcuiU/2bNd4uG2P9Ds=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=B0aOHrMn1wQ+AD09z+YNbPv8pr9VNorpnZTqJwtmXy0P+tLj7cuVkyrJFuQH2Ho7a Aukof9amQe7l9icSEd2yyrwS90+GV17g7rkZYQdIEEkU0rYs83LJ7/xS0op07+C9RC f0ntwypkLUd6sc2M1qkm19hj/WmlJnvrcfArIbIo= Message-ID: <0c71b4b8-ad0b-4a24-9f4a-180b2aaacdb6@arm.com> Date: Mon, 8 Jun 2026 10:36:14 +0100 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v14 26/44] arm64: RMI: Allow populating initial contents To: Gavin Shan , 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 , WeiLin.Chang@arm.com, Lorenzo.Pieralisi2@arm.com References: <20260513131757.116630-1-steven.price@arm.com> <20260513131757.116630-27-steven.price@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 28/05/2026 06:30, Gavin Shan wrote: > Hi Steve, > > On 5/13/26 11:17 PM, 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 v13: >>   * Rename realm_create_protected_data_page() to realm_data_map_init(). >> 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             | 106 +++++++++++++++++++++++++++++++ >>   4 files changed, 124 insertions(+) >> >> diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/ >> asm/kvm_rmi.h >> index 007249a13dbc..a2b6bc412a22 100644 >> --- a/arch/arm64/include/asm/kvm_rmi.h >> +++ b/arch/arm64/include/asm/kvm_rmi.h >> @@ -88,6 +88,10 @@ 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 4e16719fda22..d0cd011cf672 100644 >> --- a/arch/arm64/kvm/Kconfig >> +++ b/arch/arm64/kvm/Kconfig >> @@ -38,6 +38,7 @@ 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 ed88a203b892..073ba9181da9 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -2131,6 +2131,19 @@ 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; >> +    } > > s/return ret/return 0; The variable 'ret' can be dropped. kvm_arm_rmi_populate() may return an error though. E.g. if the "reserved" field is set then it's kvm_arm_rmi_populate() that detects that and returns -EINVAL. >>       default: >>           return -EINVAL; >>       } >> diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c >> index a89873a5eb77..209087bcf399 100644 >> --- a/arch/arm64/kvm/rmi.c >> +++ b/arch/arm64/kvm/rmi.c >> @@ -486,6 +486,75 @@ void kvm_realm_unmap_range(struct kvm *kvm, >> unsigned long start, >>           realm_unmap_private_range(kvm, start, end, may_block); >>   } >>   +static int realm_data_map_init(struct kvm *kvm, 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 (rmi_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 == KVM_PGTABLE_LAST_LEVEL, kvm); > >         KVM_BUG_ON(level >= KVM_PGTABLE_LAST_LEVEL, kvm); Ack. >> +        ret = realm_create_rtt_levels(realm, ipa, level, >> +                          KVM_PGTABLE_LAST_LEVEL, NULL); >> +        if (!ret) { >> +            ret = rmi_rtt_data_map_init(rd, dst_phys, ipa, src_phys, >> +                            flags); >> +        } >> +    } >> + >> +    if (ret) { >> +        if (WARN_ON(rmi_undelegate_page(dst_phys))) { >> +            /* Undelegate failed, so we leak the page */ >> +            get_page(pfn_to_page(dst_pfn)); >> +        } >> +    } >> + > >     if (ret && WARN_ON(rmi_undelegate_page(dst_phys)) { >         /* Leak the page that fails to be undelegated */ >         get_page(pfn_to_page(dst_pfn)); >     } Ack >> +    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_data_map_init(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); >> +    ret = kvm_gmem_populate(kvm, base_gfn, u64_to_user_ptr(uaddr), >> pages, >> +                populate_region_cb, &data_flags); >> +    mutex_unlock(&kvm->slots_lock); >> + >> +    return ret; >> +} >> + >>   enum ripas_action { >>       RIPAS_INIT, >>       RIPAS_SET, >> @@ -574,6 +643,43 @@ 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; >> + > > There are more conditions missed here: > >     args->size == 0, return 0; >     args->base + args->size < args->base, return -EINVAL;  // wrapped range Good catch. args->size == 0 can trigger a WARN_ON currently. I'll put the "return 0" after the realm_ensure_created() call so the behaviour matches. I don't think the wrapped range is quite such a problem - but detecting it and rejecting it early seems like a good idea. >> +    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; > > pages_populaged is 'unsigned long', this function returns a 'int' value. pages_populated is *signed* long. This is handling an error code - so if it's negative we expect the error code to be between -1 and -MAX_ERRNO which should easily fit within the 'int' return. For positive values we continue below (encoding the potentially larger number in the args outputs) and return 0. Thanks, Steve >> + >> +    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; > > Thanks, > Gavin >