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 X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 840D4C433ED for ; Wed, 19 May 2021 13:52:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50D8E611B0 for ; Wed, 19 May 2021 13:52:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353766AbhESNxZ (ORCPT ); Wed, 19 May 2021 09:53:25 -0400 Received: from foss.arm.com ([217.140.110.172]:40196 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239473AbhESNxY (ORCPT ); Wed, 19 May 2021 09:53:24 -0400 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 9B5BA31B; Wed, 19 May 2021 06:52:04 -0700 (PDT) Received: from [192.168.1.179] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0C3DA3F73B; Wed, 19 May 2021 06:52:01 -0700 (PDT) Subject: Re: [PATCH v12 7/8] KVM: arm64: ioctl to fetch/store tags in a guest To: Marc Zyngier Cc: Catalin Marinas , Will Deacon , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave Martin , Mark Rutland , Thomas Gleixner , qemu-devel@nongnu.org, Juan Quintela , "Dr. David Alan Gilbert" , Richard Henderson , Peter Maydell , Haibo Xu , Andrew Jones References: <20210517123239.8025-1-steven.price@arm.com> <20210517123239.8025-8-steven.price@arm.com> <87sg2ltexj.wl-maz@kernel.org> From: Steven Price Message-ID: <5c0f6cd7-5f2d-de5b-f057-f3b307cb9416@arm.com> Date: Wed, 19 May 2021 14:51:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87sg2ltexj.wl-maz@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/05/2021 19:04, Marc Zyngier wrote: > On Mon, 17 May 2021 13:32:38 +0100, > Steven Price wrote: >> >> The VMM may not wish to have it's own mapping of guest memory mapped >> with PROT_MTE because this causes problems if the VMM has tag checking >> enabled (the guest controls the tags in physical RAM and it's unlikely >> the tags are correct for the VMM). >> >> Instead add a new ioctl which allows the VMM to easily read/write the >> tags from guest memory, allowing the VMM's mapping to be non-PROT_MTE >> while the VMM can still read/write the tags for the purpose of >> migration. >> >> Signed-off-by: Steven Price >> --- >> arch/arm64/include/uapi/asm/kvm.h | 11 +++++ >> arch/arm64/kvm/arm.c | 69 +++++++++++++++++++++++++++++++ >> include/uapi/linux/kvm.h | 1 + >> 3 files changed, 81 insertions(+) >> >> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h >> index 24223adae150..b3edde68bc3e 100644 >> --- a/arch/arm64/include/uapi/asm/kvm.h >> +++ b/arch/arm64/include/uapi/asm/kvm.h >> @@ -184,6 +184,17 @@ struct kvm_vcpu_events { >> __u32 reserved[12]; >> }; >> >> +struct kvm_arm_copy_mte_tags { >> + __u64 guest_ipa; >> + __u64 length; >> + void __user *addr; >> + __u64 flags; >> + __u64 reserved[2]; >> +}; >> + >> +#define KVM_ARM_TAGS_TO_GUEST 0 >> +#define KVM_ARM_TAGS_FROM_GUEST 1 >> + >> /* If you need to interpret the index values, here is the key: */ >> #define KVM_REG_ARM_COPROC_MASK 0x000000000FFF0000 >> #define KVM_REG_ARM_COPROC_SHIFT 16 >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index e89a5e275e25..4b6c83beb75d 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -1309,6 +1309,65 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, >> } >> } >> >> +static int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, >> + struct kvm_arm_copy_mte_tags *copy_tags) >> +{ >> + gpa_t guest_ipa = copy_tags->guest_ipa; >> + size_t length = copy_tags->length; >> + void __user *tags = copy_tags->addr; >> + gpa_t gfn; >> + bool write = !(copy_tags->flags & KVM_ARM_TAGS_FROM_GUEST); >> + int ret = 0; >> + >> + if (copy_tags->reserved[0] || copy_tags->reserved[1]) >> + return -EINVAL; >> + >> + if (copy_tags->flags & ~KVM_ARM_TAGS_FROM_GUEST) >> + return -EINVAL; >> + >> + if (length & ~PAGE_MASK || guest_ipa & ~PAGE_MASK) >> + return -EINVAL; >> + >> + gfn = gpa_to_gfn(guest_ipa); >> + >> + mutex_lock(&kvm->slots_lock); >> + >> + while (length > 0) { >> + kvm_pfn_t pfn = gfn_to_pfn_prot(kvm, gfn, write, NULL); >> + void *maddr; >> + unsigned long num_tags = PAGE_SIZE / MTE_GRANULE_SIZE; > > nit: this is a compile time constant, make it a #define. This will > avoid the confusing overloading of "num_tags" as both an input and an > output for the mte_copy_tags-* functions. No problem, I agree my usage of num_tags wasn't very clear. >> + >> + if (is_error_noslot_pfn(pfn)) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + maddr = page_address(pfn_to_page(pfn)); >> + >> + if (!write) { >> + num_tags = mte_copy_tags_to_user(tags, maddr, num_tags); >> + kvm_release_pfn_clean(pfn); >> + } else { >> + num_tags = mte_copy_tags_from_user(maddr, tags, >> + num_tags); >> + kvm_release_pfn_dirty(pfn); >> + } >> + >> + if (num_tags != PAGE_SIZE / MTE_GRANULE_SIZE) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + gfn++; >> + tags += num_tags; >> + length -= PAGE_SIZE; >> + } >> + >> +out: >> + mutex_unlock(&kvm->slots_lock); >> + return ret; >> +} >> + > > nit again: I'd really prefer it if you moved this to guest.c, where we > already have a bunch of the save/restore stuff. Sure - I'll move it across. Thanks, Steve 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 X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4AA0C433ED for ; Wed, 19 May 2021 13:54:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 51F2C6100C for ; Wed, 19 May 2021 13:54:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 51F2C6100C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; 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Wed, 19 May 2021 06:52:01 -0700 (PDT) Subject: Re: [PATCH v12 7/8] KVM: arm64: ioctl to fetch/store tags in a guest To: Marc Zyngier References: <20210517123239.8025-1-steven.price@arm.com> <20210517123239.8025-8-steven.price@arm.com> <87sg2ltexj.wl-maz@kernel.org> From: Steven Price Message-ID: <5c0f6cd7-5f2d-de5b-f057-f3b307cb9416@arm.com> Date: Wed, 19 May 2021 14:51:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87sg2ltexj.wl-maz@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=217.140.110.172; envelope-from=steven.price@arm.com; helo=foss.arm.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Maydell , "Dr. David Alan Gilbert" , Andrew Jones , Haibo Xu , Suzuki K Poulose , qemu-devel@nongnu.org, Catalin Marinas , Juan Quintela , Richard Henderson , linux-kernel@vger.kernel.org, Dave Martin , James Morse , linux-arm-kernel@lists.infradead.org, Thomas Gleixner , Will Deacon , kvmarm@lists.cs.columbia.edu, Julien Thierry Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 17/05/2021 19:04, Marc Zyngier wrote: > On Mon, 17 May 2021 13:32:38 +0100, > Steven Price wrote: >> >> The VMM may not wish to have it's own mapping of guest memory mapped >> with PROT_MTE because this causes problems if the VMM has tag checking >> enabled (the guest controls the tags in physical RAM and it's unlikely >> the tags are correct for the VMM). >> >> Instead add a new ioctl which allows the VMM to easily read/write the >> tags from guest memory, allowing the VMM's mapping to be non-PROT_MTE >> while the VMM can still read/write the tags for the purpose of >> migration. >> >> Signed-off-by: Steven Price >> --- >> arch/arm64/include/uapi/asm/kvm.h | 11 +++++ >> arch/arm64/kvm/arm.c | 69 +++++++++++++++++++++++++++++++ >> include/uapi/linux/kvm.h | 1 + >> 3 files changed, 81 insertions(+) >> >> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h >> index 24223adae150..b3edde68bc3e 100644 >> --- a/arch/arm64/include/uapi/asm/kvm.h >> +++ b/arch/arm64/include/uapi/asm/kvm.h >> @@ -184,6 +184,17 @@ struct kvm_vcpu_events { >> __u32 reserved[12]; >> }; >> >> +struct kvm_arm_copy_mte_tags { >> + __u64 guest_ipa; >> + __u64 length; >> + void __user *addr; >> + __u64 flags; >> + __u64 reserved[2]; >> +}; >> + >> +#define KVM_ARM_TAGS_TO_GUEST 0 >> +#define KVM_ARM_TAGS_FROM_GUEST 1 >> + >> /* If you need to interpret the index values, here is the key: */ >> #define KVM_REG_ARM_COPROC_MASK 0x000000000FFF0000 >> #define KVM_REG_ARM_COPROC_SHIFT 16 >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index e89a5e275e25..4b6c83beb75d 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -1309,6 +1309,65 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, >> } >> } >> >> +static int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, >> + struct kvm_arm_copy_mte_tags *copy_tags) >> +{ >> + gpa_t guest_ipa = copy_tags->guest_ipa; >> + size_t length = copy_tags->length; >> + void __user *tags = copy_tags->addr; >> + gpa_t gfn; >> + bool write = !(copy_tags->flags & KVM_ARM_TAGS_FROM_GUEST); >> + int ret = 0; >> + >> + if (copy_tags->reserved[0] || copy_tags->reserved[1]) >> + return -EINVAL; >> + >> + if (copy_tags->flags & ~KVM_ARM_TAGS_FROM_GUEST) >> + return -EINVAL; >> + >> + if (length & ~PAGE_MASK || guest_ipa & ~PAGE_MASK) >> + return -EINVAL; >> + >> + gfn = gpa_to_gfn(guest_ipa); >> + >> + mutex_lock(&kvm->slots_lock); >> + >> + while (length > 0) { >> + kvm_pfn_t pfn = gfn_to_pfn_prot(kvm, gfn, write, NULL); >> + void *maddr; >> + unsigned long num_tags = PAGE_SIZE / MTE_GRANULE_SIZE; > > nit: this is a compile time constant, make it a #define. This will > avoid the confusing overloading of "num_tags" as both an input and an > output for the mte_copy_tags-* functions. No problem, I agree my usage of num_tags wasn't very clear. >> + >> + if (is_error_noslot_pfn(pfn)) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + maddr = page_address(pfn_to_page(pfn)); >> + >> + if (!write) { >> + num_tags = mte_copy_tags_to_user(tags, maddr, num_tags); >> + kvm_release_pfn_clean(pfn); >> + } else { >> + num_tags = mte_copy_tags_from_user(maddr, tags, >> + num_tags); >> + kvm_release_pfn_dirty(pfn); >> + } >> + >> + if (num_tags != PAGE_SIZE / MTE_GRANULE_SIZE) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + gfn++; >> + tags += num_tags; >> + length -= PAGE_SIZE; >> + } >> + >> +out: >> + mutex_unlock(&kvm->slots_lock); >> + return ret; >> +} >> + > > nit again: I'd really prefer it if you moved this to guest.c, where we > already have a bunch of the save/restore stuff. Sure - I'll move it across. Thanks, Steve 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 X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4FA2C433B4 for ; Wed, 19 May 2021 13:52:14 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 5666A611AE for ; Wed, 19 May 2021 13:52:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5666A611AE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C41DF4B736; 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Wed, 19 May 2021 06:52:04 -0700 (PDT) Received: from [192.168.1.179] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0C3DA3F73B; Wed, 19 May 2021 06:52:01 -0700 (PDT) Subject: Re: [PATCH v12 7/8] KVM: arm64: ioctl to fetch/store tags in a guest To: Marc Zyngier References: <20210517123239.8025-1-steven.price@arm.com> <20210517123239.8025-8-steven.price@arm.com> <87sg2ltexj.wl-maz@kernel.org> From: Steven Price Message-ID: <5c0f6cd7-5f2d-de5b-f057-f3b307cb9416@arm.com> Date: Wed, 19 May 2021 14:51:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87sg2ltexj.wl-maz@kernel.org> Content-Language: en-GB Cc: "Dr. David Alan Gilbert" , qemu-devel@nongnu.org, Catalin Marinas , Juan Quintela , Richard Henderson , linux-kernel@vger.kernel.org, Dave Martin , linux-arm-kernel@lists.infradead.org, Thomas Gleixner , Will Deacon , kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 17/05/2021 19:04, Marc Zyngier wrote: > On Mon, 17 May 2021 13:32:38 +0100, > Steven Price wrote: >> >> The VMM may not wish to have it's own mapping of guest memory mapped >> with PROT_MTE because this causes problems if the VMM has tag checking >> enabled (the guest controls the tags in physical RAM and it's unlikely >> the tags are correct for the VMM). >> >> Instead add a new ioctl which allows the VMM to easily read/write the >> tags from guest memory, allowing the VMM's mapping to be non-PROT_MTE >> while the VMM can still read/write the tags for the purpose of >> migration. >> >> Signed-off-by: Steven Price >> --- >> arch/arm64/include/uapi/asm/kvm.h | 11 +++++ >> arch/arm64/kvm/arm.c | 69 +++++++++++++++++++++++++++++++ >> include/uapi/linux/kvm.h | 1 + >> 3 files changed, 81 insertions(+) >> >> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h >> index 24223adae150..b3edde68bc3e 100644 >> --- a/arch/arm64/include/uapi/asm/kvm.h >> +++ b/arch/arm64/include/uapi/asm/kvm.h >> @@ -184,6 +184,17 @@ struct kvm_vcpu_events { >> __u32 reserved[12]; >> }; >> >> +struct kvm_arm_copy_mte_tags { >> + __u64 guest_ipa; >> + __u64 length; >> + void __user *addr; >> + __u64 flags; >> + __u64 reserved[2]; >> +}; >> + >> +#define KVM_ARM_TAGS_TO_GUEST 0 >> +#define KVM_ARM_TAGS_FROM_GUEST 1 >> + >> /* If you need to interpret the index values, here is the key: */ >> #define KVM_REG_ARM_COPROC_MASK 0x000000000FFF0000 >> #define KVM_REG_ARM_COPROC_SHIFT 16 >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index e89a5e275e25..4b6c83beb75d 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -1309,6 +1309,65 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, >> } >> } >> >> +static int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, >> + struct kvm_arm_copy_mte_tags *copy_tags) >> +{ >> + gpa_t guest_ipa = copy_tags->guest_ipa; >> + size_t length = copy_tags->length; >> + void __user *tags = copy_tags->addr; >> + gpa_t gfn; >> + bool write = !(copy_tags->flags & KVM_ARM_TAGS_FROM_GUEST); >> + int ret = 0; >> + >> + if (copy_tags->reserved[0] || copy_tags->reserved[1]) >> + return -EINVAL; >> + >> + if (copy_tags->flags & ~KVM_ARM_TAGS_FROM_GUEST) >> + return -EINVAL; >> + >> + if (length & ~PAGE_MASK || guest_ipa & ~PAGE_MASK) >> + return -EINVAL; >> + >> + gfn = gpa_to_gfn(guest_ipa); >> + >> + mutex_lock(&kvm->slots_lock); >> + >> + while (length > 0) { >> + kvm_pfn_t pfn = gfn_to_pfn_prot(kvm, gfn, write, NULL); >> + void *maddr; >> + unsigned long num_tags = PAGE_SIZE / MTE_GRANULE_SIZE; > > nit: this is a compile time constant, make it a #define. This will > avoid the confusing overloading of "num_tags" as both an input and an > output for the mte_copy_tags-* functions. No problem, I agree my usage of num_tags wasn't very clear. >> + >> + if (is_error_noslot_pfn(pfn)) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + maddr = page_address(pfn_to_page(pfn)); >> + >> + if (!write) { >> + num_tags = mte_copy_tags_to_user(tags, maddr, num_tags); >> + kvm_release_pfn_clean(pfn); >> + } else { >> + num_tags = mte_copy_tags_from_user(maddr, tags, >> + num_tags); >> + kvm_release_pfn_dirty(pfn); >> + } >> + >> + if (num_tags != PAGE_SIZE / MTE_GRANULE_SIZE) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + gfn++; >> + tags += num_tags; >> + length -= PAGE_SIZE; >> + } >> + >> +out: >> + mutex_unlock(&kvm->slots_lock); >> + return ret; >> +} >> + > > nit again: I'd really prefer it if you moved this to guest.c, where we > already have a bunch of the save/restore stuff. Sure - I'll move it across. Thanks, Steve _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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 X-Spam-Level: X-Spam-Status: No, score=-15.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFF72C433B4 for ; Wed, 19 May 2021 13:54:08 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7EA006108D for ; 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Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1ljMcK-00FVyN-03 for linux-arm-kernel@lists.infradead.org; Wed, 19 May 2021 13:52:09 +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 9B5BA31B; Wed, 19 May 2021 06:52:04 -0700 (PDT) Received: from [192.168.1.179] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0C3DA3F73B; Wed, 19 May 2021 06:52:01 -0700 (PDT) Subject: Re: [PATCH v12 7/8] KVM: arm64: ioctl to fetch/store tags in a guest To: Marc Zyngier Cc: Catalin Marinas , Will Deacon , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave Martin , Mark Rutland , Thomas Gleixner , qemu-devel@nongnu.org, Juan Quintela , "Dr. David Alan Gilbert" , Richard Henderson , Peter Maydell , Haibo Xu , Andrew Jones References: <20210517123239.8025-1-steven.price@arm.com> <20210517123239.8025-8-steven.price@arm.com> <87sg2ltexj.wl-maz@kernel.org> From: Steven Price Message-ID: <5c0f6cd7-5f2d-de5b-f057-f3b307cb9416@arm.com> Date: Wed, 19 May 2021 14:51:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87sg2ltexj.wl-maz@kernel.org> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210519_065208_165301_E10EFFC9 X-CRM114-Status: GOOD ( 26.38 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 17/05/2021 19:04, Marc Zyngier wrote: > On Mon, 17 May 2021 13:32:38 +0100, > Steven Price wrote: >> >> The VMM may not wish to have it's own mapping of guest memory mapped >> with PROT_MTE because this causes problems if the VMM has tag checking >> enabled (the guest controls the tags in physical RAM and it's unlikely >> the tags are correct for the VMM). >> >> Instead add a new ioctl which allows the VMM to easily read/write the >> tags from guest memory, allowing the VMM's mapping to be non-PROT_MTE >> while the VMM can still read/write the tags for the purpose of >> migration. >> >> Signed-off-by: Steven Price >> --- >> arch/arm64/include/uapi/asm/kvm.h | 11 +++++ >> arch/arm64/kvm/arm.c | 69 +++++++++++++++++++++++++++++++ >> include/uapi/linux/kvm.h | 1 + >> 3 files changed, 81 insertions(+) >> >> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h >> index 24223adae150..b3edde68bc3e 100644 >> --- a/arch/arm64/include/uapi/asm/kvm.h >> +++ b/arch/arm64/include/uapi/asm/kvm.h >> @@ -184,6 +184,17 @@ struct kvm_vcpu_events { >> __u32 reserved[12]; >> }; >> >> +struct kvm_arm_copy_mte_tags { >> + __u64 guest_ipa; >> + __u64 length; >> + void __user *addr; >> + __u64 flags; >> + __u64 reserved[2]; >> +}; >> + >> +#define KVM_ARM_TAGS_TO_GUEST 0 >> +#define KVM_ARM_TAGS_FROM_GUEST 1 >> + >> /* If you need to interpret the index values, here is the key: */ >> #define KVM_REG_ARM_COPROC_MASK 0x000000000FFF0000 >> #define KVM_REG_ARM_COPROC_SHIFT 16 >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index e89a5e275e25..4b6c83beb75d 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -1309,6 +1309,65 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, >> } >> } >> >> +static int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, >> + struct kvm_arm_copy_mte_tags *copy_tags) >> +{ >> + gpa_t guest_ipa = copy_tags->guest_ipa; >> + size_t length = copy_tags->length; >> + void __user *tags = copy_tags->addr; >> + gpa_t gfn; >> + bool write = !(copy_tags->flags & KVM_ARM_TAGS_FROM_GUEST); >> + int ret = 0; >> + >> + if (copy_tags->reserved[0] || copy_tags->reserved[1]) >> + return -EINVAL; >> + >> + if (copy_tags->flags & ~KVM_ARM_TAGS_FROM_GUEST) >> + return -EINVAL; >> + >> + if (length & ~PAGE_MASK || guest_ipa & ~PAGE_MASK) >> + return -EINVAL; >> + >> + gfn = gpa_to_gfn(guest_ipa); >> + >> + mutex_lock(&kvm->slots_lock); >> + >> + while (length > 0) { >> + kvm_pfn_t pfn = gfn_to_pfn_prot(kvm, gfn, write, NULL); >> + void *maddr; >> + unsigned long num_tags = PAGE_SIZE / MTE_GRANULE_SIZE; > > nit: this is a compile time constant, make it a #define. This will > avoid the confusing overloading of "num_tags" as both an input and an > output for the mte_copy_tags-* functions. No problem, I agree my usage of num_tags wasn't very clear. >> + >> + if (is_error_noslot_pfn(pfn)) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + maddr = page_address(pfn_to_page(pfn)); >> + >> + if (!write) { >> + num_tags = mte_copy_tags_to_user(tags, maddr, num_tags); >> + kvm_release_pfn_clean(pfn); >> + } else { >> + num_tags = mte_copy_tags_from_user(maddr, tags, >> + num_tags); >> + kvm_release_pfn_dirty(pfn); >> + } >> + >> + if (num_tags != PAGE_SIZE / MTE_GRANULE_SIZE) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + gfn++; >> + tags += num_tags; >> + length -= PAGE_SIZE; >> + } >> + >> +out: >> + mutex_unlock(&kvm->slots_lock); >> + return ret; >> +} >> + > > nit again: I'd really prefer it if you moved this to guest.c, where we > already have a bunch of the save/restore stuff. Sure - I'll move it across. Thanks, Steve _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel