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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 760C0C433B4 for ; Thu, 20 May 2021 12:07:10 +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 00D606105A for ; Thu, 20 May 2021 12:07:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 00D606105A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43222 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ljhSH-0004kX-24 for qemu-devel@archiver.kernel.org; Thu, 20 May 2021 08:07:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56070) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ljhRI-0003yD-Mq for qemu-devel@nongnu.org; Thu, 20 May 2021 08:06:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:56438) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ljhRD-0005EI-JJ for qemu-devel@nongnu.org; Thu, 20 May 2021 08:06:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 07E1661059; Thu, 20 May 2021 12:05:58 +0000 (UTC) Date: Thu, 20 May 2021 13:05:56 +0100 From: Catalin Marinas To: Steven Price Subject: Re: [PATCH v12 7/8] KVM: arm64: ioctl to fetch/store tags in a guest Message-ID: <20210520120556.GC12251@arm.com> References: <20210517123239.8025-1-steven.price@arm.com> <20210517123239.8025-8-steven.price@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210517123239.8025-8-steven.price@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Received-SPF: pass client-ip=198.145.29.99; envelope-from=cmarinas@kernel.org; helo=mail.kernel.org X-Spam_score_int: -66 X-Spam_score: -6.7 X-Spam_bar: ------ X-Spam_report: (-6.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_HI=-5, 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, Marc Zyngier , 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 Mon, May 17, 2021 at 01:32:38PM +0100, Steven Price wrote: > 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]; I forgot the past discussions, what's the reserved for? Future expansion? > 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; > + > + 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); Do we need to check if PG_mte_tagged is set? If the page was not faulted into the guest address space but the VMM has the page, does the gfn_to_pfn_prot() guarantee that a kvm_set_spte_gfn() was called? If not, this may read stale tags. > + } else { > + num_tags = mte_copy_tags_from_user(maddr, tags, > + num_tags); > + kvm_release_pfn_dirty(pfn); > + } Same question here, if the we can't guarantee the stage 2 pte being set, we'd need to set PG_mte_tagged. > + > + 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; > +} > + -- Catalin