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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C6696C48BE5 for ; Mon, 21 Jun 2021 09:01:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A69C1611B0 for ; Mon, 21 Jun 2021 09:01:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230225AbhFUJDS (ORCPT ); Mon, 21 Jun 2021 05:03:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:40932 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229618AbhFUJDQ (ORCPT ); Mon, 21 Jun 2021 05:03:16 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8069161002; Mon, 21 Jun 2021 09:01:02 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1lvFng-008omp-Gs; Mon, 21 Jun 2021 10:01:00 +0100 Date: Mon, 21 Jun 2021 10:01:00 +0100 Message-ID: <87a6njd22b.wl-maz@kernel.org> From: Marc Zyngier To: Steven Price 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 , Andrew Jones Subject: Re: [PATCH v16 3/7] KVM: arm64: Introduce MTE VM feature In-Reply-To: <20210618132826.54670-4-steven.price@arm.com> References: <20210618132826.54670-1-steven.price@arm.com> <20210618132826.54670-4-steven.price@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: steven.price@arm.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave.Martin@arm.com, mark.rutland@arm.com, tglx@linutronix.de, qemu-devel@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, richard.henderson@linaro.org, peter.maydell@linaro.org, drjones@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 18 Jun 2021 14:28:22 +0100, Steven Price wrote: > > Add a new VM feature 'KVM_ARM_CAP_MTE' which enables memory tagging > for a VM. This will expose the feature to the guest and automatically > tag memory pages touched by the VM as PG_mte_tagged (and clear the tag > storage) to ensure that the guest cannot see stale tags, and so that > the tags are correctly saved/restored across swap. > > Actually exposing the new capability to user space happens in a later > patch. > > Signed-off-by: Steven Price > --- > arch/arm64/include/asm/kvm_emulate.h | 3 ++ > arch/arm64/include/asm/kvm_host.h | 3 ++ > arch/arm64/kvm/hyp/exception.c | 3 +- > arch/arm64/kvm/mmu.c | 62 +++++++++++++++++++++++++++- > arch/arm64/kvm/sys_regs.c | 7 ++++ > include/uapi/linux/kvm.h | 1 + > 6 files changed, 77 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index f612c090f2e4..6bf776c2399c 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -84,6 +84,9 @@ static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu) > if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) || > vcpu_el1_is_32bit(vcpu)) > vcpu->arch.hcr_el2 |= HCR_TID2; > + > + if (kvm_has_mte(vcpu->kvm)) > + vcpu->arch.hcr_el2 |= HCR_ATA; > } > > static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu) > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 7cd7d5c8c4bc..afaa5333f0e4 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -132,6 +132,8 @@ struct kvm_arch { > > u8 pfr0_csv2; > u8 pfr0_csv3; > + /* Memory Tagging Extension enabled for the guest */ > + bool mte_enabled; > }; > > struct kvm_vcpu_fault_info { > @@ -769,6 +771,7 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu); > #define kvm_arm_vcpu_sve_finalized(vcpu) \ > ((vcpu)->arch.flags & KVM_ARM64_VCPU_SVE_FINALIZED) > > +#define kvm_has_mte(kvm) (system_supports_mte() && (kvm)->arch.mte_enabled) > #define kvm_vcpu_has_pmu(vcpu) \ > (test_bit(KVM_ARM_VCPU_PMU_V3, (vcpu)->arch.features)) > > diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c > index 73629094f903..56426565600c 100644 > --- a/arch/arm64/kvm/hyp/exception.c > +++ b/arch/arm64/kvm/hyp/exception.c > @@ -112,7 +112,8 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, > new |= (old & PSR_C_BIT); > new |= (old & PSR_V_BIT); > > - // TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests) > + if (kvm_has_mte(vcpu->kvm)) > + new |= PSR_TCO_BIT; > > new |= (old & PSR_DIT_BIT); > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index c5d1f3c87dbd..f5305b7561ad 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -822,6 +822,45 @@ transparent_hugepage_adjust(struct kvm_memory_slot *memslot, > return PAGE_SIZE; > } > > +/* > + * The page will be mapped in stage 2 as Normal Cacheable, so the VM will be > + * able to see the page's tags and therefore they must be initialised first. If > + * PG_mte_tagged is set, tags have already been initialised. > + * > + * The race in the test/set of the PG_mte_tagged flag is handled by: > + * - preventing VM_SHARED mappings in a memslot with MTE preventing two VMs > + * racing to santise the same page > + * - mmap_lock protects between a VM faulting a page in and the VMM performing > + * an mprotect() to add VM_MTE > + */ > +static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn, > + unsigned long size) > +{ > + unsigned long i, nr_pages = size >> PAGE_SHIFT; > + struct page *page; > + > + if (!kvm_has_mte(kvm)) > + return 0; > + > + /* > + * pfn_to_online_page() is used to reject ZONE_DEVICE pages > + * that may not support tags. > + */ > + page = pfn_to_online_page(pfn); > + > + if (!page) > + return -EFAULT; > + > + for (i = 0; i < nr_pages; i++, page++) { > + if (!test_bit(PG_mte_tagged, &page->flags)) { > + mte_clear_page_tags(page_address(page)); > + set_bit(PG_mte_tagged, &page->flags); > + } > + } > + > + return 0; > +} > + > static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > struct kvm_memory_slot *memslot, unsigned long hva, > unsigned long fault_status) > @@ -971,8 +1010,16 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (writable) > prot |= KVM_PGTABLE_PROT_W; > > - if (fault_status != FSC_PERM && !device) > + if (fault_status != FSC_PERM && !device) { > + /* Check the VMM hasn't introduced a new VM_SHARED VMA */ > + if (kvm_has_mte(kvm) && vma->vm_flags & VM_SHARED) > + return -EINVAL; nit: I'd rather we return -EFAULT here. That's consistent with other cases where we can't satisfy the mapping. Thanks, M. -- Without deviation from the norm, progress is not possible. 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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C033BC48BE5 for ; Mon, 21 Jun 2021 09:02:40 +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 24D1A6100A for ; Mon, 21 Jun 2021 09:02:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 24D1A6100A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52850 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lvFpG-0007Kv-SF for qemu-devel@archiver.kernel.org; Mon, 21 Jun 2021 05:02:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50794) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lvFnn-0006dU-PX for qemu-devel@nongnu.org; Mon, 21 Jun 2021 05:01:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:57868) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lvFnl-0003Ar-5O for qemu-devel@nongnu.org; Mon, 21 Jun 2021 05:01:07 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8069161002; Mon, 21 Jun 2021 09:01:02 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1lvFng-008omp-Gs; Mon, 21 Jun 2021 10:01:00 +0100 Date: Mon, 21 Jun 2021 10:01:00 +0100 Message-ID: <87a6njd22b.wl-maz@kernel.org> From: Marc Zyngier To: Steven Price Subject: Re: [PATCH v16 3/7] KVM: arm64: Introduce MTE VM feature In-Reply-To: <20210618132826.54670-4-steven.price@arm.com> References: <20210618132826.54670-1-steven.price@arm.com> <20210618132826.54670-4-steven.price@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: steven.price@arm.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave.Martin@arm.com, mark.rutland@arm.com, tglx@linutronix.de, qemu-devel@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, richard.henderson@linaro.org, peter.maydell@linaro.org, drjones@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Received-SPF: pass client-ip=198.145.29.99; envelope-from=maz@kernel.org; helo=mail.kernel.org X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H2=-0.001, 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 , 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 Fri, 18 Jun 2021 14:28:22 +0100, Steven Price wrote: > > Add a new VM feature 'KVM_ARM_CAP_MTE' which enables memory tagging > for a VM. This will expose the feature to the guest and automatically > tag memory pages touched by the VM as PG_mte_tagged (and clear the tag > storage) to ensure that the guest cannot see stale tags, and so that > the tags are correctly saved/restored across swap. > > Actually exposing the new capability to user space happens in a later > patch. > > Signed-off-by: Steven Price > --- > arch/arm64/include/asm/kvm_emulate.h | 3 ++ > arch/arm64/include/asm/kvm_host.h | 3 ++ > arch/arm64/kvm/hyp/exception.c | 3 +- > arch/arm64/kvm/mmu.c | 62 +++++++++++++++++++++++++++- > arch/arm64/kvm/sys_regs.c | 7 ++++ > include/uapi/linux/kvm.h | 1 + > 6 files changed, 77 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index f612c090f2e4..6bf776c2399c 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -84,6 +84,9 @@ static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu) > if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) || > vcpu_el1_is_32bit(vcpu)) > vcpu->arch.hcr_el2 |= HCR_TID2; > + > + if (kvm_has_mte(vcpu->kvm)) > + vcpu->arch.hcr_el2 |= HCR_ATA; > } > > static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu) > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 7cd7d5c8c4bc..afaa5333f0e4 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -132,6 +132,8 @@ struct kvm_arch { > > u8 pfr0_csv2; > u8 pfr0_csv3; > + /* Memory Tagging Extension enabled for the guest */ > + bool mte_enabled; > }; > > struct kvm_vcpu_fault_info { > @@ -769,6 +771,7 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu); > #define kvm_arm_vcpu_sve_finalized(vcpu) \ > ((vcpu)->arch.flags & KVM_ARM64_VCPU_SVE_FINALIZED) > > +#define kvm_has_mte(kvm) (system_supports_mte() && (kvm)->arch.mte_enabled) > #define kvm_vcpu_has_pmu(vcpu) \ > (test_bit(KVM_ARM_VCPU_PMU_V3, (vcpu)->arch.features)) > > diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c > index 73629094f903..56426565600c 100644 > --- a/arch/arm64/kvm/hyp/exception.c > +++ b/arch/arm64/kvm/hyp/exception.c > @@ -112,7 +112,8 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, > new |= (old & PSR_C_BIT); > new |= (old & PSR_V_BIT); > > - // TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests) > + if (kvm_has_mte(vcpu->kvm)) > + new |= PSR_TCO_BIT; > > new |= (old & PSR_DIT_BIT); > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index c5d1f3c87dbd..f5305b7561ad 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -822,6 +822,45 @@ transparent_hugepage_adjust(struct kvm_memory_slot *memslot, > return PAGE_SIZE; > } > > +/* > + * The page will be mapped in stage 2 as Normal Cacheable, so the VM will be > + * able to see the page's tags and therefore they must be initialised first. If > + * PG_mte_tagged is set, tags have already been initialised. > + * > + * The race in the test/set of the PG_mte_tagged flag is handled by: > + * - preventing VM_SHARED mappings in a memslot with MTE preventing two VMs > + * racing to santise the same page > + * - mmap_lock protects between a VM faulting a page in and the VMM performing > + * an mprotect() to add VM_MTE > + */ > +static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn, > + unsigned long size) > +{ > + unsigned long i, nr_pages = size >> PAGE_SHIFT; > + struct page *page; > + > + if (!kvm_has_mte(kvm)) > + return 0; > + > + /* > + * pfn_to_online_page() is used to reject ZONE_DEVICE pages > + * that may not support tags. > + */ > + page = pfn_to_online_page(pfn); > + > + if (!page) > + return -EFAULT; > + > + for (i = 0; i < nr_pages; i++, page++) { > + if (!test_bit(PG_mte_tagged, &page->flags)) { > + mte_clear_page_tags(page_address(page)); > + set_bit(PG_mte_tagged, &page->flags); > + } > + } > + > + return 0; > +} > + > static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > struct kvm_memory_slot *memslot, unsigned long hva, > unsigned long fault_status) > @@ -971,8 +1010,16 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (writable) > prot |= KVM_PGTABLE_PROT_W; > > - if (fault_status != FSC_PERM && !device) > + if (fault_status != FSC_PERM && !device) { > + /* Check the VMM hasn't introduced a new VM_SHARED VMA */ > + if (kvm_has_mte(kvm) && vma->vm_flags & VM_SHARED) > + return -EINVAL; nit: I'd rather we return -EFAULT here. That's consistent with other cases where we can't satisfy the mapping. Thanks, M. -- Without deviation from the norm, progress is not possible. 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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 AED75C48BE5 for ; Mon, 21 Jun 2021 09:01:09 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 1CD9A61002 for ; Mon, 21 Jun 2021 09:01:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1CD9A61002 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 9E2934019D; Mon, 21 Jun 2021 05:01:07 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SKgk7WRXqddi; Mon, 21 Jun 2021 05:01:06 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0D3404025B; Mon, 21 Jun 2021 05:01:06 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 020F14024F for ; Mon, 21 Jun 2021 05:01:05 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HdJWTY5VpmPE for ; Mon, 21 Jun 2021 05:01:03 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 849D94019D for ; Mon, 21 Jun 2021 05:01:03 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8069161002; Mon, 21 Jun 2021 09:01:02 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1lvFng-008omp-Gs; Mon, 21 Jun 2021 10:01:00 +0100 Date: Mon, 21 Jun 2021 10:01:00 +0100 Message-ID: <87a6njd22b.wl-maz@kernel.org> From: Marc Zyngier To: Steven Price Subject: Re: [PATCH v16 3/7] KVM: arm64: Introduce MTE VM feature In-Reply-To: <20210618132826.54670-4-steven.price@arm.com> References: <20210618132826.54670-1-steven.price@arm.com> <20210618132826.54670-4-steven.price@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: steven.price@arm.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave.Martin@arm.com, mark.rutland@arm.com, tglx@linutronix.de, qemu-devel@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, richard.henderson@linaro.org, peter.maydell@linaro.org, drjones@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false 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 Fri, 18 Jun 2021 14:28:22 +0100, Steven Price wrote: > > Add a new VM feature 'KVM_ARM_CAP_MTE' which enables memory tagging > for a VM. This will expose the feature to the guest and automatically > tag memory pages touched by the VM as PG_mte_tagged (and clear the tag > storage) to ensure that the guest cannot see stale tags, and so that > the tags are correctly saved/restored across swap. > > Actually exposing the new capability to user space happens in a later > patch. > > Signed-off-by: Steven Price > --- > arch/arm64/include/asm/kvm_emulate.h | 3 ++ > arch/arm64/include/asm/kvm_host.h | 3 ++ > arch/arm64/kvm/hyp/exception.c | 3 +- > arch/arm64/kvm/mmu.c | 62 +++++++++++++++++++++++++++- > arch/arm64/kvm/sys_regs.c | 7 ++++ > include/uapi/linux/kvm.h | 1 + > 6 files changed, 77 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index f612c090f2e4..6bf776c2399c 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -84,6 +84,9 @@ static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu) > if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) || > vcpu_el1_is_32bit(vcpu)) > vcpu->arch.hcr_el2 |= HCR_TID2; > + > + if (kvm_has_mte(vcpu->kvm)) > + vcpu->arch.hcr_el2 |= HCR_ATA; > } > > static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu) > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 7cd7d5c8c4bc..afaa5333f0e4 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -132,6 +132,8 @@ struct kvm_arch { > > u8 pfr0_csv2; > u8 pfr0_csv3; > + /* Memory Tagging Extension enabled for the guest */ > + bool mte_enabled; > }; > > struct kvm_vcpu_fault_info { > @@ -769,6 +771,7 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu); > #define kvm_arm_vcpu_sve_finalized(vcpu) \ > ((vcpu)->arch.flags & KVM_ARM64_VCPU_SVE_FINALIZED) > > +#define kvm_has_mte(kvm) (system_supports_mte() && (kvm)->arch.mte_enabled) > #define kvm_vcpu_has_pmu(vcpu) \ > (test_bit(KVM_ARM_VCPU_PMU_V3, (vcpu)->arch.features)) > > diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c > index 73629094f903..56426565600c 100644 > --- a/arch/arm64/kvm/hyp/exception.c > +++ b/arch/arm64/kvm/hyp/exception.c > @@ -112,7 +112,8 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, > new |= (old & PSR_C_BIT); > new |= (old & PSR_V_BIT); > > - // TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests) > + if (kvm_has_mte(vcpu->kvm)) > + new |= PSR_TCO_BIT; > > new |= (old & PSR_DIT_BIT); > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index c5d1f3c87dbd..f5305b7561ad 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -822,6 +822,45 @@ transparent_hugepage_adjust(struct kvm_memory_slot *memslot, > return PAGE_SIZE; > } > > +/* > + * The page will be mapped in stage 2 as Normal Cacheable, so the VM will be > + * able to see the page's tags and therefore they must be initialised first. If > + * PG_mte_tagged is set, tags have already been initialised. > + * > + * The race in the test/set of the PG_mte_tagged flag is handled by: > + * - preventing VM_SHARED mappings in a memslot with MTE preventing two VMs > + * racing to santise the same page > + * - mmap_lock protects between a VM faulting a page in and the VMM performing > + * an mprotect() to add VM_MTE > + */ > +static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn, > + unsigned long size) > +{ > + unsigned long i, nr_pages = size >> PAGE_SHIFT; > + struct page *page; > + > + if (!kvm_has_mte(kvm)) > + return 0; > + > + /* > + * pfn_to_online_page() is used to reject ZONE_DEVICE pages > + * that may not support tags. > + */ > + page = pfn_to_online_page(pfn); > + > + if (!page) > + return -EFAULT; > + > + for (i = 0; i < nr_pages; i++, page++) { > + if (!test_bit(PG_mte_tagged, &page->flags)) { > + mte_clear_page_tags(page_address(page)); > + set_bit(PG_mte_tagged, &page->flags); > + } > + } > + > + return 0; > +} > + > static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > struct kvm_memory_slot *memslot, unsigned long hva, > unsigned long fault_status) > @@ -971,8 +1010,16 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (writable) > prot |= KVM_PGTABLE_PROT_W; > > - if (fault_status != FSC_PERM && !device) > + if (fault_status != FSC_PERM && !device) { > + /* Check the VMM hasn't introduced a new VM_SHARED VMA */ > + if (kvm_has_mte(kvm) && vma->vm_flags & VM_SHARED) > + return -EINVAL; nit: I'd rather we return -EFAULT here. That's consistent with other cases where we can't satisfy the mapping. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ 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=-14.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 0CE0FC48BE5 for ; Mon, 21 Jun 2021 09:02:48 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CDA6E611B0 for ; 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Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lvFno-002n1T-RM; Mon, 21 Jun 2021 09:01:08 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1lvFnk-002n0Z-IE for linux-arm-kernel@lists.infradead.org; Mon, 21 Jun 2021 09:01:06 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8069161002; Mon, 21 Jun 2021 09:01:02 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1lvFng-008omp-Gs; Mon, 21 Jun 2021 10:01:00 +0100 Date: Mon, 21 Jun 2021 10:01:00 +0100 Message-ID: <87a6njd22b.wl-maz@kernel.org> From: Marc Zyngier To: Steven Price 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 , Andrew Jones Subject: Re: [PATCH v16 3/7] KVM: arm64: Introduce MTE VM feature In-Reply-To: <20210618132826.54670-4-steven.price@arm.com> References: <20210618132826.54670-1-steven.price@arm.com> <20210618132826.54670-4-steven.price@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: steven.price@arm.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave.Martin@arm.com, mark.rutland@arm.com, tglx@linutronix.de, qemu-devel@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, richard.henderson@linaro.org, peter.maydell@linaro.org, drjones@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210621_020104_705101_D78E989E X-CRM114-Status: GOOD ( 38.06 ) 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 Fri, 18 Jun 2021 14:28:22 +0100, Steven Price wrote: > > Add a new VM feature 'KVM_ARM_CAP_MTE' which enables memory tagging > for a VM. This will expose the feature to the guest and automatically > tag memory pages touched by the VM as PG_mte_tagged (and clear the tag > storage) to ensure that the guest cannot see stale tags, and so that > the tags are correctly saved/restored across swap. > > Actually exposing the new capability to user space happens in a later > patch. > > Signed-off-by: Steven Price > --- > arch/arm64/include/asm/kvm_emulate.h | 3 ++ > arch/arm64/include/asm/kvm_host.h | 3 ++ > arch/arm64/kvm/hyp/exception.c | 3 +- > arch/arm64/kvm/mmu.c | 62 +++++++++++++++++++++++++++- > arch/arm64/kvm/sys_regs.c | 7 ++++ > include/uapi/linux/kvm.h | 1 + > 6 files changed, 77 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index f612c090f2e4..6bf776c2399c 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -84,6 +84,9 @@ static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu) > if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) || > vcpu_el1_is_32bit(vcpu)) > vcpu->arch.hcr_el2 |= HCR_TID2; > + > + if (kvm_has_mte(vcpu->kvm)) > + vcpu->arch.hcr_el2 |= HCR_ATA; > } > > static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu) > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 7cd7d5c8c4bc..afaa5333f0e4 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -132,6 +132,8 @@ struct kvm_arch { > > u8 pfr0_csv2; > u8 pfr0_csv3; > + /* Memory Tagging Extension enabled for the guest */ > + bool mte_enabled; > }; > > struct kvm_vcpu_fault_info { > @@ -769,6 +771,7 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu); > #define kvm_arm_vcpu_sve_finalized(vcpu) \ > ((vcpu)->arch.flags & KVM_ARM64_VCPU_SVE_FINALIZED) > > +#define kvm_has_mte(kvm) (system_supports_mte() && (kvm)->arch.mte_enabled) > #define kvm_vcpu_has_pmu(vcpu) \ > (test_bit(KVM_ARM_VCPU_PMU_V3, (vcpu)->arch.features)) > > diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c > index 73629094f903..56426565600c 100644 > --- a/arch/arm64/kvm/hyp/exception.c > +++ b/arch/arm64/kvm/hyp/exception.c > @@ -112,7 +112,8 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, > new |= (old & PSR_C_BIT); > new |= (old & PSR_V_BIT); > > - // TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests) > + if (kvm_has_mte(vcpu->kvm)) > + new |= PSR_TCO_BIT; > > new |= (old & PSR_DIT_BIT); > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index c5d1f3c87dbd..f5305b7561ad 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -822,6 +822,45 @@ transparent_hugepage_adjust(struct kvm_memory_slot *memslot, > return PAGE_SIZE; > } > > +/* > + * The page will be mapped in stage 2 as Normal Cacheable, so the VM will be > + * able to see the page's tags and therefore they must be initialised first. If > + * PG_mte_tagged is set, tags have already been initialised. > + * > + * The race in the test/set of the PG_mte_tagged flag is handled by: > + * - preventing VM_SHARED mappings in a memslot with MTE preventing two VMs > + * racing to santise the same page > + * - mmap_lock protects between a VM faulting a page in and the VMM performing > + * an mprotect() to add VM_MTE > + */ > +static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn, > + unsigned long size) > +{ > + unsigned long i, nr_pages = size >> PAGE_SHIFT; > + struct page *page; > + > + if (!kvm_has_mte(kvm)) > + return 0; > + > + /* > + * pfn_to_online_page() is used to reject ZONE_DEVICE pages > + * that may not support tags. > + */ > + page = pfn_to_online_page(pfn); > + > + if (!page) > + return -EFAULT; > + > + for (i = 0; i < nr_pages; i++, page++) { > + if (!test_bit(PG_mte_tagged, &page->flags)) { > + mte_clear_page_tags(page_address(page)); > + set_bit(PG_mte_tagged, &page->flags); > + } > + } > + > + return 0; > +} > + > static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > struct kvm_memory_slot *memslot, unsigned long hva, > unsigned long fault_status) > @@ -971,8 +1010,16 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > if (writable) > prot |= KVM_PGTABLE_PROT_W; > > - if (fault_status != FSC_PERM && !device) > + if (fault_status != FSC_PERM && !device) { > + /* Check the VMM hasn't introduced a new VM_SHARED VMA */ > + if (kvm_has_mte(kvm) && vma->vm_flags & VM_SHARED) > + return -EINVAL; nit: I'd rather we return -EFAULT here. That's consistent with other cases where we can't satisfy the mapping. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel