From nobody Tue Feb 10 01:31:36 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=arm.com ARC-Seal: i=1; a=rsa-sha256; t=1612536092; cv=none; d=zohomail.com; s=zohoarc; b=QDy/hywBi42c2Q5YBG+4LMb1G+Njym4AEjPEUV8/of9yXK4WCt0B+WNeu9MgjaXFTunHRWUnsVdUQ+W07hDshl7B3ZFhJp4xwh5/gtWWkeCKEYpc43lqtH81TtVKr2LO4ginG4f6ZE/skKfxdcORFvzFcM2PmrFJhCdgjW1YiiE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1612536092; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=6Z5CBISq8JYeD0M9tphDr3a0+sOpoCYVnrMJHdM0gDw=; b=FaDrZszrs8Ujvltv3GQOcp9niar1gF8QiImc7ftr/eARgi0LpasLq2KZ7IC+cGBrHPlj6yPsvphvZSjCBXXZOfcJ4jiomRvxquzrVKP/bnLtGcl1SoqLd4Gd1sVEjsBU9H8u1YltW6L4YJVda9ltJiFuuMS38xXhwdNjoFR4aLM= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 16125360920481018.7992229845772; Fri, 5 Feb 2021 06:41:32 -0800 (PST) Received: from localhost ([::1]:57656 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l81gm-0002eM-Ls for importer@patchew.org; Fri, 05 Feb 2021 09:02:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:60748) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l81d1-000700-54 for qemu-devel@nongnu.org; Fri, 05 Feb 2021 08:58:31 -0500 Received: from foss.arm.com ([217.140.110.172]:53050) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l81cy-000765-SE for qemu-devel@nongnu.org; Fri, 05 Feb 2021 08:58:30 -0500 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 0CB7411B3; Fri, 5 Feb 2021 05:58:28 -0800 (PST) Received: from e112269-lin.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2301E3F719; Fri, 5 Feb 2021 05:58:25 -0800 (PST) From: Steven Price To: Catalin Marinas , Marc Zyngier , Will Deacon Subject: [PATCH v8 2/5] arm64: kvm: Introduce MTE VM feature Date: Fri, 5 Feb 2021 13:58:00 +0000 Message-Id: <20210205135803.48321-3-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210205135803.48321-1-steven.price@arm.com> References: <20210205135803.48321-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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, 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, Dave Martin , Juan Quintela , Richard Henderson , linux-kernel@vger.kernel.org, Steven Price , James Morse , Julien Thierry , Thomas Gleixner , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" 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 | 16 ++++++++++++++++ arch/arm64/kvm/sys_regs.c | 3 ++- include/uapi/linux/kvm.h | 1 + 6 files changed, 27 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 |=3D HCR_TID2; + + if (kvm_has_mte(vcpu->kvm)) + vcpu->arch.hcr_el2 |=3D HCR_ATA; } =20 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 11beda85ee7e..302ebc61d8ac 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -132,6 +132,8 @@ struct kvm_arch { =20 u8 pfr0_csv2; u8 pfr0_csv3; + /* Memory Tagging Extension enabled for the guest */ + bool mte_enabled; }; =20 struct kvm_vcpu_fault_info { @@ -745,6 +747,7 @@ 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) =20 +#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)) =20 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, un= signed long target_mode, new |=3D (old & PSR_C_BIT); new |=3D (old & PSR_V_BIT); =20 - // TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests) + if (kvm_has_mte(vcpu->kvm)) + new |=3D PSR_TCO_BIT; =20 new |=3D (old & PSR_DIT_BIT); =20 diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 7d2257cc5438..6076a1ab41d9 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -879,6 +879,22 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_= addr_t fault_ipa, if (vma_pagesize =3D=3D PAGE_SIZE && !force_pte) vma_pagesize =3D transparent_hugepage_adjust(memslot, hva, &pfn, &fault_ipa); + + if (kvm_has_mte(kvm) && pfn_valid(pfn)) { + /* + * VM will be able to see the page's tags, so we must ensure + * they have been initialised. if PG_mte_tagged is set, tags + * have already been initialised. + */ + struct page *page =3D pfn_to_page(pfn); + unsigned long i, nr_pages =3D vma_pagesize >> PAGE_SHIFT; + + for (i =3D 0; i < nr_pages; i++, page++) { + if (!test_and_set_bit(PG_mte_tagged, &page->flags)) + mte_clear_page_tags(page_address(page)); + } + } + if (writable) { prot |=3D KVM_PGTABLE_PROT_W; kvm_set_pfn_dirty(pfn); diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 3313dedfa505..bb5525bbf1ca 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1029,7 +1029,8 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, val &=3D ~(0xfUL << ID_AA64PFR0_CSV3_SHIFT); val |=3D ((u64)vcpu->kvm->arch.pfr0_csv3 << ID_AA64PFR0_CSV3_SHIFT); } else if (id =3D=3D SYS_ID_AA64PFR1_EL1) { - val &=3D ~(0xfUL << ID_AA64PFR1_MTE_SHIFT); + if (!kvm_has_mte(vcpu->kvm)) + val &=3D ~(0xfUL << ID_AA64PFR1_MTE_SHIFT); } else if (id =3D=3D SYS_ID_AA64ISAR1_EL1 && !vcpu_has_ptrauth(vcpu)) { val &=3D ~((0xfUL << ID_AA64ISAR1_APA_SHIFT) | (0xfUL << ID_AA64ISAR1_API_SHIFT) | diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 886802b8ffba..de737d5102ca 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1056,6 +1056,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190 #define KVM_CAP_SYS_HYPERV_CPUID 191 #define KVM_CAP_DIRTY_LOG_RING 192 +#define KVM_CAP_ARM_MTE 193 =20 #ifdef KVM_CAP_IRQ_ROUTING =20 --=20 2.20.1