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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id EB4F1CA5FA5 for ; Wed, 30 Sep 2026 00:35:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Cr6UdQKdI0xls4OlaLkP7rmWD8zhk3VYrwsH9krw7jM=; b=liQff3ZQfKjxDRTYlDRQD8Ditf j8SMqTce3gv1vQR7UMwbtl2J34jDcF3h0UVfKnxG0/rwiJdrPyekzYltDWQCuiMbCI+PCTPbvVTpx 0tz+BSy1OZumoqRtKcvQgMvIDDxzZ4m6qySUrTQt06MiarMH1S18S0cLCIkTCF6Om5u5D4M4CP/S4 duKOueq+/81LQ4H0e32RA0JzxMYVnLOK7VjB+YJF9BBXjcvX6gKWe5eJwMcarVxN44/TdTG4y4LGV Kh8/0wNI0hK/tgwx9RGDNqnmm5o8t3q91zEIOrTd504RKz3BGIFLFRH80WNxmxOd76wChFsy9s+oR qou5lsgw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBiI5-00000004pLU-2IZ7; Wed, 30 Sep 2026 00:35:21 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBiI1-00000004pLF-3b69 for linux-arm-kernel@lists.infradead.org; Wed, 30 Sep 2026 00:35:17 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3E44A41700; Wed, 30 Sep 2026 00:35:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3C5E1F000FF; Wed, 30 Sep 2026 00:35:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790728517; bh=Cr6UdQKdI0xls4OlaLkP7rmWD8zhk3VYrwsH9krw7jM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Y7R0imuU10TDOyA5h5xY8NunTH92rKR594grKtQDyTajkI0sTgxH0QtQqcpBT27uK v/jDcULaKuymQGkyFvycV2q25HWMoizg99vQU9Ktr08NMf/k6gMLY7jzNc0T+/UEeV 9KMQ5hsKDvYFsxePGoJC5mTkxMk7mT1/w+3SYdIJc7Kuz/Ogzq74/VIHss+BdgO+Vg vliQ6n3zIZJcT11CWqF7ymubvoOv5TXY6cpYQHc1LIJ70Bn9e5yvzlhDACFxCtMP9T ilwweYwv9xkWcYcYpQ9cZjp6kp2+fUaixo6Z4pK8YLv3Ng4Nbkul7R6rHI9ANhZdSp +ELyy7HJgVzpA== Date: Tue, 29 Sep 2026 17:35:15 -0700 From: Oliver Upton To: Tian Zheng Cc: maz@kernel.org, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, pbonzini@redhat.com, leo.bras@arm.com, yuzenghui@huawei.com, wangzhou1@hisilicon.com, yangjinqian1@huawei.com, caijian11@h-partners.com, liuyonglong@huawei.com, tangchengchang@huawei.com, yezhenyu2@huawei.com, yubihong@huawei.com, linuxarm@huawei.com, joey.gouly@arm.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, seiden@linux.ibm.com, suzuki.poulose@arm.com, fuad.tabba@linux.dev, mark.rutland@arm.com, seanjc@google.com, rdunlap@infradead.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, skhan@linuxfoundation.org Subject: Re: [PATCH v5 02/15] KVM: arm64: Add KVM_PGTABLE_PROT_DIRTY Message-ID: References: <20260929103655.85107-1-zhengtian10@huawei.com> <20260929103655.85107-3-zhengtian10@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260929103655.85107-3-zhengtian10@huawei.com> 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Sep 29, 2026 at 06:36:42PM +0800, Tian Zheng wrote: > @@ -731,8 +731,12 @@ static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot p > if (prot & KVM_PGTABLE_PROT_R) > attr |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R; > > - if (prot & KVM_PGTABLE_PROT_W) > - attr |= KVM_PTE_LEAF_ATTR_HI_S2_DBM | KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W; > + if (prot & KVM_PGTABLE_PROT_W) { > + attr |= KVM_PTE_LEAF_ATTR_HI_S2_DBM; > + > + if (prot & KVM_PGTABLE_PROT_DIRTY) > + attr |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W; > + } Can you introduce the dirty state first? You're temporarily setting DBM+S2AP[1] as a workaround in the preceding patch. Then we can have it encoded such that when FEAT_HAFDBS is implemented: KVM_PGTABLE_PROT_W => KVM_PTE_LEAF_ATTR_HI_S2_DBM KVM_PGTABLE_PROT_DIRTY => KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W And if FEAT_HAFDBS is *not* implemented: KVM_PGTABLE_PROT_W => KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W KVM_PGTABLE_PROT_DIRTY => KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W i.e. aliasing both to bit 7. Thanks, Oliver > if (!kvm_lpa2_is_enabled()) > attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh); > @@ -753,9 +757,13 @@ enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte) > > if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R) > prot |= KVM_PGTABLE_PROT_R; > - if (pte & KVM_PTE_LEAF_ATTR_HI_S2_DBM) > + if (pte & KVM_PTE_LEAF_ATTR_HI_S2_DBM) { > prot |= KVM_PGTABLE_PROT_W; > > + if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W) > + prot |= KVM_PGTABLE_PROT_DIRTY; > + } > + > switch (FIELD_GET(KVM_PTE_LEAF_ATTR_HI_S2_XN, pte)) { > case 0b00: > prot |= KVM_PGTABLE_PROT_PX | KVM_PGTABLE_PROT_UX; > @@ -1288,7 +1296,6 @@ static int stage2_update_leaf_attrs(struct kvm_pgtable *pgt, u64 addr, > int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size) > { > return stage2_update_leaf_attrs(pgt, addr, size, 0, > - KVM_PTE_LEAF_ATTR_HI_S2_DBM | > KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W, > NULL, NULL, > KVM_PGTABLE_WALK_IGNORE_EAGAIN); > @@ -1368,8 +1375,12 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr, > if (prot & KVM_PGTABLE_PROT_R) > set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R; > > - if (prot & KVM_PGTABLE_PROT_W) > - set |= KVM_PTE_LEAF_ATTR_HI_S2_DBM | KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W; > + if (prot & KVM_PGTABLE_PROT_W) { > + set |= KVM_PTE_LEAF_ATTR_HI_S2_DBM; > + > + if (prot & KVM_PGTABLE_PROT_DIRTY) > + set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W; > + } > > if (prot & KVM_PGTABLE_PROT_X) { > ret = stage2_set_xn_attr(prot, &xn); > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 2d44cd6a5aed..698a87e85a6d 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1221,7 +1221,9 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa, > struct kvm_pgtable *pgt = mmu->pgt; > enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE | > KVM_PGTABLE_PROT_R | > - (writable ? KVM_PGTABLE_PROT_W : 0); > + (writable ? > + (KVM_PGTABLE_PROT_W | KVM_PGTABLE_PROT_DIRTY) : > + 0); > > if (is_protected_kvm_enabled()) > return -EPERM; > @@ -1587,7 +1589,7 @@ static enum kvm_pgtable_prot adjust_nested_fault_perms(struct kvm_s2_trans *nest > enum kvm_pgtable_prot prot) > { > if (!kvm_s2_trans_writable(nested)) > - prot &= ~KVM_PGTABLE_PROT_W; > + prot &= ~(KVM_PGTABLE_PROT_W | KVM_PGTABLE_PROT_DIRTY); > if (!kvm_s2_trans_readable(nested)) > prot &= ~KVM_PGTABLE_PROT_R; > > @@ -1658,7 +1660,7 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd) > } > > if (!(s2fd->memslot->flags & KVM_MEM_READONLY)) > - prot |= KVM_PGTABLE_PROT_W; > + prot |= KVM_PGTABLE_PROT_W | KVM_PGTABLE_PROT_DIRTY; > > if (s2fd->nested) > prot = adjust_nested_fault_perms(s2fd->nested, prot); > @@ -1690,10 +1692,17 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd) > } > > out_unlock: > + /* > + * Dirty the folio for any write-permitting mapping: hardware can > + * promote a writable-clean entry to writable-dirty without a VM > + * exit, so a clean release could lose a guest write at reclaim. > + * The dirty bitmap is only marked for mappings installed dirty, > + * or pre-copy would treat every writable page as dirty. > + */ > kvm_release_faultin_page(kvm, page, !!ret, prot & KVM_PGTABLE_PROT_W); > kvm_fault_unlock(kvm); > > - if ((prot & KVM_PGTABLE_PROT_W) && !ret) > + if ((prot & KVM_PGTABLE_PROT_DIRTY) && !ret) > mark_page_dirty_in_slot(kvm, s2fd->memslot, gfn); > > return ret != -EAGAIN ? ret : 0; > @@ -1993,11 +2002,14 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd, > > *prot = KVM_PGTABLE_PROT_R; > > - if (s2vi->map_writable && (s2vi->device || > - !memslot_is_logging(s2fd->memslot) || > - kvm_is_write_fault(s2fd->vcpu))) > + if (s2vi->map_writable) { > *prot |= KVM_PGTABLE_PROT_W; > > + if (s2vi->device || !memslot_is_logging(s2fd->memslot) || > + kvm_is_write_fault(s2fd->vcpu)) > + *prot |= KVM_PGTABLE_PROT_DIRTY; > + } > + > if (s2fd->nested) > *prot = adjust_nested_fault_perms(s2fd->nested, *prot); > > @@ -2028,7 +2040,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, > void *memcache) > { > enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_SHARED; > - bool writable = prot & KVM_PGTABLE_PROT_W; > + bool dirty = prot & KVM_PGTABLE_PROT_DIRTY; > struct kvm *kvm = s2fd->vcpu->kvm; > struct kvm_pgtable *pgt; > long perm_fault_granule; > @@ -2091,7 +2103,11 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, > } > > out_unlock: > - kvm_release_faultin_page(kvm, s2vi->page, !!ret, writable); > + /* > + * Speculative folio dirtying: W, not DIRTY, per the contract > + * documented in kvm_release_faultin_page(). > + */ > + kvm_release_faultin_page(kvm, s2vi->page, !!ret, prot & KVM_PGTABLE_PROT_W); > kvm_fault_unlock(kvm); > > /* > @@ -2099,7 +2115,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, > * making sure we adjust the canonical IPA if the mapping size has > * been updated (via a THP upgrade, for example). > */ > - if (writable && !ret) { > + if (dirty && !ret) { > phys_addr_t ipa = gfn_to_gpa(get_canonical_gfn(s2fd, s2vi)); > ipa &= ~(mapping_size - 1); > mark_page_dirty_in_slot(kvm, s2fd->memslot, gpa_to_gfn(ipa)); > diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c > index b0cb8d84a9e9..a1251e252b4f 100644 > --- a/arch/arm64/kvm/ptdump.c > +++ b/arch/arm64/kvm/ptdump.c > @@ -45,6 +45,12 @@ static const struct ptdump_prot_bits stage2_pte_bits[] = { > .set = "W", > .clear = " ", > }, > + { > + .mask = KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W, > + .val = KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W, > + .set = "D", > + .clear = "C", > + }, > { > .mask = KVM_PTE_LEAF_ATTR_HI_S2_XN, > .val = 0b00UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN), > -- > 2.43.0 >