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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 18A30C4338F for ; Tue, 10 Aug 2021 04:41:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E39E960E78 for ; Tue, 10 Aug 2021 04:41:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237250AbhHJEl4 (ORCPT ); Tue, 10 Aug 2021 00:41:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40362 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236606AbhHJElx (ORCPT ); Tue, 10 Aug 2021 00:41:53 -0400 Received: from mail-ot1-x329.google.com (mail-ot1-x329.google.com [IPv6:2607:f8b0:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98120C0613D3 for ; Mon, 9 Aug 2021 21:41:32 -0700 (PDT) Received: by mail-ot1-x329.google.com with SMTP id v10-20020a9d604a0000b02904fa9613b53dso9684757otj.6 for ; Mon, 09 Aug 2021 21:41:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=3fI6+zpWNL9dvCk7s7yKEGMLw+f473R8fD+YQvZUssc=; b=S+9Be2ujBEjAO/Cvjx/UoNPdG/2jmG1oVR6I33Uq9jZ1NgAngrD/qybkdKuZbFIUru RmEH1sk6mPxKrWmER7c0s1VmWjpRpQn3gZDirUtMGP9Z0sNbj2JJID4ZFeYYPl5mkiRg C1nTSfkVtHFUjt5iL4chObDwqYID6tRYm2xdP2xEV254TTd/RC2Uh/XN8iGScwrt3R8G 3e5gZVSoYOh2fgQ32mD7rEgV+ln4JAD+Vq1nRWnUCkl4UvFZOCgOB/SC07++0N2AKJ2y wwHtMe2M2zIibmu5h2lhnoiUWlqjjGpV5pv2iLIykt1zx2Mg2qAy7qWvJS7OuXpJD3Op S7aA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=3fI6+zpWNL9dvCk7s7yKEGMLw+f473R8fD+YQvZUssc=; b=BWzv1JghWlrnWjuuvm4MleOyYlhrUWxHBXcAheDFrXaxjs23yf4wtomuJoa2cEzjsM mBYFhtIthQgyGHmqjKhRJ0NzEg/pV6tlGET2h7wgDgt1wC9dM6xHy9+YGKtXjj+l0LYg 2dxx8aHDETTPVx4Om+stM8f++aOWZ9aG0r8wwXCT0t3FCP2HUVgmNSTwXxT0IMFSJBSQ SHDqnOtLG7QIFhDmAAiVfAEQ1xTpY9zOxJ7lhROV9Emu/EydiVmVbYGMRzwZ6epf9Uks aItPiwMPHaHfoY6mFmJ2914NIt64xILHhWj0W11AI6MybKIzdSTPE4kx38jt7NB7hKaZ F2OA== X-Gm-Message-State: AOAM533N8qb4NKz7bvYWeQoJM/ygIgAtc7UvvRJH7z9bUeJRshA07hS+ u0YpMUWbSr5FkfjVJoNchLMup8J/CFdNLC4R15QYTA== X-Google-Smtp-Source: ABdhPJxKEk6fQCA2o1JXEptjeSlu9BoabMv4CVKRUJiXnXZ0Wgi0UVzPLAEc4ytF0a6GM96rp0y6yz6REwL92K31Ij8= X-Received: by 2002:a9d:7359:: with SMTP id l25mr988748otk.52.1628570491801; Mon, 09 Aug 2021 21:41:31 -0700 (PDT) MIME-Version: 1.0 References: <20210809152448.1810400-1-qperret@google.com> <20210809152448.1810400-18-qperret@google.com> In-Reply-To: <20210809152448.1810400-18-qperret@google.com> From: Fuad Tabba Date: Tue, 10 Aug 2021 06:40:55 +0200 Message-ID: Subject: Re: [PATCH v4 17/21] KVM: arm64: Mark host bss and rodata section as shared To: Quentin Perret Cc: maz@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, ardb@kernel.org, qwandor@google.com, dbrazdil@google.com, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Quentin, On Mon, Aug 9, 2021 at 5:25 PM Quentin Perret wrote: > > As the hypervisor maps the host's .bss and .rodata sections in its > stage-1, make sure to tag them as shared in hyp and host page-tables. > > But since the hypervisor relies on the presence of these mappings, we > cannot let the host in complete control of the memory regions -- it > must not unshare or donate them to another entity for example. To > prevent this, let's transfer the ownership of those ranges to the > hypervisor itself, and share the pages back with the host. > > Signed-off-by: Quentin Perret > --- Reviewed-by: Fuad Tabba Thanks, /fuad > arch/arm64/kvm/hyp/nvhe/setup.c | 82 +++++++++++++++++++++++++++++---- > 1 file changed, 74 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c > index 0b574d106519..57c27846320f 100644 > --- a/arch/arm64/kvm/hyp/nvhe/setup.c > +++ b/arch/arm64/kvm/hyp/nvhe/setup.c > @@ -58,6 +58,7 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size, > { > void *start, *end, *virt = hyp_phys_to_virt(phys); > unsigned long pgt_size = hyp_s1_pgtable_pages() << PAGE_SHIFT; > + enum kvm_pgtable_prot prot; > int ret, i; > > /* Recreate the hyp page-table using the early page allocator */ > @@ -83,10 +84,6 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size, > if (ret) > return ret; > > - ret = pkvm_create_mappings(__start_rodata, __end_rodata, PAGE_HYP_RO); > - if (ret) > - return ret; > - > ret = pkvm_create_mappings(__hyp_rodata_start, __hyp_rodata_end, PAGE_HYP_RO); > if (ret) > return ret; > @@ -95,10 +92,6 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size, > if (ret) > return ret; > > - ret = pkvm_create_mappings(__hyp_bss_end, __bss_stop, PAGE_HYP_RO); > - if (ret) > - return ret; > - > ret = pkvm_create_mappings(virt, virt + size, PAGE_HYP); > if (ret) > return ret; > @@ -117,6 +110,24 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size, > return ret; > } > > + /* > + * Map the host's .bss and .rodata sections RO in the hypervisor, but > + * transfer the ownership from the host to the hypervisor itself to > + * make sure it can't be donated or shared with another entity. > + * > + * The ownership transition requires matching changes in the host > + * stage-2. This will be done later (see finalize_host_mappings()) once > + * the hyp_vmemmap is addressable. > + */ > + prot = pkvm_mkstate(PAGE_HYP_RO, PKVM_PAGE_SHARED_OWNED); > + ret = pkvm_create_mappings(__start_rodata, __end_rodata, prot); > + if (ret) > + return ret; > + > + ret = pkvm_create_mappings(__hyp_bss_end, __bss_stop, prot); > + if (ret) > + return ret; > + > return 0; > } > > @@ -148,6 +159,57 @@ static void hpool_put_page(void *addr) > hyp_put_page(&hpool, addr); > } > > +static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level, > + kvm_pte_t *ptep, > + enum kvm_pgtable_walk_flags flag, > + void * const arg) > +{ > + enum kvm_pgtable_prot prot; > + enum pkvm_page_state state; > + kvm_pte_t pte = *ptep; > + phys_addr_t phys; > + > + if (!kvm_pte_valid(pte)) > + return 0; > + > + if (level != (KVM_PGTABLE_MAX_LEVELS - 1)) > + return -EINVAL; > + > + phys = kvm_pte_to_phys(pte); > + if (!addr_is_memory(phys)) > + return 0; > + > + /* > + * Adjust the host stage-2 mappings to match the ownership attributes > + * configured in the hypervisor stage-1. > + */ > + state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(pte)); > + switch (state) { > + case PKVM_PAGE_OWNED: > + return host_stage2_set_owner_locked(phys, PAGE_SIZE, pkvm_hyp_id); > + case PKVM_PAGE_SHARED_OWNED: > + prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_BORROWED); > + break; > + case PKVM_PAGE_SHARED_BORROWED: > + prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_OWNED); > + break; > + default: > + return -EINVAL; > + } > + > + return host_stage2_idmap_locked(phys, PAGE_SIZE, prot); > +} > + > +static int finalize_host_mappings(void) > +{ > + struct kvm_pgtable_walker walker = { > + .cb = finalize_host_mappings_walker, > + .flags = KVM_PGTABLE_WALK_LEAF, > + }; > + > + return kvm_pgtable_walk(&pkvm_pgtable, 0, BIT(pkvm_pgtable.ia_bits), &walker); > +} > + > void __noreturn __pkvm_init_finalise(void) > { > struct kvm_host_data *host_data = this_cpu_ptr(&kvm_host_data); > @@ -167,6 +229,10 @@ void __noreturn __pkvm_init_finalise(void) > if (ret) > goto out; > > + ret = finalize_host_mappings(); > + if (ret) > + goto out; > + > pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) { > .zalloc_page = hyp_zalloc_hyp_page, > .phys_to_virt = hyp_phys_to_virt, > -- > 2.32.0.605.g8dce9f2422-goog >