From patchwork Fri May 31 09:35:44 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 10969841 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6A0DB1398 for ; Fri, 31 May 2019 09:37:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5760228987 for ; Fri, 31 May 2019 09:37:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B16928C5A; Fri, 31 May 2019 09:37:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id D3ED928987 for ; Fri, 31 May 2019 09:37:30 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hWdwz-0003Nq-Eh; Fri, 31 May 2019 09:35:49 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hWdwy-0003Nh-E9 for xen-devel@lists.xenproject.org; Fri, 31 May 2019 09:35:48 +0000 X-Inumbo-ID: 77d4f4d8-8387-11e9-8980-bc764e045a96 Received: from prv1-mh.provo.novell.com (unknown [137.65.248.33]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTPS id 77d4f4d8-8387-11e9-8980-bc764e045a96; Fri, 31 May 2019 09:35:46 +0000 (UTC) Received: from INET-PRV1-MTA by prv1-mh.provo.novell.com with Novell_GroupWise; Fri, 31 May 2019 03:35:46 -0600 Message-Id: <5CF0F5700200007800233DB4@prv1-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 18.1.1 Date: Fri, 31 May 2019 03:35:44 -0600 From: "Jan Beulich" To: "xen-devel" References: <5CF0F33A0200007800233D8F@prv1-mh.provo.novell.com> In-Reply-To: <5CF0F33A0200007800233D8F@prv1-mh.provo.novell.com> Mime-Version: 1.0 Content-Disposition: inline Subject: [Xen-devel] [PATCH 2/2] dom_cow is needed for mem-sharing only X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Stefano Stabellini , WeiLiu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , Tim Deegan , Julien Grall , Tamas K Lengyel Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP A couple of adjustments are needed to code checking for dom_cow, but since there are pretty few it is probably better to adjust those than to set up and keep around a never used domain. Take the opportunity and tighten a BUG_ON() in emul-priv-op.c:read_cr(). (Arguably this perhaps shouldn't be a BUG_ON() in the first place.) Signed-off-by: Jan Beulich --- While for now this avoids creating the domain on Arm only, Tamas'es patch switching to CONFIG_MEM_SHARING will make x86 leverage this too. --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -967,8 +967,8 @@ get_page_from_l1e( return flip; } - if ( unlikely( (real_pg_owner != pg_owner) && - (real_pg_owner != dom_cow) ) ) + if ( unlikely((real_pg_owner != pg_owner) && + (!dom_cow || (real_pg_owner != dom_cow))) ) { /* * Let privileged domains transfer the right to map their target --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -568,7 +568,8 @@ struct page_info *p2m_get_page_from_gfn( } else if ( !get_page(page, p2m->domain) && /* Page could be shared */ - (!p2m_is_shared(*t) || !get_page(page, dom_cow)) ) + (!dom_cow || !p2m_is_shared(*t) || + !get_page(page, dom_cow)) ) page = NULL; } p2m_read_unlock(p2m); @@ -941,7 +942,8 @@ guest_physmap_add_entry(struct domain *d /* Then, look for m->p mappings for this range and deal with them */ for ( i = 0; i < (1UL << page_order); i++ ) { - if ( page_get_owner(mfn_to_page(mfn_add(mfn, i))) == dom_cow ) + if ( dom_cow && + page_get_owner(mfn_to_page(mfn_add(mfn, i))) == dom_cow ) { /* This is no way to add a shared page to your physmap! */ gdprintk(XENLOG_ERR, "Adding shared mfn %lx directly to dom%d physmap not allowed.\n", --- a/xen/arch/x86/pv/emul-priv-op.c +++ b/xen/arch/x86/pv/emul-priv-op.c @@ -723,8 +723,8 @@ static int read_cr(unsigned int reg, uns unmap_domain_page(pl4e); *val = compat_pfn_to_cr3(mfn_to_gmfn(currd, mfn_x(mfn))); } - /* PTs should not be shared */ - BUG_ON(page_get_owner(mfn_to_page(mfn)) == dom_cow); + /* PTs should be owned by their domains */ + BUG_ON(page_get_owner(mfn_to_page(mfn)) != currd); return X86EMUL_OKAY; } } --- a/xen/common/domain.c +++ b/xen/common/domain.c @@ -74,7 +74,9 @@ integer_param("hardware_dom", hardware_d /* Private domain structs for DOMID_XEN, DOMID_IO, etc. */ struct domain *__read_mostly dom_xen; struct domain *__read_mostly dom_io; +#ifdef CONFIG_HAS_MEM_SHARING struct domain *__read_mostly dom_cow; +#endif struct vcpu *idle_vcpu[NR_CPUS] __read_mostly; @@ -544,12 +546,14 @@ void __init setup_special_domains(void) dom_io = domain_create(DOMID_IO, NULL, false); BUG_ON(IS_ERR(dom_io)); +#ifdef CONFIG_HAS_MEM_SHARING /* * Initialise our COW domain. * This domain owns sharable pages. */ dom_cow = domain_create(DOMID_COW, NULL, false); BUG_ON(IS_ERR(dom_cow)); +#endif } void domain_update_node_affinity(struct domain *d) --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -1095,7 +1095,7 @@ map_grant_ref( host_map_created = true; } } - else if ( owner == rd || owner == dom_cow ) + else if ( owner == rd || (dom_cow && owner == dom_cow) ) { if ( (op->flags & GNTMAP_device_map) && !(op->flags & GNTMAP_readonly) ) { --- a/xen/include/xen/mm.h +++ b/xen/include/xen/mm.h @@ -644,6 +644,9 @@ static inline void filtered_flush_tlb_ma /* Private domain structs for DOMID_XEN, DOMID_IO, etc. */ extern struct domain *dom_xen, *dom_io, *dom_cow; +#ifndef CONFIG_HAS_MEM_SHARING +# define dom_cow NULL +#endif enum XENSHARE_flags { SHARE_rw,