From patchwork Tue Jan 12 19:48:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrew Cooper X-Patchwork-Id: 12014777 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 195D7C43331 for ; Tue, 12 Jan 2021 19:49:32 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 D323923117 for ; Tue, 12 Jan 2021 19:49:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D323923117 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.65963.116992 (Exim 4.92) (envelope-from ) id 1kzPfP-0006VR-RZ; Tue, 12 Jan 2021 19:49:23 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 65963.116992; Tue, 12 Jan 2021 19:49:23 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kzPfP-0006VF-Nk; Tue, 12 Jan 2021 19:49:23 +0000 Received: by outflank-mailman (input) for mailman id 65963; Tue, 12 Jan 2021 19:49:22 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kzPfO-00064W-9y for xen-devel@lists.xenproject.org; Tue, 12 Jan 2021 19:49:22 +0000 Received: from esa4.hc3370-68.iphmx.com (unknown [216.71.155.144]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 7eab4440-a59f-415b-afa0-34947c85bb91; Tue, 12 Jan 2021 19:49:04 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 7eab4440-a59f-415b-afa0-34947c85bb91 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1610480944; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=X/PbmeBQtvy5GUaatFDXs/925CHjaXa3SUYUSvIYvMM=; b=TN21oHGZ2S5vtOKscXv5estJXUrSyeBuCrudbzB8I/1g0MqHjs8cB7X8 8eIKoR3oxmhGXQ3mYP0ggzD0tbE9LLN8eFJIe72F04zdvf3j3GErm4P33 cHMyFcOyr056sl9yAlWrYnFffj7TDJGv/YoyGvpSBqxLQaBUFIzhGeKyj w=; Authentication-Results: esa4.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: erp6TVIUXQsw2FD39zaUKacuDPNFyTXqH89xkma3aulfGmx5YlkArPzhtgL5Uz3cGPV9BnoFu7 sOfJ735l6Uzyy3TqfaogeolcLhCzovuwzLn50Ag6GzO+S2YBDDpetlZTriQ327YhgtFlobFlHn NT5YkPTctsYLJ+uq+TIZUvwQgALIq2KSPM5t3pYmDpAkfhTK/BB/8YdSVv/9/Pe6Ocma35So70 PmsnMb7fyeFH4UTlus6cW4hVvPFot44oOLGmr4tIKfvOPw8RiDPva5gbJcFQk8mQyhgs611/rI FLU= X-SBRS: 5.2 X-MesageID: 36235816 X-Ironport-Server: esa4.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.79,342,1602561600"; d="scan'208";a="36235816" From: Andrew Cooper To: Xen-devel CC: Andrew Cooper , George Dunlap , Ian Jackson , Jan Beulich , Stefano Stabellini , Wei Liu , Julien Grall , Paul Durrant , =?utf-8?q?Micha?= =?utf-8?q?=C5=82_Leszczy=C5=84ski?= , Hubert Jasudowicz , Tamas K Lengyel Subject: [PATCH v3 2/7] xen/memory: Fix acquire_resource size semantics Date: Tue, 12 Jan 2021 19:48:36 +0000 Message-ID: <20210112194841.1537-3-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210112194841.1537-1-andrew.cooper3@citrix.com> References: <20210112194841.1537-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Calling XENMEM_acquire_resource with a NULL frame_list is a request for the size of the resource, but the returned 32 is bogus. If someone tries to follow it for XENMEM_resource_ioreq_server, the acquire call will fail as IOREQ servers currently top out at 2 frames, and it is only half the size of the default grant table limit for guests. Also, no users actually request a resource size, because it was never wired up in the sole implementaion of resource acquisition in Linux. Introduce a new resource_max_frames() to calculate the size of a resource, and implement it the IOREQ and grant subsystems. It is impossible to guarantee that a mapping call following a successful size call will succeed (e.g. The target IOREQ server gets destroyed, or the domain switches from grant v2 to v1). Document the restriction, and use the flexibility to simplify the paths to be lockless. Signed-off-by: Andrew Cooper Reviewed-by: Paul Durrant Reviewed-by: Jan Beulich --- CC: George Dunlap CC: Ian Jackson CC: Jan Beulich CC: Stefano Stabellini CC: Wei Liu CC: Julien Grall CC: Paul Durrant CC: Michał Leszczyński CC: Hubert Jasudowicz CC: Tamas K Lengyel v3: * Use const struct domain * * Fold goto out paths v2: * Spelling fixes * Add more local variables. * Don't return any status frames on ARM where v2 support is compiled out. --- xen/arch/x86/mm.c | 20 +++++++++++++++++ xen/common/grant_table.c | 23 ++++++++++++++++++++ xen/common/memory.c | 50 ++++++++++++++++++++++++++++++++----------- xen/include/asm-x86/mm.h | 3 +++ xen/include/public/memory.h | 16 ++++++++++---- xen/include/xen/grant_table.h | 8 +++++++ xen/include/xen/mm.h | 6 ++++++ 7 files changed, 109 insertions(+), 17 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 63e9fae919..7a2e94cd6f 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -4587,6 +4587,26 @@ static int handle_iomem_range(unsigned long s, unsigned long e, void *p) return err || s > e ? err : _handle_iomem_range(s, e, p); } +unsigned int arch_resource_max_frames( + const struct domain *d, unsigned int type, unsigned int id) +{ + unsigned int nr = 0; + + switch ( type ) + { +#ifdef CONFIG_HVM + case XENMEM_resource_ioreq_server: + if ( !is_hvm_domain(d) ) + break; + /* One frame for the buf-ioreq ring, and one frame per 128 vcpus. */ + nr = 1 + DIV_ROUND_UP(d->max_vcpus * sizeof(struct ioreq), PAGE_SIZE); + break; +#endif + } + + return nr; +} + int arch_acquire_resource(struct domain *d, unsigned int type, unsigned int id, unsigned long frame, unsigned int nr_frames, xen_pfn_t mfn_list[]) diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c index f560c250d7..bd99dddbf6 100644 --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -4013,6 +4013,29 @@ static int gnttab_get_shared_frame_mfn(struct domain *d, return 0; } +unsigned int gnttab_resource_max_frames(const struct domain *d, unsigned int id) +{ + const struct grant_table *gt = d->grant_table; + unsigned int nr = 0; + + /* Don't need the grant lock. This limit is fixed at domain create time. */ + switch ( id ) + { + case XENMEM_resource_grant_table_id_shared: + nr = gt->max_grant_frames; + break; + + case XENMEM_resource_grant_table_id_status: + if ( GNTTAB_MAX_VERSION < 2 ) + break; + + nr = grant_to_status_frames(gt->max_grant_frames); + break; + } + + return nr; +} + int gnttab_acquire_resource( struct domain *d, unsigned int id, unsigned long frame, unsigned int nr_frames, xen_pfn_t mfn_list[]) diff --git a/xen/common/memory.c b/xen/common/memory.c index 82cf7b41ee..beefa6a313 100644 --- a/xen/common/memory.c +++ b/xen/common/memory.c @@ -1052,6 +1052,26 @@ static long xatp_permission_check(struct domain *d, unsigned int space) return xsm_add_to_physmap(XSM_TARGET, current->domain, d); } +/* + * Return 0 on any kind of error. Caller converts to -EINVAL. + * + * All nonzero values should be repeatable (i.e. derived from some fixed + * property of the domain), and describe the full resource (i.e. mapping the + * result of this call will be the entire resource). + */ +static unsigned int resource_max_frames(const struct domain *d, + unsigned int type, unsigned int id) +{ + switch ( type ) + { + case XENMEM_resource_grant_table: + return gnttab_resource_max_frames(d, id); + + default: + return arch_resource_max_frames(d, type, id); + } +} + static int acquire_resource( XEN_GUEST_HANDLE_PARAM(xen_mem_acquire_resource_t) arg) { @@ -1063,6 +1083,7 @@ static int acquire_resource( * use-cases then per-CPU arrays or heap allocations may be required. */ xen_pfn_t mfn_list[32]; + unsigned int max_frames; int rc; /* @@ -1079,19 +1100,6 @@ static int acquire_resource( if ( xmar.pad != 0 ) return -EINVAL; - if ( guest_handle_is_null(xmar.frame_list) ) - { - if ( xmar.nr_frames ) - return -EINVAL; - - xmar.nr_frames = ARRAY_SIZE(mfn_list); - - if ( __copy_field_to_guest(arg, &xmar, nr_frames) ) - return -EFAULT; - - return 0; - } - if ( xmar.nr_frames > ARRAY_SIZE(mfn_list) ) return -E2BIG; @@ -1103,6 +1111,22 @@ static int acquire_resource( if ( rc ) goto out; + max_frames = resource_max_frames(d, xmar.type, xmar.id); + + rc = -EINVAL; + if ( !max_frames ) + goto out; + + if ( guest_handle_is_null(xmar.frame_list) ) + { + if ( xmar.nr_frames ) + goto out; + + xmar.nr_frames = max_frames; + rc = __copy_field_to_guest(arg, &xmar, nr_frames) ? -EFAULT : 0; + goto out; + } + switch ( xmar.type ) { case XENMEM_resource_grant_table: diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h index deeba75a1c..a40a7fa024 100644 --- a/xen/include/asm-x86/mm.h +++ b/xen/include/asm-x86/mm.h @@ -639,6 +639,9 @@ static inline bool arch_mfn_in_directmap(unsigned long mfn) return mfn <= (virt_to_mfn(eva - 1) + 1); } +unsigned int arch_resource_max_frames(const struct domain *d, + unsigned int type, unsigned int id); + int arch_acquire_resource(struct domain *d, unsigned int type, unsigned int id, unsigned long frame, unsigned int nr_frames, xen_pfn_t mfn_list[]); diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h index 21d483298e..d7eb34f167 100644 --- a/xen/include/public/memory.h +++ b/xen/include/public/memory.h @@ -639,10 +639,18 @@ struct xen_mem_acquire_resource { #define XENMEM_resource_grant_table_id_status 1 /* - * IN/OUT - As an IN parameter number of frames of the resource - * to be mapped. However, if the specified value is 0 and - * frame_list is NULL then this field will be set to the - * maximum value supported by the implementation on return. + * IN/OUT + * + * As an IN parameter number of frames of the resource to be mapped. + * + * When frame_list is NULL and nr_frames is 0, this is interpreted as a + * request for the size of the resource, which shall be returned in the + * nr_frames field. + * + * The size of a resource will never be zero, but a nonzero result doesn't + * guarantee that a subsequent mapping request will be successful. There + * are further type/id specific constraints which may change between the + * two calls. */ uint32_t nr_frames; uint32_t pad; diff --git a/xen/include/xen/grant_table.h b/xen/include/xen/grant_table.h index 5a2c75b880..015704bebc 100644 --- a/xen/include/xen/grant_table.h +++ b/xen/include/xen/grant_table.h @@ -57,6 +57,8 @@ int mem_sharing_gref_to_gfn(struct grant_table *gt, grant_ref_t ref, int gnttab_map_frame(struct domain *d, unsigned long idx, gfn_t gfn, mfn_t *mfn); +unsigned int gnttab_resource_max_frames(const struct domain *d, unsigned int id); + int gnttab_acquire_resource( struct domain *d, unsigned int id, unsigned long frame, unsigned int nr_frames, xen_pfn_t mfn_list[]); @@ -93,6 +95,12 @@ static inline int gnttab_map_frame(struct domain *d, unsigned long idx, return -EINVAL; } +static inline unsigned int gnttab_resource_max_frames( + const struct domain *d, unsigned int id) +{ + return 0; +} + static inline int gnttab_acquire_resource( struct domain *d, unsigned int id, unsigned long frame, unsigned int nr_frames, xen_pfn_t mfn_list[]) diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h index e62a5b726e..2a919fbcb4 100644 --- a/xen/include/xen/mm.h +++ b/xen/include/xen/mm.h @@ -703,6 +703,12 @@ static inline void put_page_alloc_ref(struct page_info *page) } #ifndef CONFIG_ARCH_ACQUIRE_RESOURCE +static inline unsigned int arch_resource_max_frames( + const struct domain *d, unsigned int type, unsigned int id) +{ + return 0; +} + static inline int arch_acquire_resource( struct domain *d, unsigned int type, unsigned int id, unsigned long frame, unsigned int nr_frames, xen_pfn_t mfn_list[])