From patchwork Mon Nov 30 10:31:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Oleksandr Tyshchenko X-Patchwork-Id: 11940163 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 DBB83C64E90 for ; Mon, 30 Nov 2020 10:44:42 +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 703F3204EF for ; Mon, 30 Nov 2020 10:44:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="XKXYxs6V" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 703F3204EF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.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.40935.74030 (Exim 4.92) (envelope-from ) id 1kjgfZ-0003uf-Ta; Mon, 30 Nov 2020 10:44:33 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 40935.74030; Mon, 30 Nov 2020 10:44:33 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kjgfZ-0003u5-Ec; Mon, 30 Nov 2020 10:44:33 +0000 Received: by outflank-mailman (input) for mailman id 40935; Mon, 30 Nov 2020 10:44:30 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kjgUi-0000Uu-Dz for xen-devel@lists.xenproject.org; Mon, 30 Nov 2020 10:33:20 +0000 Received: from mail-lj1-x241.google.com (unknown [2a00:1450:4864:20::241]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 6ae8ea99-6cfd-4cdd-ac5d-3e112cc031bc; Mon, 30 Nov 2020 10:32:16 +0000 (UTC) Received: by mail-lj1-x241.google.com with SMTP id o24so17027702ljj.6 for ; Mon, 30 Nov 2020 02:32:16 -0800 (PST) Received: from otyshchenko.www.tendawifi.com ([212.22.223.21]) by smtp.gmail.com with ESMTPSA id 136sm2399393lfb.62.2020.11.30.02.32.14 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Nov 2020 02:32:14 -0800 (PST) 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: 6ae8ea99-6cfd-4cdd-ac5d-3e112cc031bc DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=OKmGkMX/jIOJO9o6+1yYd5b6GcAGRnA31NMN1x/OSi4=; b=XKXYxs6V0uUIrdlAspHzTQGR3pmU8Ss17YPN4o2F4++GT9IJYtjEF760ralpDNSCm5 4V7W5UxP5PODamVWYK7FGDpE8gP5WcHwG9Q+zN6aOpbB7dp8/7B1M01IZCecvacPcWi/ 5tvgk2Lzp77zp57KvWRUXIGDu63XI0PiHQNWPdXeEH941F6tCF1zHDA+1+XZ6+fojrnz Cw4/kLix3wC4JtpSxuNGTNdEDkEKTvgyxNslcrWl0LH/SgAoDiw2Izv/kCtyGbSowy6Q pqzL1+HxTd/UtXhAhz3mks5CB9/io+fT5JiWOwBPHVVfCoZvcq0p5E+IVR1CUh4lj+NL G7PQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=OKmGkMX/jIOJO9o6+1yYd5b6GcAGRnA31NMN1x/OSi4=; b=KIZtWPaJjKRgs3GFYOQk3B+S9A7P93bpnguTd57DLbT+JLQoOGxq8z8S5+g5d0tHu2 2VPBCdimWfPImsOH57zFbJLrd+F4F1z06rX2VfQSxF8JbBhIkducHnrisNnWNGPu88D5 gLRVNYVqtkJDENceFiZ0gJVVFmoWX4lpKyYwg+PGddIOV4bjkfwAkeYySwkM9bEMwZ0l nXoUqw49lHzjqSlN6F5Gm0DlolKSdTiK0oZi0/5CEfI1XaIXQohjtarfWRorrNAx5wLw ESmXph8Z7H9bVRCMSWR/ff38Jr9pU4sb6BoySD7n8Bzw6/3sjH4TCaSic9GhVeCoEtvM uEfg== X-Gm-Message-State: AOAM532XwRViCvPuVaJHo7q7lfvN1VbUt/84sLfkdoV72JN4gfEhFmmx 2iT9rWNCfRg6bPomzeXDbzz6tNaAkqDeUg== X-Google-Smtp-Source: ABdhPJyMo+o0k5ozOLvlit07DgGXSuYm6EYjFCQns/RTQUDWl7b3OnGNV5QbcQGsq44W8TxhrbtePg== X-Received: by 2002:a2e:2286:: with SMTP id i128mr9141277lji.396.1606732335210; Mon, 30 Nov 2020 02:32:15 -0800 (PST) From: Oleksandr Tyshchenko To: xen-devel@lists.xenproject.org Cc: Oleksandr Tyshchenko , Stefano Stabellini , Julien Grall , Volodymyr Babchuk , Andrew Cooper , George Dunlap , Ian Jackson , Jan Beulich , Wei Liu , =?utf-8?q?Roger_Pau_?= =?utf-8?q?Monn=C3=A9?= , Julien Grall Subject: [PATCH V3 16/23] xen/mm: Handle properly reference in set_foreign_p2m_entry() on Arm Date: Mon, 30 Nov 2020 12:31:31 +0200 Message-Id: <1606732298-22107-17-git-send-email-olekstysh@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1606732298-22107-1-git-send-email-olekstysh@gmail.com> References: <1606732298-22107-1-git-send-email-olekstysh@gmail.com> MIME-Version: 1.0 From: Oleksandr Tyshchenko This patch implements reference counting of foreign entries in in set_foreign_p2m_entry() on Arm. This is a mandatory action if we want to run emulator (IOREQ server) in other than dom0 domain, as we can't trust it to do the right thing if it is not running in dom0. So we need to grab a reference on the page to avoid it disappearing. It is valid to always pass "p2m_map_foreign_rw" type to guest_physmap_add_entry() since the current and foreign domains would be always different. A case when they are equal would be rejected by rcu_lock_remote_domain_by_id(). Besides the similar comment in the code put a respective ASSERT() to catch incorrect usage in future. It was tested with IOREQ feature to confirm that all the pages given to this function belong to a domain, so we can use the same approach as for XENMAPSPACE_gmfn_foreign handling in xenmem_add_to_physmap_one(). This involves adding an extra parameter for the foreign domain to set_foreign_p2m_entry() and a helper to indicate whether the arch supports the reference counting of foreign entries and the restriction for the hardware domain in the common code can be skipped for it. Signed-off-by: Oleksandr Tyshchenko CC: Julien Grall Acked-by: Stefano Stabellini --- Please note, this is a split/cleanup/hardening of Julien's PoC: "Add support for Guest IO forwarding to a device emulator" Changes RFC -> V1: - new patch, was split from: "[RFC PATCH V1 04/12] xen/arm: Introduce arch specific bits for IOREQ/DM features" - rewrite a logic to handle properly reference in set_foreign_p2m_entry() instead of treating foreign entries as p2m_ram_rw Changes V1 -> V2: - rebase according to the recent changes to acquire_resource() - update patch description - introduce arch_refcounts_p2m() - add an explanation why p2m_map_foreign_rw is valid - move set_foreign_p2m_entry() to p2m-common.h - add const to new parameter Changes V2 -> V3: - update patch description - rename arch_refcounts_p2m() to arch_acquire_resource_check() - move comment to x86’s arch_acquire_resource_check() - return rc in Arm's set_foreign_p2m_entry() - put a respective ASSERT() into Arm's set_foreign_p2m_entry() --- --- xen/arch/arm/p2m.c | 24 ++++++++++++++++++++++++ xen/arch/x86/mm/p2m.c | 5 +++-- xen/common/memory.c | 10 +++------- xen/include/asm-arm/p2m.h | 19 +++++++++---------- xen/include/asm-x86/p2m.h | 16 +++++++++++++--- xen/include/xen/p2m-common.h | 4 ++++ 6 files changed, 56 insertions(+), 22 deletions(-) diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index 4eeb867..5b8d494 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -1380,6 +1380,30 @@ int guest_physmap_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn, return p2m_remove_mapping(d, gfn, (1 << page_order), mfn); } +int set_foreign_p2m_entry(struct domain *d, const struct domain *fd, + unsigned long gfn, mfn_t mfn) +{ + struct page_info *page = mfn_to_page(mfn); + int rc; + + if ( !get_page(page, fd) ) + return -EINVAL; + + /* + * It is valid to always use p2m_map_foreign_rw here as if this gets + * called then d != fd. A case when d == fd would be rejected by + * rcu_lock_remote_domain_by_id() earlier. Put a respective ASSERT() + * to catch incorrect usage in future. + */ + ASSERT(d != fd); + + rc = guest_physmap_add_entry(d, _gfn(gfn), mfn, 0, p2m_map_foreign_rw); + if ( rc ) + put_page(page); + + return rc; +} + static struct page_info *p2m_allocate_root(void) { struct page_info *page; diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c index 7a2ba82..4772c86 100644 --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -1321,7 +1321,8 @@ static int set_typed_p2m_entry(struct domain *d, unsigned long gfn_l, } /* Set foreign mfn in the given guest's p2m table. */ -int set_foreign_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn) +int set_foreign_p2m_entry(struct domain *d, const struct domain *fd, + unsigned long gfn, mfn_t mfn) { return set_typed_p2m_entry(d, gfn, mfn, PAGE_ORDER_4K, p2m_map_foreign, p2m_get_hostp2m(d)->default_access); @@ -2621,7 +2622,7 @@ int p2m_add_foreign(struct domain *tdom, unsigned long fgfn, * will update the m2p table which will result in mfn -> gpfn of dom0 * and not fgfn of domU. */ - rc = set_foreign_p2m_entry(tdom, gpfn, mfn); + rc = set_foreign_p2m_entry(tdom, fdom, gpfn, mfn); if ( rc ) gdprintk(XENLOG_WARNING, "set_foreign_p2m_entry failed. " "gpfn:%lx mfn:%lx fgfn:%lx td:%d fd:%d\n", diff --git a/xen/common/memory.c b/xen/common/memory.c index 3363c06..49e3001 100644 --- a/xen/common/memory.c +++ b/xen/common/memory.c @@ -1134,12 +1134,8 @@ static int acquire_resource( xen_pfn_t mfn_list[32]; int rc; - /* - * FIXME: Until foreign pages inserted into the P2M are properly - * reference counted, it is unsafe to allow mapping of - * resource pages unless the caller is the hardware domain. - */ - if ( paging_mode_translate(currd) && !is_hardware_domain(currd) ) + if ( paging_mode_translate(currd) && !is_hardware_domain(currd) && + !arch_acquire_resource_check() ) return -EACCES; if ( copy_from_guest(&xmar, arg, 1) ) @@ -1207,7 +1203,7 @@ static int acquire_resource( for ( i = 0; !rc && i < xmar.nr_frames; i++ ) { - rc = set_foreign_p2m_entry(currd, gfn_list[i], + rc = set_foreign_p2m_entry(currd, d, gfn_list[i], _mfn(mfn_list[i])); /* rc should be -EIO for any iteration other than the first */ if ( rc && i ) diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h index 28ca9a8..4f8056e 100644 --- a/xen/include/asm-arm/p2m.h +++ b/xen/include/asm-arm/p2m.h @@ -161,6 +161,15 @@ typedef enum { #endif #include +static inline bool arch_acquire_resource_check(void) +{ + /* + * The reference counting of foreign entries in set_foreign_p2m_entry() + * is supported on Arm. + */ + return true; +} + static inline void p2m_altp2m_check(struct vcpu *v, uint16_t idx) { @@ -392,16 +401,6 @@ static inline gfn_t gfn_next_boundary(gfn_t gfn, unsigned int order) return gfn_add(gfn, 1UL << order); } -static inline int set_foreign_p2m_entry(struct domain *d, unsigned long gfn, - mfn_t mfn) -{ - /* - * NOTE: If this is implemented then proper reference counting of - * foreign entries will need to be implemented. - */ - return -EOPNOTSUPP; -} - /* * A vCPU has cache enabled only when the MMU is enabled and data cache * is enabled. diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h index 4603560..8d2dc22 100644 --- a/xen/include/asm-x86/p2m.h +++ b/xen/include/asm-x86/p2m.h @@ -382,6 +382,19 @@ struct p2m_domain { #endif #include +static inline bool arch_acquire_resource_check(void) +{ + /* + * The reference counting of foreign entries in set_foreign_p2m_entry() + * is not supported on x86. + * + * FIXME: Until foreign pages inserted into the P2M are properly + * reference counted, it is unsafe to allow mapping of + * resource pages unless the caller is the hardware domain. + */ + return false; +} + /* * Updates vCPU's n2pm to match its np2m_base in VMCx12 and returns that np2m. */ @@ -647,9 +660,6 @@ int p2m_finish_type_change(struct domain *d, int p2m_is_logdirty_range(struct p2m_domain *, unsigned long start, unsigned long end); -/* Set foreign entry in the p2m table (for priv-mapping) */ -int set_foreign_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn); - /* Set mmio addresses in the p2m table (for pass-through) */ int set_mmio_p2m_entry(struct domain *d, gfn_t gfn, mfn_t mfn, unsigned int order); diff --git a/xen/include/xen/p2m-common.h b/xen/include/xen/p2m-common.h index 58031a6..b4bc709 100644 --- a/xen/include/xen/p2m-common.h +++ b/xen/include/xen/p2m-common.h @@ -3,6 +3,10 @@ #include +/* Set foreign entry in the p2m table */ +int set_foreign_p2m_entry(struct domain *d, const struct domain *fd, + unsigned long gfn, mfn_t mfn); + /* Remove a page from a domain's p2m table */ int __must_check guest_physmap_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,