From patchwork Tue Oct 3 15:20:59 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergey Dyasli X-Patchwork-Id: 9983065 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0E7216038E for ; Tue, 3 Oct 2017 15:23:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 004E62889D for ; Tue, 3 Oct 2017 15:23:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E975E289E1; Tue, 3 Oct 2017 15:23:49 +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=-4.2 required=2.0 tests=BAYES_00, 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 AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 79DE02889D for ; Tue, 3 Oct 2017 15:23:49 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dzP0X-0002wi-Rz; Tue, 03 Oct 2017 15:21:17 +0000 Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dzP0V-0002va-QG for xen-devel@lists.xen.org; Tue, 03 Oct 2017 15:21:15 +0000 Received: from [85.158.137.68] by server-16.bemta-3.messagelabs.com id 4C/A3-01778-BEAA3D95; Tue, 03 Oct 2017 15:21:15 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprIIsWRWlGSWpSXmKPExsXitHRDpO6rVZc jDb5+kLJY8nExiwOjx9Hdv5kCGKNYM/OS8isSWDNeNr9nLXijWvHowlPWBsZmuS5GTg4JAX+J R6/OsoPYbAJ6Ehtnv2ICsUUEZCVWd80BinNxMAvMZZaYuaGXFSQhLOAj8adhOlgRi4CKxMsLj 4HiHBy8AjYSBx/nQ8yUl9jVdhGsnFPAVmLKsfksILYQUMn3L3sYIWxVidcvdoHFeQUEJU7OfA JmMwtISBx88YJ5AiPvLCSpWUhSCxiZVjFqFKcWlaUW6Rqa6yUVZaZnlOQmZuboGhoY6+WmFhc npqfmJCYV6yXn525iBAYPAxDsYHx52vMQoyQHk5Io7+tllyOF+JLyUyozEosz4otKc1KLDzHK cHAoSfD6rgTKCRalpqdWpGXmAMMYJi3BwaMkwmu5AijNW1yQmFucmQ6ROsWoy9Fx8+4fJiGWv Py8VClx3iKQGQIgRRmleXAjYDF1iVFWSpiXEegoIZ6C1KLczBJU+VeM4hyMSsK8pSBTeDLzSu A2vQI6ggnoiDldF0COKElESEk1MG6S1Hm4NuPa77tMHfv6BLj/9lyTWnZ4suncY+vf5ck+KVr aUrh/eZDfSglup1UvP21tuJy+s/KJnuz1x77HprixlvQfPvsuhnVNyYmnK5hn/jlpP33B372C kep97k679r9okOPZ7xjHYPuV59DUDzucJW3VF+zRvt/0PftF8u9H8+bu4pB1t5ivxFKckWiox VxUnAgAPy5IKaQCAAA= X-Env-Sender: prvs=4422f64de=sergey.dyasli@citrix.com X-Msg-Ref: server-6.tower-31.messagelabs.com!1507044071!79182981!2 X-Originating-IP: [66.165.176.89] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogNjYuMTY1LjE3Ni44OSA9PiAyMDMwMDc=\n, received_headers: No Received headers X-StarScan-Received: X-StarScan-Version: 9.4.45; banners=-,-,- X-VirusChecked: Checked Received: (qmail 37736 invoked from network); 3 Oct 2017 15:21:14 -0000 Received: from smtp.citrix.com (HELO SMTP.CITRIX.COM) (66.165.176.89) by server-6.tower-31.messagelabs.com with RC4-SHA encrypted SMTP; 3 Oct 2017 15:21:14 -0000 X-IronPort-AV: E=Sophos;i="5.42,474,1500940800"; d="scan'208";a="442358099" From: Sergey Dyasli To: Date: Tue, 3 Oct 2017 16:20:59 +0100 Message-ID: <20171003152104.1432-5-sergey.dyasli@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20171003152104.1432-1-sergey.dyasli@citrix.com> References: <20171003152104.1432-1-sergey.dyasli@citrix.com> MIME-Version: 1.0 Cc: Sergey Dyasli , Kevin Tian , Jun Nakajima , George Dunlap , Andrew Cooper , Tim Deegan , George Dunlap , Jan Beulich , Boris Ostrovsky , Suravee Suthikulpanit Subject: [Xen-devel] [PATCH v3 4/9] x86/np2m: simplify nestedhvm_hap_nested_page_fault() X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP There is a possibility for nested_p2m to became stale between nestedhvm_hap_nested_page_fault() and nestedhap_fix_p2m(). At the moment this is handled by detecting such a race inside nestedhap_fix_p2m() and special-casing it. Instead, introduce p2m_get_nestedp2m_locked(), which will returned a still-locked p2m. This allows us to call nestedhap_fix_p2m() with the lock held and remove the code detecting the special-case. Signed-off-by: Sergey Dyasli Signed-off-by: George Dunlap Reviewed-by: George Dunlap --- v2 --> v3: - Moved p2m_unlock() out of nestedhap_fix_p2m() for balanced lock/unlock --- xen/arch/x86/mm/hap/nested_hap.c | 34 ++++++++++++++-------------------- xen/arch/x86/mm/p2m.c | 12 +++++++++--- xen/include/asm-x86/p2m.h | 2 ++ 3 files changed, 25 insertions(+), 23 deletions(-) diff --git a/xen/arch/x86/mm/hap/nested_hap.c b/xen/arch/x86/mm/hap/nested_hap.c index ed137fa784..d7277cccdc 100644 --- a/xen/arch/x86/mm/hap/nested_hap.c +++ b/xen/arch/x86/mm/hap/nested_hap.c @@ -101,30 +101,23 @@ nestedhap_fix_p2m(struct vcpu *v, struct p2m_domain *p2m, unsigned int page_order, p2m_type_t p2mt, p2m_access_t p2ma) { int rc = 0; + unsigned long gfn, mask; + mfn_t mfn; + ASSERT(p2m); ASSERT(p2m->set_entry); + ASSERT(p2m_locked_by_me(p2m)); - p2m_lock(p2m); - - /* If this p2m table has been flushed or recycled under our feet, - * leave it alone. We'll pick up the right one as we try to - * vmenter the guest. */ - if ( p2m->np2m_base == nhvm_vcpu_p2m_base(v) ) - { - unsigned long gfn, mask; - mfn_t mfn; + /* + * If this is a superpage mapping, round down both addresses to + * the start of the superpage. + */ + mask = ~((1UL << page_order) - 1); - /* If this is a superpage mapping, round down both addresses - * to the start of the superpage. */ - mask = ~((1UL << page_order) - 1); - - gfn = (L2_gpa >> PAGE_SHIFT) & mask; - mfn = _mfn((L0_gpa >> PAGE_SHIFT) & mask); - - rc = p2m_set_entry(p2m, gfn, mfn, page_order, p2mt, p2ma); - } + gfn = (L2_gpa >> PAGE_SHIFT) & mask; + mfn = _mfn((L0_gpa >> PAGE_SHIFT) & mask); - p2m_unlock(p2m); + rc = p2m_set_entry(p2m, gfn, mfn, page_order, p2mt, p2ma); if ( rc ) { @@ -212,7 +205,6 @@ nestedhvm_hap_nested_page_fault(struct vcpu *v, paddr_t *L2_gpa, uint8_t p2ma_21 = p2m_access_rwx; p2m = p2m_get_hostp2m(d); /* L0 p2m */ - nested_p2m = p2m_get_nestedp2m(v); /* walk the L1 P2M table */ rv = nestedhap_walk_L1_p2m(v, *L2_gpa, &L1_gpa, &page_order_21, &p2ma_21, @@ -278,8 +270,10 @@ nestedhvm_hap_nested_page_fault(struct vcpu *v, paddr_t *L2_gpa, p2ma_10 &= (p2m_access_t)p2ma_21; /* fix p2m_get_pagetable(nested_p2m) */ + nested_p2m = p2m_get_nestedp2m_locked(v); nestedhap_fix_p2m(v, nested_p2m, *L2_gpa, L0_gpa, page_order_20, p2mt_10, p2ma_10); + p2m_unlock(nested_p2m); return NESTEDHVM_PAGEFAULT_DONE; } diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c index d3e602de22..aa3182dec6 100644 --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -1813,7 +1813,7 @@ static void assign_np2m(struct vcpu *v, struct p2m_domain *p2m) } struct p2m_domain * -p2m_get_nestedp2m(struct vcpu *v) +p2m_get_nestedp2m_locked(struct vcpu *v) { struct nestedvcpu *nv = &vcpu_nestedhvm(v); struct domain *d = v->domain; @@ -1838,7 +1838,6 @@ p2m_get_nestedp2m(struct vcpu *v) hvm_asid_flush_vcpu(v); p2m->np2m_base = np2m_base; assign_np2m(v, p2m); - p2m_unlock(p2m); nestedp2m_unlock(d); return p2m; @@ -1854,12 +1853,19 @@ p2m_get_nestedp2m(struct vcpu *v) p2m->np2m_base = np2m_base; hvm_asid_flush_vcpu(v); assign_np2m(v, p2m); - p2m_unlock(p2m); nestedp2m_unlock(d); return p2m; } +struct p2m_domain *p2m_get_nestedp2m(struct vcpu *v) +{ + struct p2m_domain *p2m = p2m_get_nestedp2m_locked(v); + p2m_unlock(p2m); + + return p2m; +} + struct p2m_domain * p2m_get_p2m(struct vcpu *v) { diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h index 798295ec12..9a757792ee 100644 --- a/xen/include/asm-x86/p2m.h +++ b/xen/include/asm-x86/p2m.h @@ -363,6 +363,8 @@ struct p2m_domain { * Updates vCPU's n2pm to match its np2m_base in VMCx12 and returns that np2m. */ struct p2m_domain *p2m_get_nestedp2m(struct vcpu *v); +/* Similar to the above except that returned p2m is still write-locked */ +struct p2m_domain *p2m_get_nestedp2m_locked(struct vcpu *v); /* If vcpu is in host mode then behaviour matches p2m_get_hostp2m(). * If vcpu is in guest mode then behaviour matches p2m_get_nestedp2m().