From patchwork Fri Sep 29 15:01:39 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: George Dunlap X-Patchwork-Id: 9978263 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 98D8E60311 for ; Fri, 29 Sep 2017 15:04:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8BBA828446 for ; Fri, 29 Sep 2017 15:04:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 809D3284C9; Fri, 29 Sep 2017 15:04:24 +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 1CE2028446 for ; Fri, 29 Sep 2017 15:04:23 +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 1dxwnu-0003jN-Ou; Fri, 29 Sep 2017 15:02:14 +0000 Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dxwnt-0003gy-H7 for xen-devel@lists.xenproject.org; Fri, 29 Sep 2017 15:02:13 +0000 Received: from [193.109.254.147] by server-10.bemta-6.messagelabs.com id 72/EF-03642-4706EC95; Fri, 29 Sep 2017 15:02:12 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprIIsWRWlGSWpSXmKPExsXitHSDvW5Rwrl Ig87dYhbft0xmcmD0OPzhCksAYxRrZl5SfkUCa8aReZ2MBSvUK57tn8LSwLhdvouRk0NCwF/i +IapbCA2m4CexLzjX1m6GDk4RARUJG7vNehi5OJgFnjPKNHz4C4LSI2wgLvE8vkNTCA2i4Cqx LUznWBxXgEbiVNzprBAzJSXOPfgNjOIzSlgK7GpvxvMFgKqeXbtLjuErSqx+MFRdoheQYmTM5 +A9TILSEgcfPGCeQIj7ywkqVlIUgsYmVYxahSnFpWlFukameolFWWmZ5TkJmbm6BoamOnlphY XJ6an5iQmFesl5+duYgQGDwMQ7GBctSDwEKMkB5OSKK9A7LlIIb6k/JTKjMTijPii0pzU4kOM MhwcShK8RfFAOcGi1PTUirTMHGAYw6QlOHiURHg5QdK8xQWJucWZ6RCpU4y6HB037/5hEmLJy 89LlRLnFQUpEgApyijNgxsBi6lLjLJSwryMQEcJ8RSkFuVmlqDKv2IU52BUEuZtBZnCk5lXAr fpFdARTEBHTJ54BuSIkkSElFQD46ZLbSZy+okuEQtqHm8+lbHWvnOjpt+mF59+NFt9CvisLa3 I3bsia8Z9y1nZHmvkwjVcVXbYCf2Y0Cu7/t2cuBNtDjEMwl6H9/wVfuzVeWYlJ//SXwVr3vad mayWWvXPPO3/p2vs7oyVFx89sz1xlnVVv7JLg9rlCTLLvXtN0tlWLHS76XbCQ4mlOCPRUIu5q DgRAEg/UDekAgAA X-Env-Sender: prvs=438a79e6a=George.Dunlap@citrix.com X-Msg-Ref: server-13.tower-27.messagelabs.com!1506697326!109688636!2 X-Originating-IP: [66.165.176.63] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogNjYuMTY1LjE3Ni42MyA9PiAzMDYwNDg=\n, received_headers: No Received headers X-StarScan-Received: X-StarScan-Version: 9.4.45; banners=-,-,- X-VirusChecked: Checked Received: (qmail 39766 invoked from network); 29 Sep 2017 15:02:10 -0000 Received: from smtp02.citrix.com (HELO SMTP02.CITRIX.COM) (66.165.176.63) by server-13.tower-27.messagelabs.com with RC4-SHA encrypted SMTP; 29 Sep 2017 15:02:10 -0000 X-IronPort-AV: E=Sophos;i="5.42,452,1500940800"; d="scan'208";a="449785856" From: George Dunlap To: Date: Fri, 29 Sep 2017 16:01:39 +0100 Message-ID: <20170929150144.7602-4-george.dunlap@citrix.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170929150144.7602-1-george.dunlap@citrix.com> References: <20170929150144.7602-1-george.dunlap@citrix.com> MIME-Version: 1.0 Cc: Sergey Dyasli , Kevin Tian , Jan Beulich , Andrew Cooper , George Dunlap , Jun Nakajima Subject: [Xen-devel] [PATCH 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 --- v2: - Merged patch 9 and 10 ("x86/np2m: add p2m_get_nestedp2m_locked()" and "x86/np2m: improve nestedhvm_hap_nested_page_fault()") - Updated commit message - Fix comment style in nestedhap_fix_p2m() CC: Andrew Cooper CC: Jan Beulich CC: Jun Nakajima CC: Kevin Tian --- xen/arch/x86/mm/hap/nested_hap.c | 31 +++++++++++++------------------ xen/arch/x86/mm/p2m.c | 12 +++++++++--- xen/include/asm-x86/p2m.h | 2 ++ 3 files changed, 24 insertions(+), 21 deletions(-) diff --git a/xen/arch/x86/mm/hap/nested_hap.c b/xen/arch/x86/mm/hap/nested_hap.c index ed137fa784..844b32f702 100644 --- a/xen/arch/x86/mm/hap/nested_hap.c +++ b/xen/arch/x86/mm/hap/nested_hap.c @@ -101,28 +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); + gfn = (L2_gpa >> PAGE_SHIFT) & mask; + mfn = _mfn((L0_gpa >> PAGE_SHIFT) & mask); - rc = p2m_set_entry(p2m, gfn, mfn, page_order, p2mt, p2ma); - } + rc = p2m_set_entry(p2m, gfn, mfn, page_order, p2mt, p2ma); p2m_unlock(p2m); @@ -212,7 +207,6 @@ 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, @@ -278,6 +272,7 @@ 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); 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 85874ab401..4a1c10c130 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().