From patchwork Thu Sep 26 09:45:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Xia, Hongyan" X-Patchwork-Id: 11162051 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B140113B1 for ; Thu, 26 Sep 2019 09:48:40 +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 8D2B6222C3 for ; Thu, 26 Sep 2019 09:48:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="cIxMP0I9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D2B6222C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1iDQMs-0003f0-Nc; Thu, 26 Sep 2019 09:47:22 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1iDQMs-0003es-Bk for xen-devel@lists.xenproject.org; Thu, 26 Sep 2019 09:47:22 +0000 X-Inumbo-ID: a308f41a-e042-11e9-bf31-bc764e2007e4 Received: from smtp-fw-2101.amazon.com (unknown [72.21.196.25]) by localhost (Halon) with ESMTPS id a308f41a-e042-11e9-bf31-bc764e2007e4; Thu, 26 Sep 2019 09:47:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1569491241; x=1601027241; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version; bh=ylxx4KY9/y4YFgv7nP3EOYtykrPz1aPjA0nz6rqmeOA=; b=cIxMP0I9O6KH+tTu30YsBHhPK5WwVO7jyv5CgUsZ1pklnU5tDJRl5YV9 W1JCCKXu0RhHaHQ6lOzUfi1sFpCAsPQjsWMcpylm8T+eBC6b1k6uaK1Xl 25uh0hL3TpiCja07XiL136JfSg7rHjGkNaI/Wd14pUh+ICO5oLvU8zddV E=; X-IronPort-AV: E=Sophos;i="5.64,551,1559520000"; d="scan'208";a="753354010" Received: from iad6-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-1d-474bcd9f.us-east-1.amazon.com) ([10.124.125.2]) by smtp-border-fw-out-2101.iad2.amazon.com with ESMTP; 26 Sep 2019 09:47:21 +0000 Received: from EX13MTAUWA001.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan2.iad.amazon.com [10.40.159.162]) by email-inbound-relay-1d-474bcd9f.us-east-1.amazon.com (Postfix) with ESMTPS id BD8ACA26EE; Thu, 26 Sep 2019 09:47:19 +0000 (UTC) Received: from EX13D20UWA001.ant.amazon.com (10.43.160.34) by EX13MTAUWA001.ant.amazon.com (10.43.160.58) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 26 Sep 2019 09:47:03 +0000 Received: from EX13MTAUWA001.ant.amazon.com (10.43.160.58) by EX13D20UWA001.ant.amazon.com (10.43.160.34) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 26 Sep 2019 09:47:02 +0000 Received: from u9d785c4ba99158.ant.amazon.com (10.125.106.58) by mail-relay.amazon.com (10.43.160.118) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Thu, 26 Sep 2019 09:47:01 +0000 From: To: Date: Thu, 26 Sep 2019 10:45:28 +0100 Message-ID: X-Mailer: git-send-email 2.17.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: Bulk Subject: [Xen-devel] [RFC PATCH 05/84] x86/mm: introduce l{1, 2}t local variables to modify_xen_mappings X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Andrew Cooper , Wei Liu , Wei Liu , Jan Beulich , =?utf-8?q?Roger_Pau_?= =?utf-8?q?Monn=C3=A9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" From: Wei Liu The pl2e and pl1e variables are heavily (ab)used in that function. It is fine at the moment because all page tables are always mapped so there is no need to track the life time of each variable. We will soon have the requirement to map and unmap page tables. We need to track the life time of each variable to avoid leakage. Introduce some l{1,2}t variables with limited scope so that we can track life time of pointers to xen page tables more easily. No functional change. Signed-off-by: Wei Liu --- xen/arch/x86/mm.c | 68 ++++++++++++++++++++++++++--------------------- 1 file changed, 38 insertions(+), 30 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 2ae8a7736f..063cacffb8 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -5428,6 +5428,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) if ( l3e_get_flags(*pl3e) & _PAGE_PSE ) { + l2_pgentry_t *l2t; + if ( l2_table_offset(v) == 0 && l1_table_offset(v) == 0 && ((e - v) >= (1UL << L3_PAGETABLE_SHIFT)) ) @@ -5443,11 +5445,11 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) } /* PAGE1GB: shatter the superpage and fall through. */ - pl2e = alloc_xen_pagetable(); - if ( !pl2e ) + l2t = alloc_xen_pagetable(); + if ( !l2t ) return -ENOMEM; for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ ) - l2e_write(pl2e + i, + l2e_write(l2t + i, l2e_from_pfn(l3e_get_pfn(*pl3e) + (i << PAGETABLE_ORDER), l3e_get_flags(*pl3e))); @@ -5456,14 +5458,14 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) if ( (l3e_get_flags(*pl3e) & _PAGE_PRESENT) && (l3e_get_flags(*pl3e) & _PAGE_PSE) ) { - l3e_write_atomic(pl3e, l3e_from_mfn(virt_to_mfn(pl2e), + l3e_write_atomic(pl3e, l3e_from_mfn(virt_to_mfn(l2t), __PAGE_HYPERVISOR)); - pl2e = NULL; + l2t = NULL; } if ( locking ) spin_unlock(&map_pgdir_lock); - if ( pl2e ) - free_xen_pagetable(pl2e); + if ( l2t ) + free_xen_pagetable(l2t); } /* @@ -5497,12 +5499,14 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) } else { + l1_pgentry_t *l1t; + /* PSE: shatter the superpage and try again. */ - pl1e = alloc_xen_pagetable(); - if ( !pl1e ) + l1t = alloc_xen_pagetable(); + if ( !l1t ) return -ENOMEM; for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ ) - l1e_write(&pl1e[i], + l1e_write(&l1t[i], l1e_from_pfn(l2e_get_pfn(*pl2e) + i, l2e_get_flags(*pl2e) & ~_PAGE_PSE)); if ( locking ) @@ -5510,19 +5514,19 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) if ( (l2e_get_flags(*pl2e) & _PAGE_PRESENT) && (l2e_get_flags(*pl2e) & _PAGE_PSE) ) { - l2e_write_atomic(pl2e, l2e_from_mfn(virt_to_mfn(pl1e), + l2e_write_atomic(pl2e, l2e_from_mfn(virt_to_mfn(l1t), __PAGE_HYPERVISOR)); - pl1e = NULL; + l1t = NULL; } if ( locking ) spin_unlock(&map_pgdir_lock); - if ( pl1e ) - free_xen_pagetable(pl1e); + if ( l1t ) + free_xen_pagetable(l1t); } } else { - l1_pgentry_t nl1e; + l1_pgentry_t nl1e, *l1t; /* * Ordinary 4kB mapping: The L2 entry has been verified to be @@ -5569,9 +5573,9 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) continue; } - pl1e = l2e_to_l1e(*pl2e); + l1t = l2e_to_l1e(*pl2e); for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ ) - if ( l1e_get_intpte(pl1e[i]) != 0 ) + if ( l1e_get_intpte(l1t[i]) != 0 ) break; if ( i == L1_PAGETABLE_ENTRIES ) { @@ -5580,7 +5584,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) if ( locking ) spin_unlock(&map_pgdir_lock); flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */ - free_xen_pagetable(pl1e); + free_xen_pagetable(l1t); } else if ( locking ) spin_unlock(&map_pgdir_lock); @@ -5609,21 +5613,25 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) continue; } - pl2e = l3e_to_l2e(*pl3e); - for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ ) - if ( l2e_get_intpte(pl2e[i]) != 0 ) - break; - if ( i == L2_PAGETABLE_ENTRIES ) { - /* Empty: zap the L3E and free the L2 page. */ - l3e_write_atomic(pl3e, l3e_empty()); - if ( locking ) + l2_pgentry_t *l2t; + + l2t = l3e_to_l2e(*pl3e); + for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ ) + if ( l2e_get_intpte(l2t[i]) != 0 ) + break; + if ( i == L2_PAGETABLE_ENTRIES ) + { + /* Empty: zap the L3E and free the L2 page. */ + l3e_write_atomic(pl3e, l3e_empty()); + if ( locking ) + spin_unlock(&map_pgdir_lock); + flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */ + free_xen_pagetable(l2t); + } + else if ( locking ) spin_unlock(&map_pgdir_lock); - flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */ - free_xen_pagetable(pl2e); } - else if ( locking ) - spin_unlock(&map_pgdir_lock); } flush_area(NULL, FLUSH_TLB_GLOBAL);