From patchwork Wed Oct 2 17:16:49 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Xia, Hongyan" X-Patchwork-Id: 11171693 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 4950F14DB for ; Wed, 2 Oct 2019 17:18:34 +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 250E2222BE for ; Wed, 2 Oct 2019 17:18:34 +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="XVK66bcX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 250E2222BE 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 1iFiFZ-0008G5-E4; Wed, 02 Oct 2019 17:17:17 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1iFiFY-0008Fs-S0 for xen-devel@lists.xenproject.org; Wed, 02 Oct 2019 17:17:16 +0000 X-Inumbo-ID: 788cd242-e538-11e9-8628-bc764e2007e4 Received: from smtp-fw-6001.amazon.com (unknown [52.95.48.154]) by localhost (Halon) with ESMTPS id 788cd242-e538-11e9-8628-bc764e2007e4; Wed, 02 Oct 2019 17:17:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1570036631; x=1601572631; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version; bh=tH0b4W+UWpzdh9E5CsarCcvHj0VbyzZplIDQB4UfEXA=; b=XVK66bcXYxzwTWx02BEab3p3G0j/dKbZ1x0+CMCsEd5F/MJVQHsTptFS 7EhHo4XM4qC1Cd8xWX7aFrdqtraG1mxx8yqmBde2Az4Hoc6DedZBhvHlQ 9RYAXSw1PL25k49+Ww411qc4Df1h4n7cdFuvZVslUx4TSrHcIJEPFoJxi g=; X-IronPort-AV: E=Sophos;i="5.67,249,1566864000"; d="scan'208";a="419366681" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2a-1c1b5cdd.us-west-2.amazon.com) ([10.124.125.6]) by smtp-border-fw-out-6001.iad6.amazon.com with ESMTP; 02 Oct 2019 17:17:10 +0000 Received: from EX13MTAUEA001.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan2.pdx.amazon.com [10.170.41.162]) by email-inbound-relay-2a-1c1b5cdd.us-west-2.amazon.com (Postfix) with ESMTPS id 102CCA1EF0; Wed, 2 Oct 2019 17:17:10 +0000 (UTC) Received: from EX13D10UEE001.ant.amazon.com (10.43.62.201) by EX13MTAUEA001.ant.amazon.com (10.43.61.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Wed, 2 Oct 2019 17:17:00 +0000 Received: from EX13MTAUEE001.ant.amazon.com (10.43.62.200) by EX13D10UEE001.ant.amazon.com (10.43.62.201) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Wed, 2 Oct 2019 17:16:59 +0000 Received: from u9d785c4ba99158.ant.amazon.com (10.125.106.78) by mail-relay.amazon.com (10.43.62.226) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Wed, 2 Oct 2019 17:16:59 +0000 From: Hongyan Xia To: Date: Wed, 2 Oct 2019 18:16:49 +0100 Message-ID: <11d0e9d423772a7ddbd7d239a5029952d8b0c132.1570034362.git.hongyax@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: Bulk Subject: [Xen-devel] [PATCH v3 4/9] 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 Reviewed-by: Jan Beulich --- 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 23066c492e..2b8e192e26 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);