From patchwork Wed Jan 30 21:56:55 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herton Ronaldo Krzesinski X-Patchwork-Id: 217042 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 1EC5F2C029C for ; Thu, 31 Jan 2013 10:12:22 +1100 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1U0feS-0008IM-B9; Wed, 30 Jan 2013 21:57:04 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1U0feO-0008FQ-9S for kernel-team@lists.ubuntu.com; Wed, 30 Jan 2013 21:57:00 +0000 Received: from 189.58.14.63.dynamic.adsl.gvt.net.br ([189.58.14.63] helo=canonical.com) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1U0feM-0004jy-TL; Wed, 30 Jan 2013 21:57:00 +0000 From: Herton Ronaldo Krzesinski To: Matt Wilson Subject: [ 3.5.y.z extended stable ] Patch "xen/grant-table: correctly initialize grant table version 1" has been added to staging queue Date: Wed, 30 Jan 2013 19:56:55 -0200 Message-Id: <1359583015-16821-1-git-send-email-herton.krzesinski@canonical.com> X-Mailer: git-send-email 1.7.9.5 X-Extended-Stable: 3.5 Cc: Ian Campbell , Konrad Rzeszutek Wilk , linux-kernel@vger.kernel.org, xen-devel@lists.xen.org, Annie Li , kernel-team@lists.ubuntu.com X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled xen/grant-table: correctly initialize grant table version 1 to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Herton ------ From f36d45aa5877b4d60952b7270888ddd5925f017f Mon Sep 17 00:00:00 2001 From: Matt Wilson Date: Tue, 15 Jan 2013 13:21:27 +0000 Subject: [PATCH] xen/grant-table: correctly initialize grant table version 1 commit d0b4d64aadb9f4a90669848de9ef3819050a98cd upstream. Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson Reviewed-and-Tested-by: Steven Noonan Acked-by: Ian Campbell Cc: Konrad Rzeszutek Wilk Cc: Annie Li Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Konrad Rzeszutek Wilk [ herton: adjust context ] Signed-off-by: Herton Ronaldo Krzesinski --- drivers/xen/grant-table.c | 48 +++++++++++++++++++++++++++------------------ 1 file changed, 29 insertions(+), 19 deletions(-) -- 1.7.9.5 diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index 0067266..22be735 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -54,10 +54,6 @@ /* External tools reserve first few grant table entries. */ #define NR_RESERVED_ENTRIES 8 #define GNTTAB_LIST_END 0xffffffff -#define GREFS_PER_GRANT_FRAME \ -(grant_table_version == 1 ? \ -(PAGE_SIZE / sizeof(struct grant_entry_v1)) : \ -(PAGE_SIZE / sizeof(union grant_entry_v2))) static grant_ref_t **gnttab_list; static unsigned int nr_grant_frames; @@ -152,6 +148,7 @@ static struct gnttab_ops *gnttab_interface; static grant_status_t *grstatus; static int grant_table_version; +static int grefs_per_grant_frame; static struct gnttab_free_callback *gnttab_free_callback_list; @@ -766,12 +763,14 @@ static int grow_gnttab_list(unsigned int more_frames) unsigned int new_nr_grant_frames, extra_entries, i; unsigned int nr_glist_frames, new_nr_glist_frames; + BUG_ON(grefs_per_grant_frame == 0); + new_nr_grant_frames = nr_grant_frames + more_frames; - extra_entries = more_frames * GREFS_PER_GRANT_FRAME; + extra_entries = more_frames * grefs_per_grant_frame; - nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP; + nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP; new_nr_glist_frames = - (new_nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP; + (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP; for (i = nr_glist_frames; i < new_nr_glist_frames; i++) { gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC); if (!gnttab_list[i]) @@ -779,12 +778,12 @@ static int grow_gnttab_list(unsigned int more_frames) } - for (i = GREFS_PER_GRANT_FRAME * nr_grant_frames; - i < GREFS_PER_GRANT_FRAME * new_nr_grant_frames - 1; i++) + for (i = grefs_per_grant_frame * nr_grant_frames; + i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++) gnttab_entry(i) = i + 1; gnttab_entry(i) = gnttab_free_head; - gnttab_free_head = GREFS_PER_GRANT_FRAME * nr_grant_frames; + gnttab_free_head = grefs_per_grant_frame * nr_grant_frames; gnttab_free_count += extra_entries; nr_grant_frames = new_nr_grant_frames; @@ -904,7 +903,8 @@ EXPORT_SYMBOL_GPL(gnttab_unmap_refs); static unsigned nr_status_frames(unsigned nr_grant_frames) { - return (nr_grant_frames * GREFS_PER_GRANT_FRAME + SPP - 1) / SPP; + BUG_ON(grefs_per_grant_frame == 0); + return (nr_grant_frames * grefs_per_grant_frame + SPP - 1) / SPP; } static int gnttab_map_frames_v1(unsigned long *frames, unsigned int nr_gframes) @@ -1062,6 +1062,7 @@ static void gnttab_request_version(void) rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1); if (rc == 0 && gsv.version == 2) { grant_table_version = 2; + grefs_per_grant_frame = PAGE_SIZE / sizeof(union grant_entry_v2); gnttab_interface = &gnttab_v2_ops; } else if (grant_table_version == 2) { /* @@ -1074,17 +1075,17 @@ static void gnttab_request_version(void) panic("we need grant tables version 2, but only version 1 is available"); } else { grant_table_version = 1; + grefs_per_grant_frame = PAGE_SIZE / sizeof(struct grant_entry_v1); gnttab_interface = &gnttab_v1_ops; } printk(KERN_INFO "Grant tables using version %d layout.\n", grant_table_version); } -int gnttab_resume(void) +static int gnttab_setup(void) { unsigned int max_nr_gframes; - gnttab_request_version(); max_nr_gframes = gnttab_max_grant_frames(); if (max_nr_gframes < nr_grant_frames) return -ENOSYS; @@ -1107,6 +1108,12 @@ int gnttab_resume(void) return 0; } +int gnttab_resume(void) +{ + gnttab_request_version(); + return gnttab_setup(); +} + int gnttab_suspend(void) { gnttab_interface->unmap_frames(); @@ -1118,9 +1125,10 @@ static int gnttab_expand(unsigned int req_entries) int rc; unsigned int cur, extra; + BUG_ON(grefs_per_grant_frame == 0); cur = nr_grant_frames; - extra = ((req_entries + (GREFS_PER_GRANT_FRAME-1)) / - GREFS_PER_GRANT_FRAME); + extra = ((req_entries + (grefs_per_grant_frame-1)) / + grefs_per_grant_frame); if (cur + extra > gnttab_max_grant_frames()) return -ENOSPC; @@ -1138,21 +1146,23 @@ int gnttab_init(void) unsigned int nr_init_grefs; int ret; + gnttab_request_version(); nr_grant_frames = 1; boot_max_nr_grant_frames = __max_nr_grant_frames(); /* Determine the maximum number of frames required for the * grant reference free list on the current hypervisor. */ + BUG_ON(grefs_per_grant_frame == 0); max_nr_glist_frames = (boot_max_nr_grant_frames * - GREFS_PER_GRANT_FRAME / RPP); + grefs_per_grant_frame / RPP); gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *), GFP_KERNEL); if (gnttab_list == NULL) return -ENOMEM; - nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP; + nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP; for (i = 0; i < nr_glist_frames; i++) { gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL); if (gnttab_list[i] == NULL) { @@ -1161,12 +1171,12 @@ int gnttab_init(void) } } - if (gnttab_resume() < 0) { + if (gnttab_setup() < 0) { ret = -ENODEV; goto ini_nomem; } - nr_init_grefs = nr_grant_frames * GREFS_PER_GRANT_FRAME; + nr_init_grefs = nr_grant_frames * grefs_per_grant_frame; for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++) gnttab_entry(i) = i + 1;