From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762017AbZEFV5X (ORCPT ); Wed, 6 May 2009 17:57:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761407AbZEFVy1 (ORCPT ); Wed, 6 May 2009 17:54:27 -0400 Received: from kroah.org ([198.145.64.141]:56953 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760095AbZEFVyY (ORCPT ); Wed, 6 May 2009 17:54:24 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Wed May 6 14:47:56 2009 Message-Id: <20090506214756.305441008@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Wed, 06 May 2009 14:45:36 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org, jejb@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Avi Kivity , Chris Wright Subject: [patch 08/58] KVM: MMU: Fix off-by-one calculating large page count References: <20090506214528.660389067@mini.kroah.org> Content-Disposition: inline; filename=kvm-mmu-fix-off-by-one-calculating-large-page-count.patch In-Reply-To: <20090506215017.GA21981@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.29-stable review patch. If anyone has any objections, please let us know. ------------------ From: Avi Kivity upstream commit: 99894a799f09cf9e28296bb16e75bd5830fd2c4e The large page initialization code concludes there are two large pages spanned by a slot covering 1 (small) page starting at gfn 1. This is incorrect, and also results in incorrect write_count initialization in some cases (base = 1, npages = 513 for example). Cc: stable@kernel.org Signed-off-by: Avi Kivity Signed-off-by: Chris Wright --- virt/kvm/kvm_main.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -964,6 +964,7 @@ int __kvm_set_memory_region(struct kvm * int r; gfn_t base_gfn; unsigned long npages; + int largepages; unsigned long i; struct kvm_memory_slot *memslot; struct kvm_memory_slot old, new; @@ -1039,11 +1040,8 @@ int __kvm_set_memory_region(struct kvm * new.userspace_addr = 0; } if (npages && !new.lpage_info) { - int largepages = npages / KVM_PAGES_PER_HPAGE; - if (npages % KVM_PAGES_PER_HPAGE) - largepages++; - if (base_gfn % KVM_PAGES_PER_HPAGE) - largepages++; + largepages = 1 + (base_gfn + npages - 1) / KVM_PAGES_PER_HPAGE; + largepages -= base_gfn / KVM_PAGES_PER_HPAGE; new.lpage_info = vmalloc(largepages * sizeof(*new.lpage_info));