From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755980AbZJAXiM (ORCPT ); Thu, 1 Oct 2009 19:38:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755539AbZJAXiK (ORCPT ); Thu, 1 Oct 2009 19:38:10 -0400 Received: from kroah.org ([198.145.64.141]:42034 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755459AbZJAXiJ (ORCPT ); Thu, 1 Oct 2009 19:38:09 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Thu Oct 1 16:33:20 2009 Message-Id: <20091001233320.400713767@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Thu, 01 Oct 2009 16:31:27 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Marcelo Tosatti , avi@redhat.com Subject: [patch 11/30] KVM: MMU: fix missing locking in alloc_mmu_pages References: <20091001233116.947658905@mini.kroah.org> Content-Disposition: inline; filename=kvm-mmu-fix-missing-locking-in-alloc_mmu_pages.patch In-Reply-To: <20091001233504.GA17709@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.30-stable review patch. If anyone has any objections, please let us know. ------------------ From: Marcelo Tosatti (cherry picked from commit 6a1ac77110ee3e8d8dfdef8442f3b30b3d83e6a2) n_requested_mmu_pages/n_free_mmu_pages are used by kvm_mmu_change_mmu_pages to calculate the number of pages to zap. alloc_mmu_pages, called from the vcpu initialization path, modifies this variables without proper locking, which can result in a negative value in kvm_mmu_change_mmu_pages (say, with cpu hotplug). Signed-off-by: Marcelo Tosatti Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2692,12 +2692,14 @@ static int alloc_mmu_pages(struct kvm_vc ASSERT(vcpu); + spin_lock(&vcpu->kvm->mmu_lock); if (vcpu->kvm->arch.n_requested_mmu_pages) vcpu->kvm->arch.n_free_mmu_pages = vcpu->kvm->arch.n_requested_mmu_pages; else vcpu->kvm->arch.n_free_mmu_pages = vcpu->kvm->arch.n_alloc_mmu_pages; + spin_unlock(&vcpu->kvm->mmu_lock); /* * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64. * Therefore we need to allocate shadow page tables in the first