Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757110AbZJBBtL (ORCPT ); Thu, 1 Oct 2009 21:49:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757054AbZJBBtI (ORCPT ); Thu, 1 Oct 2009 21:49:08 -0400 Received: from kroah.org ([198.145.64.141]:33268 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756412AbZJBBdc (ORCPT ); Thu, 1 Oct 2009 21:33:32 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Thu Oct 1 18:24:18 2009 Message-Id: <20091002012418.302580674@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Thu, 01 Oct 2009 18:17:03 -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: [075/136] KVM: MMU: fix missing locking in alloc_mmu_pages References: <20091002011548.335611824@mini.kroah.org> Content-Disposition: inline; filename=kvm-mmu-fix-missing-locking-in-alloc_mmu_pages.patch In-Reply-To: <20091002012911.GA18542@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1512 Lines: 36 2.6.31-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 @@ -2713,12 +2713,14 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/