From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761875AbZCZXw2 (ORCPT ); Thu, 26 Mar 2009 19:52:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762169AbZCZXwM (ORCPT ); Thu, 26 Mar 2009 19:52:12 -0400 Received: from ozlabs.org ([203.10.76.45]:60041 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761768AbZCZXwK (ORCPT ); Thu, 26 Mar 2009 19:52:10 -0400 Cc: linux-kernel@vger.kernel.org, Ingo Molnar , jeremy@xensource.com, virtualization@lists.osdl.org, stable@kernel.org To: lguest@ozlabs.org Cc: Ingo Molnar From: Rusty Russell Date: Fri, 27 Mar 2009 10:22:02 +1030 Subject: [PATCH 2/5] lguest: wire up pte_update/pte_update_defer Cc: jeremy@xensource.com Cc: virtualization@lists.osdl.org Cc: stable@kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200903271022.03020.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Impact: intermittent guest segv/crash fix I've been seeing random guest bad address crashes and segmentation faults: bisect led to 4f98a2fee8 (vmscan: split LRU lists into anon & file sets), but that's a red herring. It turns out that lguest never hooked up the pte_update/pte_update_defer calls, so our ptes were not always in sync. After the vmscan commit, the bug became reproducible; now a fsck in a 64MB guest causes reproducible pagetable corruption. Signed-off-by: Rusty Russell Cc: jeremy@xensource.com Cc: virtualization@lists.osdl.org Cc: stable@kernel.org --- arch/x86/lguest/boot.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index 65f0b8a..c3bdf0b 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -475,11 +480,17 @@ static void lguest_write_cr4(unsigned long val) * into a process' address space. We set the entry then tell the Host the * toplevel and address this corresponds to. The Guest uses one pagetable per * process, so we need to tell the Host which one we're changing (mm->pgd). */ +static void lguest_pte_update(struct mm_struct *mm, unsigned long addr, + pte_t *ptep) +{ + lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, ptep->pte_low); +} + static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pteval) { *ptep = pteval; - lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, pteval.pte_low); + lguest_pte_update(mm, addr, ptep); } /* The Guest calls this to set a top-level entry. Again, we set the entry then @@ -1018,6 +1046,8 @@ __init void lguest_init(void) pv_mmu_ops.read_cr3 = lguest_read_cr3; pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu; pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mode; + pv_mmu_ops.pte_update = lguest_pte_update; + pv_mmu_ops.pte_update_defer = lguest_pte_update; #ifdef CONFIG_X86_LOCAL_APIC /* apic read/write intercepts */