Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964938AbXADQJL (ORCPT ); Thu, 4 Jan 2007 11:09:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964980AbXADQJL (ORCPT ); Thu, 4 Jan 2007 11:09:11 -0500 Received: from il.qumranet.com ([62.219.232.206]:47319 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964938AbXADQJK (ORCPT ); Thu, 4 Jan 2007 11:09:10 -0500 Subject: [PATCH 20/33] KVM: MMU: Handle misaligned accesses to write protected guest page tables From: Avi Kivity Date: Thu, 04 Jan 2007 16:09:07 -0000 To: kvm-devel@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, mingo@elte.hu References: <459D21DD.5090506@qumranet.com> In-Reply-To: <459D21DD.5090506@qumranet.com> Message-Id: <20070104160907.2F843250048@il.qumranet.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1970 Lines: 55 A misaligned access affects two shadow ptes instead of just one. Since a misaligned access is unlikely to occur on a real page table, just zap the page out of existence, avoiding further trouble. Signed-off-by: Avi Kivity Index: linux-2.6/drivers/kvm/mmu.c =================================================================== --- linux-2.6.orig/drivers/kvm/mmu.c +++ linux-2.6/drivers/kvm/mmu.c @@ -954,21 +954,36 @@ void kvm_mmu_pre_write(struct kvm_vcpu * gfn_t gfn = gpa >> PAGE_SHIFT; struct kvm_mmu_page *page; struct kvm_mmu_page *child; - struct hlist_node *node; + struct hlist_node *node, *n; struct hlist_head *bucket; unsigned index; u64 *spte; u64 pte; unsigned offset = offset_in_page(gpa); + unsigned pte_size; unsigned page_offset; + unsigned misaligned; int level; pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes); index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES; bucket = &vcpu->kvm->mmu_page_hash[index]; - hlist_for_each_entry(page, node, bucket, hash_link) { + hlist_for_each_entry_safe(page, node, n, bucket, hash_link) { if (page->gfn != gfn || page->role.metaphysical) continue; + pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8; + misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); + if (misaligned) { + /* + * Misaligned accesses are too much trouble to fix + * up; also, they usually indicate a page is not used + * as a page table. + */ + pgprintk("misaligned: gpa %llx bytes %d role %x\n", + gpa, bytes, page->role.word); + kvm_mmu_zap_page(vcpu, page); + continue; + } page_offset = offset; level = page->role.level; if (page->role.glevels == PT32_ROOT_LEVEL) { - 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/