From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753791AbcKYIfb (ORCPT ); Fri, 25 Nov 2016 03:35:31 -0500 Received: from mx2.suse.de ([195.135.220.15]:45259 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752744AbcKYIdN (ORCPT ); Fri, 25 Nov 2016 03:33:13 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , Paolo Bonzini , Jiri Slaby Subject: [PATCH 3.12 121/127] KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn() Date: Fri, 25 Nov 2016 09:30:34 +0100 Message-Id: X-Mailer: git-send-email 2.10.2 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ard Biesheuvel 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 85c8555ff07ef09261bd50d603cd4290cff5a8cc upstream. Read-only memory ranges may be backed by the zero page, so avoid misidentifying it a a MMIO pfn. This fixes another issue I identified when testing QEMU+KVM_UEFI, where a read to an uninitialized emulated NOR flash brought in the zero page, but mapped as a read-write device region, because kvm_is_mmio_pfn() misidentifies it as a MMIO pfn due to its PG_reserved bit being set. Signed-off-by: Ard Biesheuvel Fixes: b88657674d39 ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping") Signed-off-by: Paolo Bonzini Signed-off-by: Jiri Slaby --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3351605d2608..e7a1166c3eb4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -104,7 +104,7 @@ static bool largepages_enabled = true; bool kvm_is_mmio_pfn(pfn_t pfn) { if (pfn_valid(pfn)) - return PageReserved(pfn_to_page(pfn)); + return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)); return true; } -- 2.10.2