From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752282AbbKOCEv (ORCPT ); Sat, 14 Nov 2015 21:04:51 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35126 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751914AbbKOCEs (ORCPT ); Sat, 14 Nov 2015 21:04:48 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org Date: Sun, 15 Nov 2015 01:45:45 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 01/60] Revert "KVM: MMU: fix validation of mmio page fault" In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.247 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.73-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings This reverts commit 41e3025eacd6daafc40c3e7850fbcabc8b847805, which was commit 6f691251c0350ac52a007c54bf3ef62e9d8cdc5e upstream. The fix is only needed after commit f8f559422b6c ("KVM: MMU: fast invalidate all mmio sptes"), included in Linux 3.11. Signed-off-by: Ben Hutchings --- arch/x86/kvm/mmu.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index cac7b2b..4a949c7 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -326,6 +326,12 @@ static u64 __get_spte_lockless(u64 *sptep) { return ACCESS_ONCE(*sptep); } + +static bool __check_direct_spte_mmio_pf(u64 spte) +{ + /* It is valid if the spte is zapped. */ + return spte == 0ull; +} #else union split_spte { struct { @@ -430,6 +436,23 @@ retry: return spte.spte; } + +static bool __check_direct_spte_mmio_pf(u64 spte) +{ + union split_spte sspte = (union split_spte)spte; + u32 high_mmio_mask = shadow_mmio_mask >> 32; + + /* It is valid if the spte is zapped. */ + if (spte == 0ull) + return true; + + /* It is valid if the spte is being zapped. */ + if (sspte.spte_low == 0ull && + (sspte.spte_high & high_mmio_mask) == high_mmio_mask) + return true; + + return false; +} #endif static bool spte_has_volatile_bits(u64 spte) @@ -2872,6 +2895,21 @@ static bool quickly_check_mmio_pf(struct kvm_vcpu *vcpu, u64 addr, bool direct) return vcpu_match_mmio_gva(vcpu, addr); } + +/* + * On direct hosts, the last spte is only allows two states + * for mmio page fault: + * - It is the mmio spte + * - It is zapped or it is being zapped. + * + * This function completely checks the spte when the last spte + * is not the mmio spte. + */ +static bool check_direct_spte_mmio_pf(u64 spte) +{ + return __check_direct_spte_mmio_pf(spte); +} + static u64 walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr) { struct kvm_shadow_walk_iterator iterator; @@ -2913,6 +2951,13 @@ int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct) } /* + * It's ok if the gva is remapped by other cpus on shadow guest, + * it's a BUG if the gfn is not a mmio page. + */ + if (direct && !check_direct_spte_mmio_pf(spte)) + return -1; + + /* * If the page table is zapped by other cpus, let CPU fault again on * the address. */