From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89A02C07520 for ; Thu, 13 Sep 2018 13:49:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4FEA420854 for ; Thu, 13 Sep 2018 13:49:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4FEA420854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730579AbeIMS6i (ORCPT ); Thu, 13 Sep 2018 14:58:38 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:32984 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728688AbeIMS6h (ORCPT ); Thu, 13 Sep 2018 14:58:37 -0400 Received: from localhost (ip-213-127-77-73.ip.prioritytelecom.net [213.127.77.73]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id C6056CFE; Thu, 13 Sep 2018 13:49:02 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Junaid Shahid , Paolo Bonzini Subject: [PATCH 4.14 110/115] kvm: x86: Set highest physical address bits in non-present/reserved SPTEs Date: Thu, 13 Sep 2018 15:32:10 +0200 Message-Id: <20180913131830.061070299@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180913131823.327472833@linuxfoundation.org> References: <20180913131823.327472833@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Junaid Shahid commit 28a1f3ac1d0c8558ee4453d9634dad891a6e922e upstream. Always set the 5 upper-most supported physical address bits to 1 for SPTEs that are marked as non-present or reserved, to make them unusable for L1TF attacks from the guest. Currently, this just applies to MMIO SPTEs. (We do not need to mark PTEs that are completely 0 as physical page 0 is already reserved.) This allows mitigation of L1TF without disabling hyper-threading by using shadow paging mode instead of EPT. Signed-off-by: Junaid Shahid Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu.c | 43 ++++++++++++++++++++++++++++++++++++++----- arch/x86/kvm/x86.c | 8 ++++++-- 2 files changed, 44 insertions(+), 7 deletions(-) --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -220,6 +220,17 @@ static const u64 shadow_acc_track_saved_ PT64_EPT_EXECUTABLE_MASK; static const u64 shadow_acc_track_saved_bits_shift = PT64_SECOND_AVAIL_BITS_SHIFT; +/* + * This mask must be set on all non-zero Non-Present or Reserved SPTEs in order + * to guard against L1TF attacks. + */ +static u64 __read_mostly shadow_nonpresent_or_rsvd_mask; + +/* + * The number of high-order 1 bits to use in the mask above. + */ +static const u64 shadow_nonpresent_or_rsvd_mask_len = 5; + static void mmu_spte_set(u64 *sptep, u64 spte); static void mmu_free_roots(struct kvm_vcpu *vcpu); @@ -308,9 +319,13 @@ static void mark_mmio_spte(struct kvm_vc { unsigned int gen = kvm_current_mmio_generation(vcpu); u64 mask = generation_mmio_spte_mask(gen); + u64 gpa = gfn << PAGE_SHIFT; access &= ACC_WRITE_MASK | ACC_USER_MASK; - mask |= shadow_mmio_value | access | gfn << PAGE_SHIFT; + mask |= shadow_mmio_value | access; + mask |= gpa | shadow_nonpresent_or_rsvd_mask; + mask |= (gpa & shadow_nonpresent_or_rsvd_mask) + << shadow_nonpresent_or_rsvd_mask_len; trace_mark_mmio_spte(sptep, gfn, access, gen); mmu_spte_set(sptep, mask); @@ -323,8 +338,14 @@ static bool is_mmio_spte(u64 spte) static gfn_t get_mmio_spte_gfn(u64 spte) { - u64 mask = generation_mmio_spte_mask(MMIO_GEN_MASK) | shadow_mmio_mask; - return (spte & ~mask) >> PAGE_SHIFT; + u64 mask = generation_mmio_spte_mask(MMIO_GEN_MASK) | shadow_mmio_mask | + shadow_nonpresent_or_rsvd_mask; + u64 gpa = spte & ~mask; + + gpa |= (spte >> shadow_nonpresent_or_rsvd_mask_len) + & shadow_nonpresent_or_rsvd_mask; + + return gpa >> PAGE_SHIFT; } static unsigned get_mmio_spte_access(u64 spte) @@ -381,7 +402,7 @@ void kvm_mmu_set_mask_ptes(u64 user_mask } EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes); -void kvm_mmu_clear_all_pte_masks(void) +static void kvm_mmu_reset_all_pte_masks(void) { shadow_user_mask = 0; shadow_accessed_mask = 0; @@ -391,6 +412,18 @@ void kvm_mmu_clear_all_pte_masks(void) shadow_mmio_mask = 0; shadow_present_mask = 0; shadow_acc_track_mask = 0; + + /* + * If the CPU has 46 or less physical address bits, then set an + * appropriate mask to guard against L1TF attacks. Otherwise, it is + * assumed that the CPU is not vulnerable to L1TF. + */ + if (boot_cpu_data.x86_phys_bits < + 52 - shadow_nonpresent_or_rsvd_mask_len) + shadow_nonpresent_or_rsvd_mask = + rsvd_bits(boot_cpu_data.x86_phys_bits - + shadow_nonpresent_or_rsvd_mask_len, + boot_cpu_data.x86_phys_bits - 1); } static int is_cpuid_PSE36(void) @@ -5473,7 +5506,7 @@ static void mmu_destroy_caches(void) int kvm_mmu_module_init(void) { - kvm_mmu_clear_all_pte_masks(); + kvm_mmu_reset_all_pte_masks(); pte_list_desc_cache = kmem_cache_create("pte_list_desc", sizeof(struct pte_list_desc), --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6194,8 +6194,12 @@ static void kvm_set_mmio_spte_mask(void) * Set the reserved bits and the present bit of an paging-structure * entry to generate page fault with PFER.RSV = 1. */ - /* Mask the reserved physical address bits. */ - mask = rsvd_bits(maxphyaddr, 51); + + /* + * Mask the uppermost physical address bit, which would be reserved as + * long as the supported physical address width is less than 52. + */ + mask = 1ull << 51; /* Set the present bit. */ mask |= 1ull;