Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754634AbbEKPDk (ORCPT ); Mon, 11 May 2015 11:03:40 -0400 Received: from mga02.intel.com ([134.134.136.20]:11922 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751373AbbEKO7G (ORCPT ); Mon, 11 May 2015 10:59:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,407,1427785200"; d="scan'208";a="569526182" From: Xiao Guangrong To: pbonzini@redhat.com Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiao Guangrong Subject: [PATCH 1/2] KVM: MMU: fix SMAP virtualization Date: Mon, 11 May 2015 22:55:21 +0800 Message-Id: <1431356122-8500-1-git-send-email-guangrong.xiao@linux.intel.com> X-Mailer: git-send-email 2.1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4674 Lines: 134 KVM may turn a user page to a kernel page when kernel writes a readonly user page if CR0.WP = 1. This shadow page entry will be reused after SMAP is enabled so that kernel is allowed to access this user page Fix it by setting SMAP && !CR0.WP into shadow page's role and reset mmu once CR4.SMAP is updated Signed-off-by: Xiao Guangrong --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.c | 16 ++++++++++++---- arch/x86/kvm/mmu.h | 2 -- arch/x86/kvm/x86.c | 8 +++----- 4 files changed, 16 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 8b661d1..bbb8f4e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -207,6 +207,7 @@ union kvm_mmu_page_role { unsigned nxe:1; unsigned cr0_wp:1; unsigned smep_andnot_wp:1; + unsigned smap_andnot_wp:1; }; }; diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 3711095..b78e83f 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3737,8 +3737,8 @@ static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu, } } -void update_permission_bitmask(struct kvm_vcpu *vcpu, - struct kvm_mmu *mmu, bool ept) +static void update_permission_bitmask(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu, bool ept) { unsigned bit, byte, pfec; u8 map; @@ -3919,6 +3919,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu) { bool smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP); + bool smap = kvm_read_cr4_bits(vcpu, X86_CR4_SMAP); struct kvm_mmu *context = &vcpu->arch.mmu; MMU_WARN_ON(VALID_PAGE(context->root_hpa)); @@ -3937,6 +3938,8 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu) context->base_role.cr0_wp = is_write_protection(vcpu); context->base_role.smep_andnot_wp = smep && !is_write_protection(vcpu); + context->base_role.smap_andnot_wp + = smap && !is_write_protection(vcpu); } EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu); @@ -4208,12 +4211,18 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, int bytes) { gfn_t gfn = gpa >> PAGE_SHIFT; - union kvm_mmu_page_role mask = { .word = 0 }; struct kvm_mmu_page *sp; LIST_HEAD(invalid_list); u64 entry, gentry, *spte; int npte; bool remote_flush, local_flush, zap_page; + union kvm_mmu_page_role mask = (union kvm_mmu_page_role) { + .cr0_wp = 1, + .cr4_pae = 1, + .nxe = 1, + .smep_andnot_wp = 1, + .smap_andnot_wp = 1, + }; /* * If we don't have indirect shadow pages, it means no page is @@ -4239,7 +4248,6 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, ++vcpu->kvm->stat.mmu_pte_write; kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE); - mask.cr0_wp = mask.cr4_pae = mask.nxe = mask.smep_andnot_wp = 1; for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) { if (detect_write_misaligned(sp, gpa, bytes) || detect_write_flooding(sp)) { diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 06eb2fc..0ada65e 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -71,8 +71,6 @@ enum { int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct); void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu); void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly); -void update_permission_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, - bool ept); static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index cdccbe1..cde5d61 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -702,8 +702,9 @@ EXPORT_SYMBOL_GPL(kvm_set_xcr); int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { unsigned long old_cr4 = kvm_read_cr4(vcpu); - unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | - X86_CR4_PAE | X86_CR4_SMEP; + unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE | + X86_CR4_SMEP | X86_CR4_SMAP; + if (cr4 & CR4_RESERVED_BITS) return 1; @@ -744,9 +745,6 @@ int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) (!(cr4 & X86_CR4_PCIDE) && (old_cr4 & X86_CR4_PCIDE))) kvm_mmu_reset_context(vcpu); - if ((cr4 ^ old_cr4) & X86_CR4_SMAP) - update_permission_bitmask(vcpu, vcpu->arch.walk_mmu, false); - if ((cr4 ^ old_cr4) & X86_CR4_OSXSAVE) kvm_update_cpuid(vcpu); -- 2.1.0 -- 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/