Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756394AbcKWBQq (ORCPT ); Tue, 22 Nov 2016 20:16:46 -0500 Received: from mail-pf0-f174.google.com ([209.85.192.174]:34400 "EHLO mail-pf0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756138AbcKWBQK (ORCPT ); Tue, 22 Nov 2016 20:16:10 -0500 From: David Matlack To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, jmattson@google.com, rkrcmar@redhat.com, pbonzini@redhat.com, David Matlack Subject: [PATCH 2/4] KVM: nVMX: fix checks on CR{0,4} during virtual VMX operation Date: Tue, 22 Nov 2016 17:14:38 -0800 Message-Id: <1479863680-117511-3-git-send-email-dmatlack@google.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 In-Reply-To: <1479863680-117511-1-git-send-email-dmatlack@google.com> References: <1479863680-117511-1-git-send-email-dmatlack@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5188 Lines: 144 KVM emulates MSR_IA32_VMX_CR{0,4}_FIXED1 with the value -1ULL, meaning all CR0 and CR4 bits are allowed to be 1 during VMX operation. This does not match real hardware, which disallows the high 32 bits of CR0 to be 1, and disallows reserved bits of CR4 to be 1 (including bits which are defined in the SDM but missing according to CPUID). A guest can induce a VM-entry failure by setting these bits in GUEST_CR0 and GUEST_CR4, despite MSR_IA32_VMX_CR{0,4}_FIXED1 indicating they are valid. Since KVM has allowed all bits to be 1 in CR0 and CR4, the existing checks on these registers do not verify must-be-0 bits. Fix these checks to identify must-be-0 bits according to MSR_IA32_VMX_CR{0,4}_FIXED1. This patch should introduce no change in behavior in KVM, since these MSRs are still -1ULL. Signed-off-by: David Matlack --- arch/x86/kvm/vmx.c | 68 ++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 48 insertions(+), 20 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 6ec3832..a2a5ad8 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -4138,6 +4138,45 @@ static void ept_save_pdptrs(struct kvm_vcpu *vcpu) (unsigned long *)&vcpu->arch.regs_dirty); } +static bool fixed_bits_valid(u64 val, u64 fixed0, u64 fixed1) +{ + return ((val & fixed0) == fixed0) && ((~val & ~fixed1) == ~fixed1); +} + +static bool nested_guest_cr0_valid(struct kvm_vcpu *vcpu, unsigned long val) +{ + u64 fixed0 = to_vmx(vcpu)->nested.nested_vmx_cr0_fixed0; + u64 fixed1 = to_vmx(vcpu)->nested.nested_vmx_cr0_fixed1; + struct vmcs12 *vmcs12 = get_vmcs12(vcpu); + + if (to_vmx(vcpu)->nested.nested_vmx_secondary_ctls_high & + SECONDARY_EXEC_UNRESTRICTED_GUEST && + nested_cpu_has2(vmcs12, SECONDARY_EXEC_UNRESTRICTED_GUEST)) + fixed0 &= ~(X86_CR0_PE | X86_CR0_PG); + + return fixed_bits_valid(val, fixed0, fixed1); +} + +static bool nested_host_cr0_valid(struct kvm_vcpu *vcpu, unsigned long val) +{ + u64 fixed0 = to_vmx(vcpu)->nested.nested_vmx_cr0_fixed0; + u64 fixed1 = to_vmx(vcpu)->nested.nested_vmx_cr0_fixed1; + + return fixed_bits_valid(val, fixed0, fixed1); +} + +static bool nested_cr4_valid(struct kvm_vcpu *vcpu, unsigned long val) +{ + u64 fixed0 = to_vmx(vcpu)->nested.nested_vmx_cr4_fixed0; + u64 fixed1 = to_vmx(vcpu)->nested.nested_vmx_cr4_fixed1; + + return fixed_bits_valid(val, fixed0, fixed1); +} + +/* No difference in the restrictions on guest and host CR4 in VMX operation. */ +#define nested_guest_cr4_valid nested_cr4_valid +#define nested_host_cr4_valid nested_cr4_valid + static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4); static void ept_update_paging_mode_cr0(unsigned long *hw_cr0, @@ -4266,8 +4305,8 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) if (!nested_vmx_allowed(vcpu)) return 1; } - if (to_vmx(vcpu)->nested.vmxon && - ((cr4 & VMXON_CR4_ALWAYSON) != VMXON_CR4_ALWAYSON)) + + if (to_vmx(vcpu)->nested.vmxon && !nested_cr4_valid(vcpu, cr4)) return 1; vcpu->arch.cr4 = cr4; @@ -5886,18 +5925,6 @@ vmx_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall) hypercall[2] = 0xc1; } -static bool nested_cr0_valid(struct kvm_vcpu *vcpu, unsigned long val) -{ - unsigned long always_on = VMXON_CR0_ALWAYSON; - struct vmcs12 *vmcs12 = get_vmcs12(vcpu); - - if (to_vmx(vcpu)->nested.nested_vmx_secondary_ctls_high & - SECONDARY_EXEC_UNRESTRICTED_GUEST && - nested_cpu_has2(vmcs12, SECONDARY_EXEC_UNRESTRICTED_GUEST)) - always_on &= ~(X86_CR0_PE | X86_CR0_PG); - return (val & always_on) == always_on; -} - /* called to set cr0 as appropriate for a mov-to-cr0 exit. */ static int handle_set_cr0(struct kvm_vcpu *vcpu, unsigned long val) { @@ -5916,7 +5943,7 @@ static int handle_set_cr0(struct kvm_vcpu *vcpu, unsigned long val) val = (val & ~vmcs12->cr0_guest_host_mask) | (vmcs12->guest_cr0 & vmcs12->cr0_guest_host_mask); - if (!nested_cr0_valid(vcpu, val)) + if (!nested_guest_cr0_valid(vcpu, val)) return 1; if (kvm_set_cr0(vcpu, val)) @@ -5925,8 +5952,9 @@ static int handle_set_cr0(struct kvm_vcpu *vcpu, unsigned long val) return 0; } else { if (to_vmx(vcpu)->nested.vmxon && - ((val & VMXON_CR0_ALWAYSON) != VMXON_CR0_ALWAYSON)) + !nested_host_cr0_valid(vcpu, val)) return 1; + return kvm_set_cr0(vcpu, val); } } @@ -10472,15 +10500,15 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch) return 1; } - if (((vmcs12->host_cr0 & VMXON_CR0_ALWAYSON) != VMXON_CR0_ALWAYSON) || - ((vmcs12->host_cr4 & VMXON_CR4_ALWAYSON) != VMXON_CR4_ALWAYSON)) { + if (!nested_host_cr0_valid(vcpu, vmcs12->host_cr0) || + !nested_host_cr4_valid(vcpu, vmcs12->host_cr4)) { nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_HOST_STATE_FIELD); return 1; } - if (!nested_cr0_valid(vcpu, vmcs12->guest_cr0) || - ((vmcs12->guest_cr4 & VMXON_CR4_ALWAYSON) != VMXON_CR4_ALWAYSON)) { + if (!nested_guest_cr0_valid(vcpu, vmcs12->guest_cr0) || + !nested_guest_cr4_valid(vcpu, vmcs12->guest_cr4)) { nested_vmx_entry_failure(vcpu, vmcs12, EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT); return 1; -- 2.8.0.rc3.226.g39d4020