[PATCH 1/2] KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER

[PATCH 1/2] KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER

[Jan Kiszka]

From: Jan Kiszka <jan.kiszka@siemens.com>

As we may emulate the loading of EFER on VM-entry and VM-exit, implement
the checks that VMX performs on the guest and host values on vmlaunch/
vmresume. Factor out kvm_valid_efer for this purpose which checks for
set reserved bits.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/x86/include/asm/kvm_host.h |    1 +
 arch/x86/kvm/vmx.c              |   38 ++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/x86.c              |   29 +++++++++++++++++++----------
 3 files changed, 58 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b2c7263..28a458f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -805,6 +805,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
 }
 
 void kvm_enable_efer_bits(u64);
+bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
 int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
 int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cc2ba55..0d13b29 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7257,6 +7257,44 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	}
 
 	/*
+	 * If the “load IA32_EFER” VM-entry control is 1, the following checks
+	 * are performed on the field for the IA32_EFER MSR:
+	 * - Bits reserved in the IA32_EFER MSR must be 0.
+	 * - Bit 10 (corresponding to IA32_EFER.LMA) must equal the value of
+	 *   the IA-32e mode guest VM-exit control. It must also be identical
+	 *   to bit 8 (LME) if bit 31 in the CR0 field (corresponding to
+	 *   CR0.PG) is 1.1
+	 */
+	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER &&
+	    (!kvm_valid_efer(vcpu, vmcs12->guest_ia32_efer) ||
+	     !!(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) !=
+	     !!(vmcs12->guest_ia32_efer & EFER_LMA) ||
+	     (vmcs12->guest_cr0 & X86_CR0_PG &&
+	      !!(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) !=
+	      !!(vmcs12->guest_ia32_efer & EFER_LME)))) {
+		nested_vmx_entry_failure(vcpu, vmcs12,
+			EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
+		return 1;
+	}
+
+	/*
+	 * If the load IA32_EFER VM-exit control is 1, bits reserved in the
+	 * IA32_EFER MSR must be 0 in the field for that register. In addition,
+	 * the values of the LMA and LME bits in the field must each be that of
+	 * the host address-space size VM-exit control.
+	 */
+	if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER &&
+	    (!kvm_valid_efer(vcpu, vmcs12->host_ia32_efer) ||
+	     !!(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE) !=
+	     !!(vmcs12->host_ia32_efer & EFER_LMA) ||
+	     !!(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE) !=
+	     !!(vmcs12->host_ia32_efer & EFER_LME))) {
+		nested_vmx_entry_failure(vcpu, vmcs12,
+			EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
+		return 1;
+	}
+
+	/*
 	 * We're finally done with prerequisite checking, and can start with
 	 * the nested entry.
 	 */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index eb9927e..f248a3a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -845,23 +845,17 @@ static const u32 emulated_msrs[] = {
 	MSR_IA32_MCG_CTL,
 };
 
-static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
+bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
-	u64 old_efer = vcpu->arch.efer;
-
 	if (efer & efer_reserved_bits)
-		return 1;
-
-	if (is_paging(vcpu)
-	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
-		return 1;
+		return false;
 
 	if (efer & EFER_FFXSR) {
 		struct kvm_cpuid_entry2 *feat;
 
 		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
 		if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
-			return 1;
+			return false;
 	}
 
 	if (efer & EFER_SVME) {
@@ -869,9 +863,24 @@ static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
 
 		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
 		if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
-			return 1;
+			return false;
 	}
 
+	return true;
+}
+EXPORT_SYMBOL_GPL(kvm_valid_efer);
+
+static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
+{
+	u64 old_efer = vcpu->arch.efer;
+
+	if (!kvm_valid_efer(vcpu, efer))
+		return 1;
+
+	if (is_paging(vcpu)
+	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
+		return 1;
+
 	efer &= ~EFER_LMA;
 	efer |= vcpu->arch.efer & EFER_LMA;
 
-- 
1.7.3.4

[PATCH 2/2] KVM: nVMX: VM_ENTRY/EXIT_LOAD_IA32_EFER overrides EFER.LMA settings

[Jan Kiszka]

From: Jan Kiszka <jan.kiszka@siemens.com>

If we load the complete EFER MSR on entry or exit, EFER.LMA (and LME)
loading is skipped. Their consistency is already checked now before
starting the transition.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/x86/kvm/vmx.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0d13b29..1df3b6f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7135,7 +7135,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 
 	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER)
 		vcpu->arch.efer = vmcs12->guest_ia32_efer;
-	if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
+	else if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
 		vcpu->arch.efer |= (EFER_LMA | EFER_LME);
 	else
 		vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
@@ -7536,7 +7536,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
 {
 	if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER)
 		vcpu->arch.efer = vmcs12->host_ia32_efer;
-	if (vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE)
+	else if (vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE)
 		vcpu->arch.efer |= (EFER_LMA | EFER_LME);
 	else
 		vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
-- 
1.7.3.4

Re: [PATCH 1/2] KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER

[Paolo Bonzini]

Il 14/04/2013 12:44, Jan Kiszka ha scritto:
> +	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER &&
> +	    (!kvm_valid_efer(vcpu, vmcs12->guest_ia32_efer) ||
> +	     !!(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) !=
> +	     !!(vmcs12->guest_ia32_efer & EFER_LMA) ||
> +	     (vmcs12->guest_cr0 & X86_CR0_PG &&
> +	      !!(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) !=
> +	      !!(vmcs12->guest_ia32_efer & EFER_LME)))) {
> +		nested_vmx_entry_failure(vcpu, vmcs12,
> +			EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> +		return 1;
> +	}

    if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER) {
        bool ia32e = (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) != 0;
        if (...) {
        }
    }

Also please put parentheses around the & operator.

The exit tests can similarly extract the host address space size bit to a bool.

Paolo

Re: [PATCH 2/2] KVM: nVMX: VM_ENTRY/EXIT_LOAD_IA32_EFER overrides EFER.LMA settings

[Paolo Bonzini]

Il 14/04/2013 12:44, Jan Kiszka ha scritto:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> If we load the complete EFER MSR on entry or exit, EFER.LMA (and LME)
> loading is skipped. Their consistency is already checked now before
> starting the transition.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  arch/x86/kvm/vmx.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 0d13b29..1df3b6f 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7135,7 +7135,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
>  
>  	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER)
>  		vcpu->arch.efer = vmcs12->guest_ia32_efer;
> -	if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
> +	else if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
>  		vcpu->arch.efer |= (EFER_LMA | EFER_LME);
>  	else
>  		vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
> @@ -7536,7 +7536,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
>  {
>  	if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER)
>  		vcpu->arch.efer = vmcs12->host_ia32_efer;
> -	if (vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE)
> +	else if (vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE)
>  		vcpu->arch.efer |= (EFER_LMA | EFER_LME);
>  	else
>  		vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Re: [PATCH 1/2] KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER

[Marcelo Tosatti]

On Sun, Apr 14, 2013 at 12:44:09PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> As we may emulate the loading of EFER on VM-entry and VM-exit, implement
> the checks that VMX performs on the guest and host values on vmlaunch/
> vmresume. Factor out kvm_valid_efer for this purpose which checks for
> set reserved bits.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  arch/x86/include/asm/kvm_host.h |    1 +
>  arch/x86/kvm/vmx.c              |   38 ++++++++++++++++++++++++++++++++++++++
>  arch/x86/kvm/x86.c              |   29 +++++++++++++++++++----------
>  3 files changed, 58 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index b2c7263..28a458f 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -805,6 +805,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
>  }
>  
>  void kvm_enable_efer_bits(u64);
> +bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
>  int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
>  int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
>  
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index cc2ba55..0d13b29 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7257,6 +7257,44 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>  	}
>  
>  	/*
> +	 * If the “load IA32_EFER” VM-entry control is 1, the following checks
> +	 * are performed on the field for the IA32_EFER MSR:
> +	 * - Bits reserved in the IA32_EFER MSR must be 0.
> +	 * - Bit 10 (corresponding to IA32_EFER.LMA) must equal the value of
> +	 *   the IA-32e mode guest VM-exit control. It must also be identical
> +	 *   to bit 8 (LME) if bit 31 in the CR0 field (corresponding to
> +	 *   CR0.PG) is 1.1
			^^^

Typo?

[PATCH v2 1/2] KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER

[Jan Kiszka]

As we may emulate the loading of EFER on VM-entry and VM-exit, implement
the checks that VMX performs on the guest and host values on vmlaunch/
vmresume. Factor out kvm_valid_efer for this purpose which checks for
set reserved bits.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Changes in v2:
 - refactored if clauses as requested by Paolo
 - fixed typo in comment found my Marcelo

 arch/x86/include/asm/kvm_host.h |    1 +
 arch/x86/kvm/vmx.c              |   40 +++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/x86.c              |   29 ++++++++++++++++++---------
 3 files changed, 60 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 599f98b..18635ae 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -809,6 +809,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
 }
 
 void kvm_enable_efer_bits(u64);
+bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
 int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
 int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 19aebc7..e3b951f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7327,6 +7327,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	int cpu;
 	struct loaded_vmcs *vmcs02;
+	bool ia32e;
 
 	if (!nested_vmx_check_permission(vcpu) ||
 	    !nested_vmx_check_vmcs12(vcpu))
@@ -7415,6 +7416,45 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	}
 
 	/*
+	 * If the “load IA32_EFER” VM-entry control is 1, the following checks
+	 * are performed on the field for the IA32_EFER MSR:
+	 * - Bits reserved in the IA32_EFER MSR must be 0.
+	 * - Bit 10 (corresponding to IA32_EFER.LMA) must equal the value of
+	 *   the IA-32e mode guest VM-exit control. It must also be identical
+	 *   to bit 8 (LME) if bit 31 in the CR0 field (corresponding to
+	 *   CR0.PG) is 1.
+	 */
+	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER) {
+		ia32e = (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) != 0;
+		if (!kvm_valid_efer(vcpu, vmcs12->guest_ia32_efer) ||
+		    ia32e != !!(vmcs12->guest_ia32_efer & EFER_LMA) ||
+		    ((vmcs12->guest_cr0 & X86_CR0_PG) &&
+		     ia32e != !!(vmcs12->guest_ia32_efer & EFER_LME))) {
+			nested_vmx_entry_failure(vcpu, vmcs12,
+				EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
+			return 1;
+		}
+	}
+
+	/*
+	 * If the load IA32_EFER VM-exit control is 1, bits reserved in the
+	 * IA32_EFER MSR must be 0 in the field for that register. In addition,
+	 * the values of the LMA and LME bits in the field must each be that of
+	 * the host address-space size VM-exit control.
+	 */
+	if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER) {
+		ia32e = (vmcs12->vm_exit_controls &
+			 VM_EXIT_HOST_ADDR_SPACE_SIZE) != 0;
+		if (!kvm_valid_efer(vcpu, vmcs12->host_ia32_efer) ||
+		    ia32e != !!(vmcs12->host_ia32_efer & EFER_LMA) ||
+		    ia32e != !!(vmcs12->host_ia32_efer & EFER_LME)) {
+			nested_vmx_entry_failure(vcpu, vmcs12,
+				EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
+			return 1;
+		}
+	}
+
+	/*
 	 * We're finally done with prerequisite checking, and can start with
 	 * the nested entry.
 	 */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 50e2e10..482784d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -845,23 +845,17 @@ static const u32 emulated_msrs[] = {
 	MSR_IA32_MCG_CTL,
 };
 
-static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
+bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
-	u64 old_efer = vcpu->arch.efer;
-
 	if (efer & efer_reserved_bits)
-		return 1;
-
-	if (is_paging(vcpu)
-	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
-		return 1;
+		return false;
 
 	if (efer & EFER_FFXSR) {
 		struct kvm_cpuid_entry2 *feat;
 
 		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
 		if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
-			return 1;
+			return false;
 	}
 
 	if (efer & EFER_SVME) {
@@ -869,9 +863,24 @@ static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
 
 		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
 		if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
-			return 1;
+			return false;
 	}
 
+	return true;
+}
+EXPORT_SYMBOL_GPL(kvm_valid_efer);
+
+static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
+{
+	u64 old_efer = vcpu->arch.efer;
+
+	if (!kvm_valid_efer(vcpu, efer))
+		return 1;
+
+	if (is_paging(vcpu)
+	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
+		return 1;
+
 	efer &= ~EFER_LMA;
 	efer |= vcpu->arch.efer & EFER_LMA;
 
-- 
1.7.3.4

Re: [PATCH v2 1/2] KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER

[Paolo Bonzini]

Il 20/04/2013 10:52, Jan Kiszka ha scritto:
> As we may emulate the loading of EFER on VM-entry and VM-exit, implement
> the checks that VMX performs on the guest and host values on vmlaunch/
> vmresume. Factor out kvm_valid_efer for this purpose which checks for
> set reserved bits.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> Changes in v2:
>  - refactored if clauses as requested by Paolo
>  - fixed typo in comment found my Marcelo
> 
>  arch/x86/include/asm/kvm_host.h |    1 +
>  arch/x86/kvm/vmx.c              |   40 +++++++++++++++++++++++++++++++++++++++
>  arch/x86/kvm/x86.c              |   29 ++++++++++++++++++---------
>  3 files changed, 60 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 599f98b..18635ae 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -809,6 +809,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
>  }
>  
>  void kvm_enable_efer_bits(u64);
> +bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
>  int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
>  int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
>  
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 19aebc7..e3b951f 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7327,6 +7327,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>  	int cpu;
>  	struct loaded_vmcs *vmcs02;
> +	bool ia32e;
>  
>  	if (!nested_vmx_check_permission(vcpu) ||
>  	    !nested_vmx_check_vmcs12(vcpu))
> @@ -7415,6 +7416,45 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>  	}
>  
>  	/*
> +	 * If the “load IA32_EFER” VM-entry control is 1, the following checks
> +	 * are performed on the field for the IA32_EFER MSR:
> +	 * - Bits reserved in the IA32_EFER MSR must be 0.
> +	 * - Bit 10 (corresponding to IA32_EFER.LMA) must equal the value of
> +	 *   the IA-32e mode guest VM-exit control. It must also be identical
> +	 *   to bit 8 (LME) if bit 31 in the CR0 field (corresponding to
> +	 *   CR0.PG) is 1.
> +	 */
> +	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER) {
> +		ia32e = (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) != 0;
> +		if (!kvm_valid_efer(vcpu, vmcs12->guest_ia32_efer) ||
> +		    ia32e != !!(vmcs12->guest_ia32_efer & EFER_LMA) ||
> +		    ((vmcs12->guest_cr0 & X86_CR0_PG) &&
> +		     ia32e != !!(vmcs12->guest_ia32_efer & EFER_LME))) {
> +			nested_vmx_entry_failure(vcpu, vmcs12,
> +				EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> +			return 1;
> +		}
> +	}
> +
> +	/*
> +	 * If the load IA32_EFER VM-exit control is 1, bits reserved in the
> +	 * IA32_EFER MSR must be 0 in the field for that register. In addition,
> +	 * the values of the LMA and LME bits in the field must each be that of
> +	 * the host address-space size VM-exit control.
> +	 */
> +	if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER) {
> +		ia32e = (vmcs12->vm_exit_controls &
> +			 VM_EXIT_HOST_ADDR_SPACE_SIZE) != 0;
> +		if (!kvm_valid_efer(vcpu, vmcs12->host_ia32_efer) ||
> +		    ia32e != !!(vmcs12->host_ia32_efer & EFER_LMA) ||
> +		    ia32e != !!(vmcs12->host_ia32_efer & EFER_LME)) {
> +			nested_vmx_entry_failure(vcpu, vmcs12,
> +				EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> +			return 1;
> +		}
> +	}

Looks good, difficult to do better with C's operator precedence rules.

Paolo

> +	/*
>  	 * We're finally done with prerequisite checking, and can start with
>  	 * the nested entry.
>  	 */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 50e2e10..482784d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -845,23 +845,17 @@ static const u32 emulated_msrs[] = {
>  	MSR_IA32_MCG_CTL,
>  };
>  
> -static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
> +bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
>  {
> -	u64 old_efer = vcpu->arch.efer;
> -
>  	if (efer & efer_reserved_bits)
> -		return 1;
> -
> -	if (is_paging(vcpu)
> -	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
> -		return 1;
> +		return false;
>  
>  	if (efer & EFER_FFXSR) {
>  		struct kvm_cpuid_entry2 *feat;
>  
>  		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
>  		if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
> -			return 1;
> +			return false;
>  	}
>  
>  	if (efer & EFER_SVME) {
> @@ -869,9 +863,24 @@ static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
>  
>  		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
>  		if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
> -			return 1;
> +			return false;
>  	}
>  
> +	return true;
> +}
> +EXPORT_SYMBOL_GPL(kvm_valid_efer);
> +
> +static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
> +{
> +	u64 old_efer = vcpu->arch.efer;
> +
> +	if (!kvm_valid_efer(vcpu, efer))
> +		return 1;
> +
> +	if (is_paging(vcpu)
> +	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
> +		return 1;
> +
>  	efer &= ~EFER_LMA;
>  	efer |= vcpu->arch.efer & EFER_LMA;
>  
> 

Re: [PATCH 1/2] KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER

[Gleb Natapov]

On Sun, Apr 14, 2013 at 12:44:09PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> As we may emulate the loading of EFER on VM-entry and VM-exit, implement
> the checks that VMX performs on the guest and host values on vmlaunch/
> vmresume. Factor out kvm_valid_efer for this purpose which checks for
> set reserved bits.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Applied v2 of 1/2 and 2/2.

> ---
>  arch/x86/include/asm/kvm_host.h |    1 +
>  arch/x86/kvm/vmx.c              |   38 ++++++++++++++++++++++++++++++++++++++
>  arch/x86/kvm/x86.c              |   29 +++++++++++++++++++----------
>  3 files changed, 58 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index b2c7263..28a458f 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -805,6 +805,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
>  }
>  
>  void kvm_enable_efer_bits(u64);
> +bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
>  int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
>  int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
>  
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index cc2ba55..0d13b29 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7257,6 +7257,44 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>  	}
>  
>  	/*
> +	 * If the “load IA32_EFER” VM-entry control is 1, the following checks
> +	 * are performed on the field for the IA32_EFER MSR:
> +	 * - Bits reserved in the IA32_EFER MSR must be 0.
> +	 * - Bit 10 (corresponding to IA32_EFER.LMA) must equal the value of
> +	 *   the IA-32e mode guest VM-exit control. It must also be identical
> +	 *   to bit 8 (LME) if bit 31 in the CR0 field (corresponding to
> +	 *   CR0.PG) is 1.1
> +	 */
> +	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER &&
> +	    (!kvm_valid_efer(vcpu, vmcs12->guest_ia32_efer) ||
> +	     !!(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) !=
> +	     !!(vmcs12->guest_ia32_efer & EFER_LMA) ||
> +	     (vmcs12->guest_cr0 & X86_CR0_PG &&
> +	      !!(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) !=
> +	      !!(vmcs12->guest_ia32_efer & EFER_LME)))) {
> +		nested_vmx_entry_failure(vcpu, vmcs12,
> +			EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> +		return 1;
> +	}
> +
> +	/*
> +	 * If the load IA32_EFER VM-exit control is 1, bits reserved in the
> +	 * IA32_EFER MSR must be 0 in the field for that register. In addition,
> +	 * the values of the LMA and LME bits in the field must each be that of
> +	 * the host address-space size VM-exit control.
> +	 */
> +	if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER &&
> +	    (!kvm_valid_efer(vcpu, vmcs12->host_ia32_efer) ||
> +	     !!(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE) !=
> +	     !!(vmcs12->host_ia32_efer & EFER_LMA) ||
> +	     !!(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE) !=
> +	     !!(vmcs12->host_ia32_efer & EFER_LME))) {
> +		nested_vmx_entry_failure(vcpu, vmcs12,
> +			EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> +		return 1;
> +	}
> +
> +	/*
>  	 * We're finally done with prerequisite checking, and can start with
>  	 * the nested entry.
>  	 */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index eb9927e..f248a3a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -845,23 +845,17 @@ static const u32 emulated_msrs[] = {
>  	MSR_IA32_MCG_CTL,
>  };
>  
> -static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
> +bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
>  {
> -	u64 old_efer = vcpu->arch.efer;
> -
>  	if (efer & efer_reserved_bits)
> -		return 1;
> -
> -	if (is_paging(vcpu)
> -	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
> -		return 1;
> +		return false;
>  
>  	if (efer & EFER_FFXSR) {
>  		struct kvm_cpuid_entry2 *feat;
>  
>  		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
>  		if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
> -			return 1;
> +			return false;
>  	}
>  
>  	if (efer & EFER_SVME) {
> @@ -869,9 +863,24 @@ static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
>  
>  		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
>  		if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
> -			return 1;
> +			return false;
>  	}
>  
> +	return true;
> +}
> +EXPORT_SYMBOL_GPL(kvm_valid_efer);
> +
> +static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
> +{
> +	u64 old_efer = vcpu->arch.efer;
> +
> +	if (!kvm_valid_efer(vcpu, efer))
> +		return 1;
> +
> +	if (is_paging(vcpu)
> +	    && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
> +		return 1;
> +
>  	efer &= ~EFER_LMA;
>  	efer |= vcpu->arch.efer & EFER_LMA;
>  
> -- 
> 1.7.3.4

--
			Gleb.