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Commit 384bb783 authored by Jan Kiszka's avatar Jan Kiszka Committed by Gleb Natapov
Browse files

KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER 



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: default avatarJan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent ea8ceb83

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/vmx.c

+40 −0
Original line number Diff line number Diff line
@@ -7558,6 +7558,7 @@ 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))
@@ -7648,6 +7649,45 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch) 
		return 1;

	}



	/*

	 * 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.

arch/x86/kvm/x86.c

+19 −10
Original line number Diff line number Diff line
@@ -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;