kvm: x86: zero EFER on INIT

Not zeroing EFER means that a 32-bit firmware cannot enter paging mode
without clearing EFER.LME first (which it should not know about).
Yang Zhang from Intel confirmed that the manual is wrong and EFER is
cleared to zero on INIT.

Fixes: d28bc9dd
Cc: stable@vger.kernel.org
Cc: Yang Z Zhang <yang.z.zhang@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm.c

@@ -1089,7 +1089,7 @@ static u64 svm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)
 	return target_tsc - tsc;
 }
 
-static void init_vmcb(struct vcpu_svm *svm, bool init_event)
+static void init_vmcb(struct vcpu_svm *svm)
 {
 	struct vmcb_control_area *control = &svm->vmcb->control;
 	struct vmcb_save_area *save = &svm->vmcb->save;
@@ -1160,8 +1160,7 @@ static void init_vmcb(struct vcpu_svm *svm, bool init_event)
 	init_sys_seg(&save->ldtr, SEG_TYPE_LDT);
 	init_sys_seg(&save->tr, SEG_TYPE_BUSY_TSS16);
 
-	if (!init_event)
-		svm_set_efer(&svm->vcpu, 0);
+	svm_set_efer(&svm->vcpu, 0);
 	save->dr6 = 0xffff0ff0;
 	kvm_set_rflags(&svm->vcpu, 2);
 	save->rip = 0x0000fff0;
@@ -1215,7 +1214,7 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 		if (kvm_vcpu_is_reset_bsp(&svm->vcpu))
 			svm->vcpu.arch.apic_base |= MSR_IA32_APICBASE_BSP;
 	}
-	init_vmcb(svm, init_event);
+	init_vmcb(svm);
 
 	kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy);
 	kvm_register_write(vcpu, VCPU_REGS_RDX, eax);
@@ -1271,7 +1270,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 	clear_page(svm->vmcb);
 	svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
 	svm->asid_generation = 0;
-	init_vmcb(svm, false);
+	init_vmcb(svm);
 
 	svm_init_osvw(&svm->vcpu);
 
@@ -1893,7 +1892,7 @@ static int shutdown_interception(struct vcpu_svm *svm)
 	 * so reinitialize it.
 	 */
 	clear_page(svm->vmcb);
-	init_vmcb(svm, false);
+	init_vmcb(svm);
 
 	kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;
 	return 0;

arch/x86/kvm/vmx.c

@@ -4932,8 +4932,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	vmx_set_cr0(vcpu, cr0); /* enter rmode */
 	vmx->vcpu.arch.cr0 = cr0;
 	vmx_set_cr4(vcpu, 0);
-	if (!init_event)
-		vmx_set_efer(vcpu, 0);
+	vmx_set_efer(vcpu, 0);
 	vmx_fpu_activate(vcpu);
 	update_exception_bitmap(vcpu);