Patch "kvm: x86: zero EFER on INIT" has been added to the 4.2-stable tree

This is a note to let you know that I've just added the patch titled

kvm: x86: zero EFER on INIT

to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     kvm-x86-zero-efer-on-init.patch

and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Paolo Bonzini <[email protected]>
Date: Mon, 19 Oct 2015 11:30:19 +0200
Subject: kvm: x86: zero EFER on INIT

From: Paolo Bonzini <[email protected]>

commit 5690891bcec5fcfda38da974ffa5488e36a59811 upstream.

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.

---
 arch/x86/kvm/svm.c |   11 +++++------
 arch/x86/kvm/vmx.c |    3 +--
 2 files changed, 6 insertions(+), 8 deletions(-)

@@ -1085,7 +1085,7 @@ static u64 svm_compute_tsc_offset(struct
 	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;

@@ -1156,8 +1156,7 @@ static void init_vmcb(struct vcpu_svm *s
 	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;

@@ -1211,7 +1210,7 @@ static void svm_vcpu_reset(struct kvm_vc
 		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);

@@ -1267,7 +1266,7 @@ static struct kvm_vcpu *svm_create_vcpu(
 	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);
 

@@ -1889,7 +1888,7 @@ static int shutdown_interception(struct
 	 * so reinitialize it.
 	 */
 	clear_page(svm->vmcb);
-	init_vmcb(svm, false);
+	init_vmcb(svm);
 
 	kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;
 	return 0;

@@ -4780,8 +4780,7 @@ static void vmx_vcpu_reset(struct kvm_vc
 	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);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.2/kvm-x86-set-kvm_req_event-when-updating-irr.patch queue-4.2/mips-kvm-fix-cache-immediate-offset-sign-extension.patch queue-4.2/kvm-x86-handle-smbase-as-physical-address-in-rsm.patch queue-4.2/kvm-x86-obey-kvm_x86_quirk_cd_nw_cleared-in-kvm_set_cr0.patch queue-4.2/mips-kvm-fix-asid-restoration-logic.patch queue-4.2/kvm-x86-zero-efer-on-init.patch queue-4.2/x86-setup-fix-low-identity-map-for-2gb-kernel-range.patch queue-4.2/x86-fpu-fix-get_xsave_addr-behavior-under-virtualization.patch queue-4.2/kvm-x86-allow-rsm-from-64-bit-mode.patch queue-4.2/x86-setup-extend-low-identity-map-to-cover-whole-kernel-range.patch queue-4.2/kvm-x86-add-read_phys-to-x86_emulate_ops.patch queue-4.2/kvm-x86-work-around-infinite-loop-in-microcode-when-ac-is-delivered.patch queue-4.2/mips-kvm-uninit-vcpu-in-vcpu_create-error-path.patch