static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu)
{
	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
	struct vcpu_vmx *vmx = to_vmx(vcpu);
	struct vmx_msr_entry g, h;
	struct msr_data msr;
	gpa_t gpa;
	u32 i, j;

	vcpu->arch.pat = vmcs_read64(GUEST_IA32_PAT);

	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS) {
		/*
		 * L1's host DR7 is lost if KVM_GUESTDBG_USE_HW_BP is set
		 * as vmcs01.GUEST_DR7 contains a userspace defined value
		 * and vcpu->arch.dr7 is not squirreled away before the
		 * nested VMENTER (not worth adding a variable in nested_vmx).
		 */
		if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
			kvm_set_dr(vcpu, 7, DR7_FIXED_1);
		else
			WARN_ON(kvm_set_dr(vcpu, 7, vmcs_readl(GUEST_DR7)));
	}

	/*
	 * Note that calling vmx_set_{efer,cr0,cr4} is important as they
	 * handle a variety of side effects to KVM's software model.
	 */
	vmx_set_efer(vcpu, nested_vmx_get_vmcs01_guest_efer(vmx));

	vcpu->arch.cr0_guest_owned_bits = X86_CR0_TS;
	vmx_set_cr0(vcpu, vmcs_readl(CR0_READ_SHADOW));

	vcpu->arch.cr4_guest_owned_bits = ~vmcs_readl(CR4_GUEST_HOST_MASK);
	vmx_set_cr4(vcpu, vmcs_readl(CR4_READ_SHADOW));

	nested_ept_uninit_mmu_context(vcpu);
	vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
	__set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);

	/*
	 * Use ept_save_pdptrs(vcpu) to load the MMU's cached PDPTRs
	 * from vmcs01 (if necessary).  The PDPTRs are not loaded on
	 * VMFail, like everything else we just need to ensure our
	 * software model is up-to-date.
	 */
	ept_save_pdptrs(vcpu);

	kvm_mmu_reset_context(vcpu);

	if (cpu_has_vmx_msr_bitmap())
		vmx_update_msr_bitmap(vcpu);

	/*
	 * This nasty bit of open coding is a compromise between blindly
	 * loading L1's MSRs using the exit load lists (incorrect emulation
	 * of VMFail), leaving the nested VM's MSRs in the software model
	 * (incorrect behavior) and snapshotting the modified MSRs (too
	 * expensive since the lists are unbound by hardware).  For each
	 * MSR that was (prematurely) loaded from the nested VMEntry load
	 * list, reload it from the exit load list if it exists and differs
	 * from the guest value.  The intent is to stuff host state as
	 * silently as possible, not to fully process the exit load list.
	 */
	msr.host_initiated = false;
	for (i = 0; i < vmcs12->vm_entry_msr_load_count; i++) {
		gpa = vmcs12->vm_entry_msr_load_addr + (i * sizeof(g));
		if (kvm_vcpu_read_guest(vcpu, gpa, &g, sizeof(g))) {
			pr_debug_ratelimited(
				"%s read MSR index failed (%u, 0x%08llx)\n",
				__func__, i, gpa);
			goto vmabort;
		}

		for (j = 0; j < vmcs12->vm_exit_msr_load_count; j++) {
			gpa = vmcs12->vm_exit_msr_load_addr + (j * sizeof(h));
			if (kvm_vcpu_read_guest(vcpu, gpa, &h, sizeof(h))) {
				pr_debug_ratelimited(
					"%s read MSR failed (%u, 0x%08llx)\n",
					__func__, j, gpa);
				goto vmabort;
			}
			if (h.index != g.index)
				continue;
			if (h.value == g.value)
				break;

			if (nested_vmx_load_msr_check(vcpu, &h)) {
				pr_debug_ratelimited(
					"%s check failed (%u, 0x%x, 0x%x)\n",
					__func__, j, h.index, h.reserved);
				goto vmabort;
			}

			msr.index = h.index;
			msr.data = h.value;
			if (kvm_set_msr(vcpu, &msr)) {
				pr_debug_ratelimited(
					"%s WRMSR failed (%u, 0x%x, 0x%llx)\n",
					__func__, j, h.index, h.value);
				goto vmabort;
			}
		}
	}

	return;

vmabort:
	nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_MSR_FAIL);
}
Unknown