KVM: nVMX: Ensure that VMCS12 field offsets do not change

Enforce the invariant that existing VMCS12 field offsets must not
change. Experience has shown that without strict enforcement, this
invariant will not be maintained.

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[Changed the code to use BUILD_BUG_ON_MSG instead of better, but GCC 4.6
 requiring _Static_assert. - Radim.]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

arch/x86/kvm/vmx.c

@@ -413,6 +413,162 @@ struct __packed vmcs12 {
 	u16 guest_pml_index;
 };
 
+/*
+ * For save/restore compatibility, the vmcs12 field offsets must not change.
+ */
+#define CHECK_OFFSET(field, loc)				\
+	BUILD_BUG_ON_MSG(offsetof(struct vmcs12, field) != (loc),	\
+		"Offset of " #field " in struct vmcs12 has changed.")
+
+static inline void vmx_check_vmcs12_offsets(void) {
+	CHECK_OFFSET(revision_id, 0);
+	CHECK_OFFSET(abort, 4);
+	CHECK_OFFSET(launch_state, 8);
+	CHECK_OFFSET(io_bitmap_a, 40);
+	CHECK_OFFSET(io_bitmap_b, 48);
+	CHECK_OFFSET(msr_bitmap, 56);
+	CHECK_OFFSET(vm_exit_msr_store_addr, 64);
+	CHECK_OFFSET(vm_exit_msr_load_addr, 72);
+	CHECK_OFFSET(vm_entry_msr_load_addr, 80);
+	CHECK_OFFSET(tsc_offset, 88);
+	CHECK_OFFSET(virtual_apic_page_addr, 96);
+	CHECK_OFFSET(apic_access_addr, 104);
+	CHECK_OFFSET(posted_intr_desc_addr, 112);
+	CHECK_OFFSET(ept_pointer, 120);
+	CHECK_OFFSET(eoi_exit_bitmap0, 128);
+	CHECK_OFFSET(eoi_exit_bitmap1, 136);
+	CHECK_OFFSET(eoi_exit_bitmap2, 144);
+	CHECK_OFFSET(eoi_exit_bitmap3, 152);
+	CHECK_OFFSET(xss_exit_bitmap, 160);
+	CHECK_OFFSET(guest_physical_address, 168);
+	CHECK_OFFSET(vmcs_link_pointer, 176);
+	CHECK_OFFSET(guest_ia32_debugctl, 184);
+	CHECK_OFFSET(guest_ia32_pat, 192);
+	CHECK_OFFSET(guest_ia32_efer, 200);
+	CHECK_OFFSET(guest_ia32_perf_global_ctrl, 208);
+	CHECK_OFFSET(guest_pdptr0, 216);
+	CHECK_OFFSET(guest_pdptr1, 224);
+	CHECK_OFFSET(guest_pdptr2, 232);
+	CHECK_OFFSET(guest_pdptr3, 240);
+	CHECK_OFFSET(guest_bndcfgs, 248);
+	CHECK_OFFSET(host_ia32_pat, 256);
+	CHECK_OFFSET(host_ia32_efer, 264);
+	CHECK_OFFSET(host_ia32_perf_global_ctrl, 272);
+	CHECK_OFFSET(vmread_bitmap, 280);
+	CHECK_OFFSET(vmwrite_bitmap, 288);
+	CHECK_OFFSET(vm_function_control, 296);
+	CHECK_OFFSET(eptp_list_address, 304);
+	CHECK_OFFSET(pml_address, 312);
+	CHECK_OFFSET(cr0_guest_host_mask, 344);
+	CHECK_OFFSET(cr4_guest_host_mask, 352);
+	CHECK_OFFSET(cr0_read_shadow, 360);
+	CHECK_OFFSET(cr4_read_shadow, 368);
+	CHECK_OFFSET(cr3_target_value0, 376);
+	CHECK_OFFSET(cr3_target_value1, 384);
+	CHECK_OFFSET(cr3_target_value2, 392);
+	CHECK_OFFSET(cr3_target_value3, 400);
+	CHECK_OFFSET(exit_qualification, 408);
+	CHECK_OFFSET(guest_linear_address, 416);
+	CHECK_OFFSET(guest_cr0, 424);
+	CHECK_OFFSET(guest_cr3, 432);
+	CHECK_OFFSET(guest_cr4, 440);
+	CHECK_OFFSET(guest_es_base, 448);
+	CHECK_OFFSET(guest_cs_base, 456);
+	CHECK_OFFSET(guest_ss_base, 464);
+	CHECK_OFFSET(guest_ds_base, 472);
+	CHECK_OFFSET(guest_fs_base, 480);
+	CHECK_OFFSET(guest_gs_base, 488);
+	CHECK_OFFSET(guest_ldtr_base, 496);
+	CHECK_OFFSET(guest_tr_base, 504);
+	CHECK_OFFSET(guest_gdtr_base, 512);
+	CHECK_OFFSET(guest_idtr_base, 520);
+	CHECK_OFFSET(guest_dr7, 528);
+	CHECK_OFFSET(guest_rsp, 536);
+	CHECK_OFFSET(guest_rip, 544);
+	CHECK_OFFSET(guest_rflags, 552);
+	CHECK_OFFSET(guest_pending_dbg_exceptions, 560);
+	CHECK_OFFSET(guest_sysenter_esp, 568);
+	CHECK_OFFSET(guest_sysenter_eip, 576);
+	CHECK_OFFSET(host_cr0, 584);
+	CHECK_OFFSET(host_cr3, 592);
+	CHECK_OFFSET(host_cr4, 600);
+	CHECK_OFFSET(host_fs_base, 608);
+	CHECK_OFFSET(host_gs_base, 616);
+	CHECK_OFFSET(host_tr_base, 624);
+	CHECK_OFFSET(host_gdtr_base, 632);
+	CHECK_OFFSET(host_idtr_base, 640);
+	CHECK_OFFSET(host_ia32_sysenter_esp, 648);
+	CHECK_OFFSET(host_ia32_sysenter_eip, 656);
+	CHECK_OFFSET(host_rsp, 664);
+	CHECK_OFFSET(host_rip, 672);
+	CHECK_OFFSET(pin_based_vm_exec_control, 744);
+	CHECK_OFFSET(cpu_based_vm_exec_control, 748);
+	CHECK_OFFSET(exception_bitmap, 752);
+	CHECK_OFFSET(page_fault_error_code_mask, 756);
+	CHECK_OFFSET(page_fault_error_code_match, 760);
+	CHECK_OFFSET(cr3_target_count, 764);
+	CHECK_OFFSET(vm_exit_controls, 768);
+	CHECK_OFFSET(vm_exit_msr_store_count, 772);
+	CHECK_OFFSET(vm_exit_msr_load_count, 776);
+	CHECK_OFFSET(vm_entry_controls, 780);
+	CHECK_OFFSET(vm_entry_msr_load_count, 784);
+	CHECK_OFFSET(vm_entry_intr_info_field, 788);
+	CHECK_OFFSET(vm_entry_exception_error_code, 792);
+	CHECK_OFFSET(vm_entry_instruction_len, 796);
+	CHECK_OFFSET(tpr_threshold, 800);
+	CHECK_OFFSET(secondary_vm_exec_control, 804);
+	CHECK_OFFSET(vm_instruction_error, 808);
+	CHECK_OFFSET(vm_exit_reason, 812);
+	CHECK_OFFSET(vm_exit_intr_info, 816);
+	CHECK_OFFSET(vm_exit_intr_error_code, 820);
+	CHECK_OFFSET(idt_vectoring_info_field, 824);
+	CHECK_OFFSET(idt_vectoring_error_code, 828);
+	CHECK_OFFSET(vm_exit_instruction_len, 832);
+	CHECK_OFFSET(vmx_instruction_info, 836);
+	CHECK_OFFSET(guest_es_limit, 840);
+	CHECK_OFFSET(guest_cs_limit, 844);
+	CHECK_OFFSET(guest_ss_limit, 848);
+	CHECK_OFFSET(guest_ds_limit, 852);
+	CHECK_OFFSET(guest_fs_limit, 856);
+	CHECK_OFFSET(guest_gs_limit, 860);
+	CHECK_OFFSET(guest_ldtr_limit, 864);
+	CHECK_OFFSET(guest_tr_limit, 868);
+	CHECK_OFFSET(guest_gdtr_limit, 872);
+	CHECK_OFFSET(guest_idtr_limit, 876);
+	CHECK_OFFSET(guest_es_ar_bytes, 880);
+	CHECK_OFFSET(guest_cs_ar_bytes, 884);
+	CHECK_OFFSET(guest_ss_ar_bytes, 888);
+	CHECK_OFFSET(guest_ds_ar_bytes, 892);
+	CHECK_OFFSET(guest_fs_ar_bytes, 896);
+	CHECK_OFFSET(guest_gs_ar_bytes, 900);
+	CHECK_OFFSET(guest_ldtr_ar_bytes, 904);
+	CHECK_OFFSET(guest_tr_ar_bytes, 908);
+	CHECK_OFFSET(guest_interruptibility_info, 912);
+	CHECK_OFFSET(guest_activity_state, 916);
+	CHECK_OFFSET(guest_sysenter_cs, 920);
+	CHECK_OFFSET(host_ia32_sysenter_cs, 924);
+	CHECK_OFFSET(vmx_preemption_timer_value, 928);
+	CHECK_OFFSET(virtual_processor_id, 960);
+	CHECK_OFFSET(posted_intr_nv, 962);
+	CHECK_OFFSET(guest_es_selector, 964);
+	CHECK_OFFSET(guest_cs_selector, 966);
+	CHECK_OFFSET(guest_ss_selector, 968);
+	CHECK_OFFSET(guest_ds_selector, 970);
+	CHECK_OFFSET(guest_fs_selector, 972);
+	CHECK_OFFSET(guest_gs_selector, 974);
+	CHECK_OFFSET(guest_ldtr_selector, 976);
+	CHECK_OFFSET(guest_tr_selector, 978);
+	CHECK_OFFSET(guest_intr_status, 980);
+	CHECK_OFFSET(host_es_selector, 982);
+	CHECK_OFFSET(host_cs_selector, 984);
+	CHECK_OFFSET(host_ss_selector, 986);
+	CHECK_OFFSET(host_ds_selector, 988);
+	CHECK_OFFSET(host_fs_selector, 990);
+	CHECK_OFFSET(host_gs_selector, 992);
+	CHECK_OFFSET(host_tr_selector, 994);
+	CHECK_OFFSET(guest_pml_index, 996);
+}
+
 /*
  * VMCS12_REVISION is an arbitrary id that should be changed if the content or
  * layout of struct vmcs12 is changed. MSR_IA32_VMX_BASIC returns this id, and
@@ -12834,6 +12990,7 @@ static int __init vmx_init(void)
 	rcu_assign_pointer(crash_vmclear_loaded_vmcss,
 			   crash_vmclear_local_loaded_vmcss);
 #endif
+	vmx_check_vmcs12_offsets();
 
 	return 0;
 }