diff options
| -rw-r--r-- | arch/x86/kvm/vmx/vmcs12.h | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h index 01936013428b..56fd150a6f24 100644 --- a/arch/x86/kvm/vmx/vmcs12.h +++ b/arch/x86/kvm/vmx/vmcs12.h @@ -188,12 +188,13 @@ struct __packed vmcs12 { }; /* - * 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 - * VMPTRLD verifies that the VMCS region that L1 is loading contains this id. + * VMCS12_REVISION is KVM's arbitrary ID for the layout of struct vmcs12. KVM + * enumerates this value to L1 via MSR_IA32_VMX_BASIC, and checks the revision + * ID during nested VMPTRLD to verify that L1 is loading a VMCS that adhere's + * to KVM's virtual CPU definition. * - * IMPORTANT: Changing this value will break save/restore compatibility with - * older kvm releases. + * DO NOT change this value, as it will break save/restore compatibility with + * older KVM releases. */ #define VMCS12_REVISION 0x11e57ed0 @@ -206,7 +207,8 @@ struct __packed vmcs12 { #define VMCS12_SIZE KVM_STATE_NESTED_VMX_VMCS_SIZE /* - * For save/restore compatibility, the vmcs12 field offsets must not change. + * For save/restore compatibility, the vmcs12 field offsets must not change, + * although appending fields and/or filling gaps is obviously allowed. */ #define CHECK_OFFSET(field, loc) \ ASSERT_STRUCT_OFFSET(struct vmcs12, field, loc) |