[PATCH v4 1/4] KVM: x86: Clarify the kvm_run.emulation_failure structure layout

[David Edmondson]

Until more flags for kvm_run.emulation_failure flags are defined, it
is undetermined whether new payload elements corresponding to those
flags will be additive or alternative. As a hint to userspace that an
alternative is possible, wrap the current payload elements in a union.

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: David Edmondson <david.edmondson@xxxxxxxxxx>
---
 include/uapi/linux/kvm.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index d9e4aabcb31a..6c79c1ce3703 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -402,8 +402,12 @@ struct kvm_run {
 			__u32 suberror;
 			__u32 ndata;
 			__u64 flags;
-			__u8  insn_size;
-			__u8  insn_bytes[15];
+			union {
+				struct {
+					__u8  insn_size;
+					__u8  insn_bytes[15];
+				};
+			};
 		} emulation_failure;
 		/* KVM_EXIT_OSI */
 		struct {
-- 
2.30.2