From: David Edmondson <david.edmondson@oracle.com>
Date: Mon, 20 Sep 2021 10:37:34 +0000 (+0100)
Subject: KVM: x86: Clarify the kvm_run.emulation_failure structure layout
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=a9d496d8e08ca1eb;p=linux.git

KVM: x86: Clarify the kvm_run.emulation_failure structure layout

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@google.com>
Signed-off-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210920103737.2696756-2-david.edmondson@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 5ca5ffe16cb43..2c8aa8d4dac1f 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -403,8 +403,12 @@ 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 {