From: Jan Beulich <jbeulich@suse.com>
Date: Mon, 2 Dec 2024 08:50:14 +0000 (+0100)
Subject: x86emul: MOVBE requires a memory operand
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=4c5d9a01f8fa81417a9c431e9624fb71361ec4f9;p=people%2Fandrewcoop%2Fxen.git

x86emul: MOVBE requires a memory operand

The reg-reg forms should cause #UD; they come into existence only with
APX, where MOVBE also extends BSWAP (for the latter not being "eligible"
to a REX2 prefix).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index 0600df789c..b89d440133 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -6824,6 +6824,7 @@ x86_emulate(
 
     case X86EMUL_OPC(0x0f38, 0xf0): /* movbe m,r */
     case X86EMUL_OPC(0x0f38, 0xf1): /* movbe r,m */
+        generate_exception_if(ea.type != OP_MEM, X86_EXC_UD);
         vcpu_must_have(movbe);
         switch ( op_bytes )
         {