[xen staging] x86emul: always set operand size for AVX-VNNI-INT8 insns

[patchbot@xxxxxxx]

commit d45687cca2450bfebe1dfbddb22f4f03c6fbc9cb
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Aug 23 09:11:15 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Aug 23 09:11:15 2024 +0200

    x86emul: always set operand size for AVX-VNNI-INT8 insns
    
    Unlike for AVX-VNNI-INT16 I failed to notice that op_bytes may still be
    zero when reaching the respective case block: With the ext0f38_table[]
    entries having simd_packed_int, the defaulting at the bottom of
    x86emul_decode() won't set the field to non-zero for F3- or F2-prefixed
    insns.
    
    Fixes: 842acaa743a5 ("x86emul: support AVX-VNNI-INT8")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 3c5f9ce309..eda691868d 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -6075,6 +6075,7 @@ x86_emulate(
     case X86EMUL_OPC_VEX_F2(0x0f38, 0x51): /* vpdpbssds 
[xy]mm/mem,[xy]mm,[xy]mm */
         host_and_vcpu_must_have(avx_vnni_int8);
         generate_exception_if(vex.w, X86_EXC_UD);
+        op_bytes = 16 << vex.l;
         goto simd_0f_ymm;
 
     case X86EMUL_OPC_VEX_66(0x0f38, 0x50): /* vpdpbusd 
[xy]mm/mem,[xy]mm,[xy]mm */
--
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