[PATCH v2] x86emul: fix vector-length check for AVX512F scalar fused-multiply-add insns

[PATCH v2] x86emul: fix vector-length check for AVX512F scalar fused-multiply-add insns

[Jan Beulich]

The check needs to happen whenever EVEX.b (SDM nomenclature) is clear,
not just in the memory operand case.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Clarify naming (to address apparent disconnect between description
    and code change).

--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -8526,11 +8526,9 @@ x86_emulate(
     case X86EMUL_OPC_EVEX_66(0x0f38, 0xbd): /* vfnmadd231s{s,d} xmm/mem,xmm,xmm{k} */
     case X86EMUL_OPC_EVEX_66(0x0f38, 0xbf): /* vfnmsub231s{s,d} xmm/mem,xmm,xmm{k} */
         host_and_vcpu_must_have(avx512f);
-        if ( ea.type == OP_MEM )
-        {
-            generate_exception_if(evex.br, EXC_UD);
+        generate_exception_if(ea.type != OP_REG && evex.br, EXC_UD);
+        if ( !evex.br )
             avx512_vlen_check(true);
-        }
         goto simd_zmm;
 
     case X86EMUL_OPC(0x0f38, 0xc8):     /* sha1nexte xmm/m128,xmm */



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Re: [PATCH v2] x86emul: fix vector-length check for AVX512F scalar fused-multiply-add insns

[Andrew Cooper]

On 11/12/2018 08:48, Jan Beulich wrote:
> The check needs to happen whenever EVEX.b (SDM nomenclature) is clear,
> not just in the memory operand case.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> v2: Clarify naming (to address apparent disconnect between description
>     and code change).

Thanks - this is much easier to follow.

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

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