[xen stable-4.18] x86emul: correct #UD check for AVX512-FP16 complex multiplications

[patchbot@xxxxxxx]

commit 4c894c519db69c912d57a122f717ac3d6c81254c
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jan 21 09:27:45 2025 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jan 21 09:27:45 2025 +0100

    x86emul: correct #UD check for AVX512-FP16 complex multiplications
    
    avx512_vlen_check()'s argument was inverted, while the surrounding
    conditional wrongly forced the EVEX.L'L check for the scalar forms when
    embedded rounding was in effect.
    
    Fixes: d14c52cba0f5 ("x86emul: handle AVX512-FP16 complex multiplication 
insns")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: a30d438ce58b70c5955f5d37f776086ab8f88623
    master date: 2024-08-19 15:32:31 +0200
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 2c6bc8df2c..85d8ea7172 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -7948,8 +7948,8 @@ x86_emulate(
         generate_exception_if(modrm_reg == src1 ||
                               (ea.type != OP_MEM && modrm_reg == modrm_rm),
                               X86_EXC_UD);
-        if ( ea.type != OP_REG || (b & 1) || !evex.brs )
-            avx512_vlen_check(!(b & 1));
+        if ( ea.type != OP_REG || !evex.brs )
+            avx512_vlen_check(b & 1);
         goto simd_zmm;
     }
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.18