Thanks for your answers. I thought the fact that there was not any warning/exception meant that VMOVDQU was supported, but if it's mistakenly interpreted as MOVDQU then I understand.
I read the mailing list messages on the AVX GSoC you point out, but couldn't find any branch where this work is located. Is there a non- released version of this that can be tested? If I understand correctly, Qemu (or more precisely TCG) supports x86 SIMD instructions up to SSE4.1, but not AVX/AVX2/AVX-512? Thanks. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1861404 Title: AVX instruction VMOVDQU implementation error for YMM registers Status in QEMU: New Bug description: Hi, Tested with Qemu 4.2.0, and with git version bddff6f6787c916b0e9d63ef9e4d442114257739. The x86 AVX instruction VMOVDQU doesn't work properly with YMM registers (32 bytes). It works with XMM registers (16 bytes) though. See the attached test case `ymm.c`: when copying from memory-to-ymm0 and then back from ymm0-to-memory using VMOVDQU, Qemu only copies the first 16 of the total 32 bytes. ``` user@ubuntu ~/Qemu % gcc -o ymm ymm.c -Wall -Wextra -Werror user@ubuntu ~/Qemu % ./ymm 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F user@ubuntu ~/Qemu % ./x86_64-linux-user/qemu-x86_64 -cpu max ymm 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ``` This seems to be because in `translate.c > gen_sse()`, the case handling the VMOVDQU instruction calls `gen_ldo_env_A0` which always performs a 16 bytes copy using two 8 bytes load and store operations (with `tcg_gen_qemu_ld_i64` and `tcg_gen_st_i64`). Instead, the `gen_ldo_env_A0` function should generate a copy with a size corresponding to the used register. ``` static void gen_sse(CPUX86State *env, DisasContext *s, int b, target_ulong pc_start, int rex_r) { [...] case 0x26f: /* movdqu xmm, ea */ if (mod != 3) { gen_lea_modrm(env, s, modrm); gen_ldo_env_A0(s, offsetof(CPUX86State, xmm_regs[reg])); } else { [...] ``` ``` static inline void gen_ldo_env_A0(DisasContext *s, int offset) { int mem_index = s->mem_index; tcg_gen_qemu_ld_i64(s->tmp1_i64, s->A0, mem_index, MO_LEQ); tcg_gen_st_i64(s->tmp1_i64, cpu_env, offset + offsetof(ZMMReg, ZMM_Q(0))); tcg_gen_addi_tl(s->tmp0, s->A0, 8); tcg_gen_qemu_ld_i64(s->tmp1_i64, s->tmp0, mem_index, MO_LEQ); tcg_gen_st_i64(s->tmp1_i64, cpu_env, offset + offsetof(ZMMReg, ZMM_Q(1))); } ``` To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1861404/+subscriptions