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Re: [Qemu-devel] [PATCH] target/i386: Fixed CR0.TS check in gen_sse
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] target/i386: Fixed CR0.TS check in gen_sse |
Date: |
Wed, 27 Jun 2018 11:30:26 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 29/05/2018 12:19, Alexandro Sanchez Bach wrote:
> The function `gen_sse` assumes all of its instructions require CR0.TS=0.
> However, integer extensions at `0F 38 F[0-F]` and `0F 3A F[0-F]` such as
> CRC32, MOVBE, ADX, BMI1, BMI2 that are handled by `gen_sse` are not supposed
> to throw an exception in this scenario. This causes issues while booting
> some FreeBSD-based guests.
>
> Reported-by: Alexandro Sanchez Bach <address@hidden>
> Signed-off-by: Alexandro Sanchez Bach <address@hidden>
> Cc: address@hidden
> diff --git a/target/i386/translate.c b/target/i386/translate.c
> index 7c21814676..079ab7afef 100644
> --- a/target/i386/translate.c
> +++ b/target/i386/translate.c
> @@ -3049,8 +3049,16 @@ static void gen_sse(CPUX86State *env, DisasContext
> *s, int b,
> is_xmm = 1;
> }
> }
> +
> + modrm = x86_ldub_code(env, s);
> + reg = ((modrm >> 3) & 7);
> + if (is_xmm)
> + reg |= rex_r;
> + mod = (modrm >> 6) & 3;
The problem here is that EMMS and FEMMS instructions do not have a
mod/rm byte. However, this change should apply easily on top of another
patch to move EMMS and FEMMS out of gen_sse.
I'll queue the patch, and wait applying it until I have time to do that
other change (or someone else does it ;)).
Thanks,
Paolo
> /* simple MMX/SSE operation */
> - if (s->flags & HF_TS_MASK) {
> + if (s->flags & HF_TS_MASK
> + && ((b != 0x38 && b != 0x3A) || !(modrm & 0xF0))) {
> gen_exception(s, EXCP07_PREX, pc_start - s->cs_base);
> return;
> }
> @@ -3084,11 +3092,6 @@ static void gen_sse(CPUX86State *env, DisasContext
> *s, int b,
> gen_helper_enter_mmx(cpu_env);
> }
>
> - modrm = x86_ldub_code(env, s);
> - reg = ((modrm >> 3) & 7);
> - if (is_xmm)
> - reg |= rex_r;
> - mod = (modrm >> 6) & 3;
> if (sse_fn_epp == SSE_SPECIAL) {
> b |= (b1 << 8);
> switch(b) {
>
>
>