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target/i386: Check CR0.TS before enter_mmx

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When CR0.TS=1, execution of x87 FPU, MMX, and some SSE instructions will
cause a Device Not Available (DNA) exception (#NM). System software uses
this exception event to lazily context switch FPU state.

Before this patch, enter_mmx helpers may be generated just before #NM
generation, prematurely resetting FPU state before the guest has a
chance to save it.

Signed-off-by: Matt Borgerson <contact@mborgerson.com>
Message-ID: <CADc=-s5F10muEhLs4f3mxqsEPAHWj0XFfOC2sfFMVHrk9fcpMg@mail.gmail.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Matt Borgerson 2023-07-13 00:29:01 -07:00 committed by Paolo Bonzini
parent c26d005e62
commit b2ea6450d8
1 changed files with 6 additions and 4 deletions
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10
target/i386/tcg/decode-new.c.inc
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@ -1803,16 +1803,18 @@ static void disas_insn_new(DisasContext *s, CPUState *cpu, int b)
}
break;
case X86_SPECIAL_MMX:
if (!(s->prefix & (PREFIX_REPZ | PREFIX_REPNZ | PREFIX_DATA))) {
gen_helper_enter_mmx(cpu_env);
}
default:
break;
}
if (!validate_vex(s, &decode)) {
return;
}
if (decode.e.special == X86_SPECIAL_MMX &&
!(s->prefix & (PREFIX_REPZ | PREFIX_REPNZ | PREFIX_DATA))) {
gen_helper_enter_mmx(cpu_env);
}
if (decode.op[0].has_ea || decode.op[1].has_ea || decode.op[2].has_ea) {
gen_load_ea(s, &decode.mem, decode.e.vex_class == 12);
}