From: Peter Maydell <peter.maydell@linaro.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, ricky@rzhou.org,
Gabriele Svelto <gsvelto@mozilla.com>
Subject: Re: [PATCH] target/i386: fix operand size for VCOMI/VUCOMI instructions
Date: Tue, 9 May 2023 16:09:29 +0100 [thread overview]
Message-ID: <CAFEAcA9Czv2nVqb3sApAda-aru8Pco7vkyN48YCjYa92105WzA@mail.gmail.com> (raw)
In-Reply-To: <20230509142639.253947-1-pbonzini@redhat.com>
On Tue, 9 May 2023 at 15:27, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> Compared to other SSE instructions, VUCOMISx and VCOMISx are different:
> the single and double precision versions are distinguished through a
> prefix, however they use no-prefix and 0x66 for SS and SD respectively.
> Scalar values usually are associated with 0xF2 and 0xF3.
>
> Because of these, they incorrectly perform a 128-bit memory load instead
> of a 32- or 64-bit load. Fix this by writing a custom decoding function.
>
> I tested that the reproducer is fixed and the test-avx output does not
> change.
>
> Reported-by: Gabriele Svelto <gsvelto@mozilla.com>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1637
> Fixes: f8d19eec0d53 ("target/i386: reimplement 0x0f 0x28-0x2f, add AVX", 2022-10-18)
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Worth
Cc: qemu-stable@nongnu.org
also? We have real-world reports of guests falling over on this.
thanks
-- PMM
prev parent reply other threads:[~2023-05-09 15:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-09 14:26 [PATCH] target/i386: fix operand size for VCOMI/VUCOMI instructions Paolo Bonzini
2023-05-09 15:00 ` Richard Henderson
2023-05-09 15:09 ` Peter Maydell [this message]
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