From: Paolo Bonzini <pbonzini@redhat.com>
To: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: gregkh@linuxfoundation.org, gleb@redhat.com, kvm@vger.kernel.org,
stable-commits@vger.kernel.org
Subject: Re: [stable-3.4] possibly revert "KVM: X86 emulator: fix source operand decoding..."
Date: Tue, 10 Sep 2013 13:05:21 +0200 [thread overview]
Message-ID: <522EFCF1.6070909@redhat.com> (raw)
In-Reply-To: <20130904164415.GA23288@windriver.com>
Il 04/09/2013 18:44, Paul Gortmaker ha scritto:
> Hi Greg,
>
> The 3.4.44+ cherry pick:
>
> ----------------
> commit 5b5b30580218eae22609989546bac6e44d0eda6e
> Author: Gleb Natapov <gleb@redhat.com>
> Date: Wed Apr 24 13:38:36 2013 +0300
>
> KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions
>
> commit 660696d1d16a71e15549ce1bf74953be1592bcd3 upstream.
>
> Source operand for one byte mov[zs]x is decoded incorrectly if it is in
> high byte register. Fix that.
>
> Signed-off-by: Gleb Natapov <gleb@redhat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ----------------
>
> introduces the following:
>
> arch/x86/kvm/emulate.c: In function ‘decode_operand’:
> arch/x86/kvm/emulate.c:3974:4: warning: passing argument 1 of ‘decode_register’ makes integer from pointer without a cast [enabled by default]
> arch/x86/kvm/emulate.c:789:14: note: expected ‘u8’ but argument is of type ‘struct x86_emulate_ctxt *’
> arch/x86/kvm/emulate.c:3974:4: warning: passing argument 2 of ‘decode_register’ makes pointer from integer without a cast [enabled by default]
> arch/x86/kvm/emulate.c:789:14: note: expected ‘long unsigned int *’ but argument is of type ‘u8’
>
> Based on the severity of the warnings above, I'm reasonably sure there will
> be some kind of runtime regressions due to this, but I stopped to investigate
> the warnings as soon as I saw them, before any run time testing.
>
> It happens because mainline v3.7-rc1~113^2~40 (dd856efafe60) does this:
>
> -static void *decode_register(u8 modrm_reg, unsigned long *regs,
> +static void *decode_register(struct x86_emulate_ctxt *ctxt, u8 modrm_reg,
>
> Since 660696d1d16a71e1 was only applied to stable 3.4, 3.8, and 3.9 -- and
> the prerequisite above is in 3.7+, the issue should be limited to 3.4.44+
Right, the fix is not important to have for 3.4 kernels.
Paolo
next prev parent reply other threads:[~2013-09-10 11:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-04 16:44 [stable-3.4] possibly revert "KVM: X86 emulator: fix source operand decoding..." Paul Gortmaker
2013-09-10 11:05 ` Paolo Bonzini [this message]
2013-09-12 16:55 ` Greg KH
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