linux-kernel - Re: [PATCH] KVM: x86: Fix x86_decode_insn() return when fetching insn bytes fails

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Date:   Fri, 16 Aug 2019 14:16:26 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] KVM: x86: Fix x86_decode_insn() return when fetching insn
 bytes fails

On Thu, Aug 15, 2019 at 9:20 AM Sean Christopherson
<sean.j.christopherson@...el.com> wrote:
>
> Jump to the common error handling in x86_decode_insn() if
> __do_insn_fetch_bytes() fails so that its error code is converted to the
> appropriate return type.  Although the various helpers used by
> x86_decode_insn() return X86EMUL_* values, x86_decode_insn() itself
> returns EMULATION_FAILED or EMULATION_OK.
>
> This doesn't cause a functional issue as the sole caller,
> x86_emulate_instruction(), currently only cares about success vs.
> failure, and success is indicated by '0' for both types
> (X86EMUL_CONTINUE and EMULATION_OK).
>
> Fixes: 285ca9e948fa ("KVM: emulate: speed up do_insn_fetch")
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>