Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] KVM: x86: Fix x86_decode_insn() return when fetching insn
 bytes fails
To:     Sean Christopherson <sean.j.christopherson@intel.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20190815162032.6679-1-sean.j.christopherson@intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <9bf79098-703c-e82b-7e7d-1c0a6a1023c2@redhat.com>
Date:   Mon, 19 Aug 2019 17:18:33 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <20190815162032.6679-1-sean.j.christopherson@intel.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 15/08/19 18:20, Sean Christopherson 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@intel.com>
> ---
>  arch/x86/kvm/emulate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 8e409ad448f9..6d2273e71020 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -5126,7 +5126,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
>  	else {
>  		rc = __do_insn_fetch_bytes(ctxt, 1);
>  		if (rc != X86EMUL_CONTINUE)
> -			return rc;
> +			goto done;
>  	}
>  
>  	switch (mode) {
> 

Queued, thanks.

Paolo