linux-kernel - Re: [PATCH RESEND] kvm/x86: propagate fetch fault into guest

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Message-ID: <20180920174245.GA10381@linux.intel.com>
Date:   Thu, 20 Sep 2018 10:42:45 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Peng Hao <penghao122@...a.com.cn>, rkrcmar@...hat.com,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org, x86@...nel.org,
        peng.hao2@....com, Peng Hao <peng.hao2@....com.cn>
Subject: Re: [PATCH RESEND] kvm/x86: propagate fetch fault into guest

On Thu, Sep 20, 2018 at 06:32:10PM +0200, Paolo Bonzini wrote:
> On 19/09/2018 16:33, Sean Christopherson wrote:
> > On Tue, 2018-09-18 at 19:03 -0400, Peng Hao wrote:
> >> From: Peng Hao <peng.hao2@....com.cn>
> >>
> >> When handling ept misconfig exit, it will call emulate instruction
> >> with insn_len = 0. The decode instruction function may return a fetch
> >> fault and should propagate to guest.
> > 
> > What fault is encountered, e.g. #PF, #UD, etc...?  Something like a
> > #UD at this point should result in an exit to userspace as it means
> > KVM was unable to emulate an instruction that was successfully
> > decoded by hardware.
> 
> If it's the same bug as https://lore.kernel.org/patchwork/patch/850077/
> it would be a #PF.

Indeed it is, let's move this discussion to that thread.