linux-kernel - Re: [PATCH v4] kvm,x86: Exit to user space in case page fault error

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Date:   Tue, 6 Oct 2020 17:04:24 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Vivek Goyal <vgoyal@...hat.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        virtio-fs-list <virtio-fs@...hat.com>, pbonzini@...hat.com
Subject: Re: [PATCH v4] kvm,x86: Exit to user space in case page fault error

On Tue, Oct 06, 2020 at 01:35:27PM -0400, Vivek Goyal wrote:
> On Tue, Oct 06, 2020 at 10:17:04AM -0700, Sean Christopherson wrote:
> 
> [..]
> > > > Note, TDX doesn't allow injection exceptions, so reflecting a #PF back
> > > > into the guest is not an option.  
> > > 
> > > Not even #MC? So sad :-)
> > 
> > Heh, #MC isn't allowed either, yet...
> 
> If #MC is not allowd, logic related to hwpoison memory will not work
> as that seems to inject #MC.

Yep.  Piggybacking #MC is undesirable for other reasons, e.g. adds a "hardware"
dependency for what is really a paravirt feature.