linux-kernel - Re: [PATCH v2] x86/kvm: Disable KVM_ASYNC_PF_SEND

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Message-ID: <20200408100151.GD24663@zn.tnic>
Date:   Wed, 8 Apr 2020 12:01:51 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Vivek Goyal <vgoyal@...hat.com>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        kvm list <kvm@...r.kernel.org>, stable <stable@...r.kernel.org>
Subject: Re: [PATCH v2] x86/kvm: Disable KVM_ASYNC_PF_SEND_ALWAYS

On Tue, Apr 07, 2020 at 06:49:03PM -0400, Vivek Goyal wrote:
> > 2. Access to bad memory results in #MC.  Sure, #MC is a turd, but it’s an *architectural* turd. By all means, have a nice simple PV mechanism to tell the #MC code exactly what went wrong, but keep the overall flow the same as in the native case.
> > 
> 
> Should we differentiate between two error cases. In this case memory is
> not bad. Just that page being asked for can't be faulted in anymore. And
> another error case is real memory failure. So for the first case it
> could be injected into guest using #PF or #VE or something paravirt
> specific and real hardware failures take #MC path (if they are not
> already doing so).

For handling memory failures with guests there's this whole thing
described Documentation/vm/hwpoison.rst and KVM has support for that.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette