linux-kernel - Re: [PATCH RFC 02/39] KVM: x86/xen: intercept xen hypercalls if enabled

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Message-ID: <f30f1f50-9533-1416-e0ef-79f9fbd8d0e5@oracle.com>
Date:   Wed, 2 Dec 2020 11:17:54 +0000
From:   Joao Martins <joao.m.martins@...cle.com>
To:     David Woodhouse <dwmw2@...radead.org>
Cc:     Ankur Arora <ankur.a.arora@...cle.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 02/39] KVM: x86/xen: intercept xen hypercalls if
 enabled

On 12/1/20 11:19 AM, David Woodhouse wrote:
> On Tue, 2020-12-01 at 09:48 +0000, David Woodhouse wrote:
>> So I switched it to generate the hypercall page directly from the
>> kernel, just like we do for the Hyper-V hypercall page.
> 
> Speaking of Hyper-V... I'll post this one now so you can start heckling
> it.
> 
Xen viridian mode is indeed one thing that needed fixing. And definitely a
separate patch as you do here. Both this one and the previous is looking good.

I suppose that because you switch to kvm_vcpu_write_guest() you no longer need
to validate that the hypercall page is correct neither marking as dirty. Probably
worth making that explicit in the commit message.

> I won't post the rest as I go; not much of the rest of the series when
> I eventually post it will be very new and exciting. It'll just be
> rebasing and tweaking your originals and perhaps adding some tests.
> 

Awesome!!