linux-kernel - Re: [PATCH v1 1/8] virtio: Force only split mode with protected guest

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Message-ID: <cc5c8265-83f7-aeb1-bc30-3367fe68bc97@kernel.org>
Date:   Thu, 3 Jun 2021 10:33:39 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Andi Kleen <ak@...ux.intel.com>, mst@...hat.com
Cc:     jasowang@...hat.com, virtualization@...ts.linux-foundation.org,
        hch@....de, m.szyprowski@...sung.com, robin.murphy@....com,
        iommu@...ts.linux-foundation.org, x86@...nel.org,
        sathyanarayanan.kuppuswamy@...ux.intel.com, jpoimboe@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/8] virtio: Force only split mode with protected guest

On 6/2/21 5:41 PM, Andi Kleen wrote:
> Only allow split mode when in a protected guest. Followon
> patches harden the split mode code paths, and we don't want
> an malicious host to force anything else. Also disallow
> indirect mode for similar reasons.

I read this as "the virtio driver is buggy.  Let's disable most of the
buggy code in one special case in which we need a driver without bugs.
In all the other cases (e.g. hardware virtio device connected over
USB-C), driver bugs are still allowed."

Can we just fix the driver without special cases?

--Andy