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Subject: Re: [PATCH v1 1/8] virtio: Force only split mode with protected guest
To:     Andi Kleen <ak@linux.intel.com>, mst@redhat.com
Cc:     jasowang@redhat.com, virtualization@lists.linux-foundation.org,
        hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com,
        iommu@lists.linux-foundation.org, x86@kernel.org,
        sathyanarayanan.kuppuswamy@linux.intel.com, jpoimboe@redhat.com,
        linux-kernel@vger.kernel.org
References: <20210603004133.4079390-1-ak@linux.intel.com>
 <20210603004133.4079390-2-ak@linux.intel.com>
From:   Andy Lutomirski <luto@kernel.org>
Message-ID: <cc5c8265-83f7-aeb1-bc30-3367fe68bc97@kernel.org>
Date:   Thu, 3 Jun 2021 10:33:39 -0700
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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