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Date:   Wed, 14 Apr 2021 17:36:42 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Tianyu Lan <ltykernel@gmail.com>
Cc:     kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com,
        wei.liu@kernel.org, Tianyu Lan <Tianyu.Lan@microsoft.com>,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
        vkuznets@redhat.com, thomas.lendacky@amd.com,
        brijesh.singh@amd.com, sunilmut@microsoft.com
Subject: Re: [RFC V2 PATCH 8/12] UIO/Hyper-V: Not load UIO HV driver in the
 isolation VM.
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References: <20210413152217.3386288-1-ltykernel@gmail.com>
 <20210413152217.3386288-9-ltykernel@gmail.com>
 <YHXAL+83iHPK8O/Q@kroah.com>
 <e54446fb-f9d9-2768-f73f-01a94cf635ea@gmail.com>
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On Wed, Apr 14, 2021 at 11:20:19PM +0800, Tianyu Lan wrote:
> Hi Greg:
> 	Thanks for your review.
> 
> On 4/14/2021 12:00 AM, Greg KH wrote:
> > On Tue, Apr 13, 2021 at 11:22:13AM -0400, Tianyu Lan wrote:
> > > From: Tianyu Lan <Tianyu.Lan@microsoft.com>
> > > 
> > > UIO HV driver should not load in the isolation VM for security reason.
> > 
> > Why?  I need a lot more excuse than that.
> 
> The reason is that ring buffers have been marked as visible to host.
> UIO driver will expose these buffers to user space and user space
> driver hasn't done some secure check for data from host. This
> is considered as insecure in isolation VM.

But as this is a VM choice, why did the VM mark those as visible in the
first place?

thanks,

greg k-h