Re: [PATCH v16 2/3] mem_sharing: allow forking domain with IOMMU enabled

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Apr 21, 2020 at 10:47:24AM -0700, Tamas K Lengyel wrote:
> The memory sharing subsystem by default doesn't allow a domain to share memory
> if it has an IOMMU active for obvious security reasons. However, when fuzzing 
> a
> VM fork, the same security restrictions don't necessarily apply. While it 
> makes
> no sense to try to create a full fork of a VM that has an IOMMU attached as 
> only
> one domain can own the pass-through device at a time, creating a shallow fork
> without a device model is still very useful for fuzzing kernel-mode drivers.
> 
> By allowing the parent VM to initialize the kernel-mode driver with a real
> device that's pass-through, the driver can enter into a state more suitable 
> for
> fuzzing. Some of these initialization steps are quite complex and are easier 
> to
> perform when a real device is present. After the initialization, shallow forks
> can be utilized for fuzzing code-segments in the device driver that don't
> directly interact with the device.
> 
> Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks.