Re: [PATCH v2] xen: add new hypercall buffer mapping device

[Boris Ostrovsky]

On 06/18/2018 03:36 AM, Juergen Gross wrote:
> For passing arbitrary data from user land to the Xen hypervisor the
> Xen tools today are using mlock()ed buffers. Unfortunately the kernel
> might change access rights of such buffers for brief periods of time
> e.g. for page migration or compaction, leading to access faults in the
> hypervisor, as the hypervisor can't use the locks of the kernel.
>
> In order to solve this problem add a new device node to the Xen privcmd
> driver to easily allocate hypercall buffers via mmap(). The memory is
> allocated in the kernel and just mapped into user space. Marked as
> VM_IO the user mapping will not be subject to page migration et al.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>