12 Dec
2019
12 Dec
'19
3:35 p.m.
Hi Marc,
On 11/12/2019 16:56, Marc Zyngier wrote:
A device mapping is normally always mapped at Stage-2, since there is very little gain in having it faulted in.
Nonetheless, it is possible to end-up in a situation where the device mapping has been removed from Stage-2 (userspace munmaped the VFIO region, and the MMU notifier did its job), but present in a userspace mapping (userpace has mapped it back at the same address). In such a situation, the device mapping will be demand-paged as the guest performs memory accesses.
This requires to be careful when dealing with mapping size, cache management, and to handle potential execution of a device mapping.
Reviewed-by: James Morse james.morse@arm.com
Thanks,
James