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xen: temporary disable SMAP when forwarding hypercalls from user-space

Description

xen: temporary disable SMAP when forwarding hypercalls from user-space

The Xen page-table walker used to resolve the virtual addresses in the
hypercalls will refuse to access user-space pages when SMAP is enabled
unless the AC flag in EFLAGS is set (just like normal hardware with
SMAP support would do).

Since privcmd allows forwarding hypercalls (and buffers) from
user-space into Xen make sure SMAP is temporary disabled for the
duration of the hypercall from user-space.

Approved by: re (gjb)
Sponsored by: Citrix Systems R&D

Details

Provenance
roygerAuthored on
Parents
rS338631: xen: legacy PVH fixes for the new interrupt count
Branches
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