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x86-64/Xen: eliminate W+X mappings
authorJan Beulich <JBeulich@suse.com>
Mon, 18 Dec 2017 16:37:45 +0000 (09:37 -0700)
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>
Tue, 19 Dec 2017 16:33:25 +0000 (11:33 -0500)
commit2cc42bac1c795f75fcc062b95c6ca7ac1b84d5d8
tree032d75fffa1848d5780f9b4b47e7ae25c52c6a98
parentc4f9d9cb2c29ff04c6b4bb09b72802d8aedfc7cb
x86-64/Xen: eliminate W+X mappings

A few thousand such pages are usually left around due to the re-use of
L1 tables having been provided by the hypervisor (Dom0) or tool stack
(DomU). Set NX in the direct map variant, which needs to be done in L2
due to the dual use of the re-used L1s.

For x86_configure_nx() to actually do what it is supposed to do, call
get_cpu_cap() first. This was broken by commit 4763ed4d45 ("x86, mm:
Clean up and simplify NX enablement") when switching away from the
direct EFER read.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
arch/x86/xen/enlighten_pv.c
arch/x86/xen/mmu_pv.c