tree 0e2d5e5f1cdd88bc459e284eb9dc88c1c1b6e7bc
parent 054954eb051f35e74b75a566a96fe756015352c8
author Juergen Gross <jgross@suse.com> 1417172039 +0100
committer David Vrabel <david.vrabel@citrix.com> 1417702160 +0000

xen: Speed up set_phys_to_machine() by using read-only mappings

Instead of checking at each call of set_phys_to_machine() whether a
new p2m page has to be allocated due to writing an entry in a large
invalid or identity area, just map those areas read only and react
to a page fault on write by allocating the new page.

This change will make the common path with no allocation much
faster as it only requires a single write of the new mfn instead
of walking the address translation tables and checking for the
special cases.

Suggested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>