Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2c80b01b authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Linus Torvalds
Browse files

xen: mask _PAGE_PCD from ptes 



_PAGE_PCD maps a page with caching disabled, which is typically used for
mapping harware registers.  Xen never allows it to be set on a mapping, and
unprivileged guests never need it since they can't see the real underlying
hardware.  However, some uncached mappings are made early when probing the
(non-existent) APIC, and its OK to mask off the PCD flag in these cases.

This became necessary because Xen started checking for this bit, rather
than silently masking it off.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c06869d6

arch/x86/xen/mmu.c

+4 −0
Original line number Diff line number Diff line
@@ -244,6 +244,8 @@ pte_t xen_make_pte(unsigned long long pte) 
	if (pte & 1)

		pte = phys_to_machine(XPADDR(pte)).maddr;



	pte &= ~_PAGE_PCD;



	return (pte_t){ pte, pte >> 32 };

}
@@ -291,6 +293,8 @@ pte_t xen_make_pte(unsigned long pte) 
	if (pte & _PAGE_PRESENT)

		pte = phys_to_machine(XPADDR(pte)).maddr;



	pte &= ~_PAGE_PCD;



	return (pte_t){ pte };

}