ia64/xen-unstable

changeset 18830:c2a018cdb45d

Fix PSE PAT handling in guest walk.

Guest walk was currently checking for _PAGE_PSE_PAT flag in
guest_l2e_get_flags(). The problem is that this function only checks
for the first 12 bits of the PDE, while _PAGE_PSE_PAT is actually on bit
12 (that is the 13th bit). This caused _PAGE_PAT bit to never been set on
splintered L1s.

Signed-off-by: Gianluca Guida <gianluca.guida@eu.citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Nov 25 11:17:57 2008 +0000 (2008-11-25)
parents e7c421510be9
children b3265ff6c613 4ccee1299bc7
files xen/arch/x86/mm/guest_walk.c
line diff
     1.1 --- a/xen/arch/x86/mm/guest_walk.c	Mon Nov 24 13:57:48 2008 +0000
     1.2 +++ b/xen/arch/x86/mm/guest_walk.c	Tue Nov 25 11:17:57 2008 +0000
     1.3 @@ -193,15 +193,15 @@ guest_walk_tables(struct vcpu *v, unsign
     1.4           * access controls are enforced in the shadow l2e. */
     1.5          int flags = (_PAGE_PRESENT|_PAGE_USER|_PAGE_RW|
     1.6                       _PAGE_ACCESSED|_PAGE_DIRTY);
     1.7 -        /* PSE level 2 entries use bit 12 for PAT; propagate it to bit 7
     1.8 -         * of the level 1. */
     1.9 -        if ( (guest_l2e_get_flags(gw->l2e) & _PAGE_PSE_PAT) ) 
    1.10 -            flags |= _PAGE_PAT;
    1.11 -        /* Copy the cache-control bits to the l1 as well, because we
    1.12 -         * can't represent PAT in the (non-PSE) shadow l2e. :(
    1.13 -         * This could cause problems if a guest ever maps an area of
    1.14 -         * memory with superpages using more than one caching mode. */
    1.15 -        flags |= guest_l2e_get_flags(gw->l2e) & (_PAGE_PWT|_PAGE_PCD);
    1.16 +        /* Import cache-control bits. Note that _PAGE_PAT is actually
    1.17 +         * _PAGE_PSE, and it is always set. We will clear it in case
    1.18 +         * _PAGE_PSE_PAT (bit 12, i.e. first bit of gfn) is clear. */
    1.19 +        flags |= (guest_l2e_get_flags(gw->l2e)
    1.20 +                  & (_PAGE_PAT|_PAGE_PWT|_PAGE_PCD));
    1.21 +        if ( !(gfn_x(start) & 1) )
    1.22 +            /* _PAGE_PSE_PAT not set: remove _PAGE_PAT from flags. */
    1.23 +            flags &= ~_PAGE_PAT;
    1.24 +
    1.25          /* Increment the pfn by the right number of 4k pages.  
    1.26           * The ~0x1 is to mask out the PAT bit mentioned above. */
    1.27          start = _gfn((gfn_x(start) & ~0x1) + guest_l1_table_offset(va));