EPT differs from NPT and shadow when translating page orders to levels
in the physmap page tables. EPT page tables level for order 0 pages is
0, while NPT and shadow instead use 1, ie: EPT page tables levels
starts at 0 while NPT and shadow starts at 1.
Fix the p2m_entry_modify call in atomic_write_ept_entry to always add
one to the level, in order to match NPT and shadow usage.
While there also add a check to ensure p2m_entry_modify is never
called with level == 0. That should allow to catch future errors
related to the level parameter.
Fixes: c7a4c088ad1c ('x86/mm: split p2m ioreq server pages special handling into helper')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wl@xen.org>
---
Changes since v1:
- Check level is != 0 in p2m_entry_modify.
- Expand digits of hash id.
---
xen/arch/x86/mm/p2m-ept.c | 2 +-
xen/include/asm-x86/p2m.h | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index e3044bee2e..6b8468c793 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -51,7 +51,7 @@ static int atomic_write_ept_entry(struct p2m_domain *p2m,
int level)
{
int rc = p2m_entry_modify(p2m, new.sa_p2mt, entryptr->sa_p2mt,
- _mfn(new.mfn), _mfn(entryptr->mfn), level);
+ _mfn(new.mfn), _mfn(entryptr->mfn), level + 1);
if ( rc )
return rc;
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 09ef7e02fd..aff34e3adf 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -946,6 +946,7 @@ static inline int p2m_entry_modify(struct p2m_domain *p2m, p2m_type_t nt,
p2m_type_t ot, mfn_t nfn, mfn_t ofn,
unsigned int level)
{
+ BUG_ON(!level);
BUG_ON(level > 1 && (nt == p2m_ioreq_server || nt == p2m_map_foreign));
if ( level != 1 || (nt == ot && mfn_eq(nfn, ofn)) )
--
2.20.1 (Apple Git-117)
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> From: Roger Pau Monne [mailto:roger.pau@citrix.com] > Sent: Wednesday, July 3, 2019 7:33 PM > > EPT differs from NPT and shadow when translating page orders to levels > in the physmap page tables. EPT page tables level for order 0 pages is > 0, while NPT and shadow instead use 1, ie: EPT page tables levels > starts at 0 while NPT and shadow starts at 1. > > Fix the p2m_entry_modify call in atomic_write_ept_entry to always add > one to the level, in order to match NPT and shadow usage. > > While there also add a check to ensure p2m_entry_modify is never > called with level == 0. That should allow to catch future errors > related to the level parameter. > > Fixes: c7a4c088ad1c ('x86/mm: split p2m ioreq server pages special handling > into helper') > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
On 03.07.2019 13:33, Roger Pau Monne wrote: > EPT differs from NPT and shadow when translating page orders to levels > in the physmap page tables. EPT page tables level for order 0 pages is > 0, while NPT and shadow instead use 1, ie: EPT page tables levels > starts at 0 while NPT and shadow starts at 1. > > Fix the p2m_entry_modify call in atomic_write_ept_entry to always add > one to the level, in order to match NPT and shadow usage. > > While there also add a check to ensure p2m_entry_modify is never > called with level == 0. That should allow to catch future errors > related to the level parameter. > > Fixes: c7a4c088ad1c ('x86/mm: split p2m ioreq server pages special handling into helper') > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
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