diff -r 39f2942fe56b xen/arch/x86/mm/hap/p2m-ept.c --- a/xen/arch/x86/mm/hap/p2m-ept.c Wed May 04 14:46:32 2011 +0100 +++ b/xen/arch/x86/mm/hap/p2m-ept.c Thu May 05 15:43:27 2011 +0100 @@ -579,8 +579,9 @@ static mfn_t ept_get_entry(struct p2m_do goto out; } - - if ( ept_entry->sa_p2mt != p2m_invalid ) + /* Need to check for all-zeroes because typecode 0 is p2m_ram and an + * entirely empty entry shouldn't have RAM type. */ + if ( ept_entry->epte != 0 && ept_entry->sa_p2mt != p2m_invalid ) { *t = ept_entry->sa_p2mt; *a = ept_entry->access; diff -r 39f2942fe56b xen/arch/x86/mm/p2m.c --- a/xen/arch/x86/mm/p2m.c Wed May 04 14:46:32 2011 +0100 +++ b/xen/arch/x86/mm/p2m.c Thu May 05 15:43:27 2011 +0100 @@ -1883,9 +1883,6 @@ static mfn_t p2m_gfn_to_mfn_current(stru p2mt = p2m_flags_to_type(l1e_get_flags(l1e)); ASSERT(l1e_get_pfn(l1e) != INVALID_MFN || !p2m_is_ram(p2mt)); - if ( l1e.l1 == 0 ) - p2mt = p2m_invalid; - if ( p2m_flags_to_type(l1e_get_flags(l1e)) == p2m_populate_on_demand ) { diff -r 39f2942fe56b xen/include/asm-x86/p2m.h --- a/xen/include/asm-x86/p2m.h Wed May 04 14:46:32 2011 +0100 +++ b/xen/include/asm-x86/p2m.h Thu May 05 15:43:27 2011 +0100 @@ -381,12 +381,12 @@ static inline p2m_type_t p2m_flags_to_ty { /* Type is stored in the "available" bits */ #ifdef __x86_64__ - /* - * AMD IOMMU: When we share p2m table with iommu, bit 9 - bit 11 will be - * used for iommu hardware to encode next io page level. Bit 59 - bit 62 - * are used for iommu flags, We could not use these bits to store p2m types. - */ - + /* For AMD IOMMUs we need to use type 0 for plain RAM, but we need + * to make sure that an entirely empty PTE doesn't have RAM type */ + if ( flags == 0 ) + return p2m_invalid; + /* AMD IOMMUs use bits 9-11 to encode next io page level and bits + * 59-62 for iommu flags so we can't use them to store p2m type info. */ return (flags >> 12) & 0x7f; #else return (flags >> 9) & 0x7;