xen: don't map missing memory
When setting up a pte for a missing pfn (no matching mfn), just create
an empty pte rather than a junk mapping.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index e40ca6e..875f5a0 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -41,10 +41,17 @@
static inline unsigned long pfn_to_mfn(unsigned long pfn)
{
+ unsigned long mfn;
+
if (xen_feature(XENFEAT_auto_translated_physmap))
return pfn;
- return get_phys_to_machine(pfn) & ~FOREIGN_FRAME_BIT;
+ mfn = get_phys_to_machine(pfn);
+
+ if (mfn != INVALID_P2M_ENTRY)
+ mfn &= ~FOREIGN_FRAME_BIT;
+
+ return mfn;
}
static inline int phys_to_machine_mapping_valid(unsigned long pfn)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 9b43bb3..4c63b7f 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -745,7 +745,20 @@
if (val & _PAGE_PRESENT) {
unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
pteval_t flags = val & PTE_FLAGS_MASK;
- val = ((pteval_t)pfn_to_mfn(pfn) << PAGE_SHIFT) | flags;
+ unsigned long mfn = pfn_to_mfn(pfn);
+
+ /*
+ * If there's no mfn for the pfn, then just create an
+ * empty non-present pte. Unfortunately this loses
+ * information about the original pfn, so
+ * pte_mfn_to_pfn is asymmetric.
+ */
+ if (unlikely(mfn == INVALID_P2M_ENTRY)) {
+ mfn = 0;
+ flags = 0;
+ }
+
+ val = ((pteval_t)mfn << PAGE_SHIFT) | flags;
}
return val;