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Subject[PATCH 03/11] xen/mmu: Set _PAGE_IOMAP if PFN is an identity PFN.
Date
If we find that the PFN is within the P2M as an identity
PFN make sure to tack on the _PAGE_IOMAP flag.

Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
arch/x86/xen/mmu.c | 18 ++++++++++++++++--
1 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 0180ae8..9c9e076 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -416,8 +416,12 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
if (val & _PAGE_PRESENT) {
unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
pteval_t flags = val & PTE_FLAGS_MASK;
- unsigned long mfn = pfn_to_mfn(pfn);
+ unsigned long mfn;

+ if (!xen_feature(XENFEAT_auto_translated_physmap))
+ mfn = get_phys_to_machine(pfn);
+ else
+ mfn = pfn;
/*
* If there's no mfn for the pfn, then just create an
* empty non-present pte. Unfortunately this loses
@@ -427,8 +431,18 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
if (unlikely(mfn == INVALID_P2M_ENTRY)) {
mfn = 0;
flags = 0;
+ } else {
+ /*
+ * Paramount to do this test _after_ the
+ * INVALID_P2M_ENTRY as INVALID_P2M_ENTRY &
+ * IDENTITY_FRAME_BIT resolves to true.
+ */
+ mfn &= ~FOREIGN_FRAME_BIT;
+ if (mfn & IDENTITY_FRAME_BIT) {
+ mfn &= ~IDENTITY_FRAME_BIT;
+ flags |= _PAGE_IOMAP;
+ }
}
-
val = ((pteval_t)mfn << PAGE_SHIFT) | flags;
}

--
1.7.1


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