xen: arm: make p2m operations NOPs

This makes common code less ifdef-y and is consistent with PVHVM on
x86.

Also note that phys_to_machine_mapping_valid should take a pfn
argument and make it do so.

Add __set_phys_to_machine, make set_phys_to_machine a simple wrapper
(on systems with non-nop implementations the outer one can allocate
new p2m pages).

Make __set_phys_to_machine check for identity mapping or invalid only.

Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index 174202318dfff2779ece119e7b45949b82f429e0..c6b9096cef9593fe6508f13768802e1fba98d64c 100644 (file)
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -10,7 +10,7 @@
 #include <xen/interface/grant_table.h>
 
 #define pfn_to_mfn(pfn)                        (pfn)
-#define phys_to_machine_mapping_valid  (1)
+#define phys_to_machine_mapping_valid(pfn) (1)
 #define mfn_to_pfn(mfn)                        (mfn)
 #define mfn_to_virt(m)                 (__va(mfn_to_pfn(m) << PAGE_SHIFT))
 
@@ -30,6 +30,8 @@ typedef struct xpaddr {
 #define XMADDR(x)      ((xmaddr_t) { .maddr = (x) })
 #define XPADDR(x)      ((xpaddr_t) { .paddr = (x) })
 
+#define INVALID_P2M_ENTRY      (~0UL)
+
 static inline xmaddr_t phys_to_machine(xpaddr_t phys)
 {
        unsigned offset = phys.paddr & ~PAGE_MASK;
@@ -74,9 +76,14 @@ static inline int m2p_remove_override(struct page *page, bool clear_pte)
        return 0;
 }
 
+static inline bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+       BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
+       return true;
+}
+
 static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 {
-       BUG();
-       return false;
+       return __set_phys_to_machine(pfn, mfn);
 }
 #endif /* _ASM_ARM_XEN_PAGE_H */