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-rw-r--r--arch/arm/include/asm/xen/page.h15
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index 98c9fc38b945..e3d94cfa4d46 100644
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -28,6 +28,17 @@ typedef struct xpaddr {
#define INVALID_P2M_ENTRY (~0UL)
+/*
+ * The pseudo-physical frame (pfn) used in all the helpers is always based
+ * on Xen page granularity (i.e 4KB).
+ *
+ * A Linux page may be split across multiple non-contiguous Xen page so we
+ * have to keep track with frame based on 4KB page granularity.
+ *
+ * PV drivers should never make a direct usage of those helpers (particularly
+ * pfn_to_gfn and gfn_to_pfn).
+ */
+
unsigned long __pfn_to_mfn(unsigned long pfn);
extern struct rb_root phys_to_mach;
@@ -64,8 +75,8 @@ static inline unsigned long bfn_to_pfn(unsigned long bfn)
#define bfn_to_local_pfn(bfn) bfn_to_pfn(bfn)
/* VIRT <-> GUEST conversion */
-#define virt_to_gfn(v) (pfn_to_gfn(virt_to_pfn(v)))
-#define gfn_to_virt(m) (__va(gfn_to_pfn(m) << PAGE_SHIFT))
+#define virt_to_gfn(v) (pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT))
+#define gfn_to_virt(m) (__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
/* Only used in PV code. But ARM guests are always HVM. */
static inline xmaddr_t arbitrary_virt_to_machine(void *vaddr)