[Xen-devel] [PATCH 24/27] xen/arm: page: Describe the layout of flags used to update page tables

[Julien Grall <julien.grall@xxxxxxx>]

Currently, the flags used to update page tables (i.e PAGE_HYPERVISOR_*)
only contains the memory attribute index. Follow-up patches will add
more information in it.

At the same time introduce PAGE_AI_MASK to get the memory attribute
index easily.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/arm/mm.c          | 2 +-
 xen/include/asm-arm/page.h | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 411fe02842..cd7bcf7aca 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1021,7 +1021,7 @@ static int create_xen_entries(enum xenmap_operation op,
                 }
                 if ( op == RESERVE )
                     break;
-                pte = mfn_to_xen_entry(mfn, flags);
+                pte = mfn_to_xen_entry(mfn, PAGE_AI_MASK(flags));
                 pte.pt.table = 1;
                 write_pte(entry, pte);
                 break;
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index d9dac92e73..1bf8e9d012 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -63,6 +63,13 @@
 #define MAIR0VAL (MAIRVAL & 0xffffffff)
 #define MAIR1VAL (MAIRVAL >> 32)
 
+/*
+ * Layout of the flags used for updating the hypervisor page tables
+ *
+ * [0:2] Memory Attribute Index
+ */
+#define PAGE_AI_MASK(x) ((x) & 0x7U)
+
 #define PAGE_HYPERVISOR         (MT_NORMAL)
 #define PAGE_HYPERVISOR_NOCACHE (MT_DEVICE_nGnRE)
 #define PAGE_HYPERVISOR_WC      (MT_NORMAL_NC)
-- 
2.11.0


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