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Re: [Xen-devel] [RFC PATCH v3 05/10] arm/p2m: Make PTE helpers publicly available



Hi Sergej,

On 06/15/2017 12:05 PM, Sergej Proskurin wrote:
In this commit we make the p2m_* helpers, which access PTE properties in
a simplified way, publicly available. This is due to the fact that the
helpers will be used in guest_walk.c in one of the following commits.

Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
---
Cc:
---
  xen/arch/arm/p2m.c        | 23 -----------------------
  xen/include/asm-arm/p2m.h | 27 +++++++++++++++++++++++++++
  2 files changed, 27 insertions(+), 23 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index b7bbea1d81..eecbcdf870 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -46,29 +46,6 @@ static const paddr_t level_masks[] =
  static const uint8_t level_orders[] =
      { ZEROETH_ORDER, FIRST_ORDER, SECOND_ORDER, THIRD_ORDER };
-static inline bool_t p2m_valid(lpae_t pte)
-{
-    return pte.p2m.valid;
-}
-/*
- * These two can only be used on L0..L2 ptes because L3 mappings set
- * the table bit and therefore these would return the opposite to what
- * you would expect.
- */
-static inline bool_t p2m_table(lpae_t pte)
-{
-    return p2m_valid(pte) && pte.p2m.table;
-}
-static inline bool_t p2m_mapping(lpae_t pte)
-{
-    return p2m_valid(pte) && !pte.p2m.table;
-}
-
-static inline bool p2m_is_superpage(lpae_t pte, unsigned int level)
-{
-    return (level < 3) && p2m_mapping(pte);
-}
-
  static void p2m_flush_tlb(struct p2m_domain *p2m);
/* Unlock the flush and do a P2M TLB flush if necessary */
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 18c57f936e..8053f2a0cf 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -198,6 +198,33 @@ static inline int p2m_is_write_locked(struct p2m_domain 
*p2m)
      return rw_is_write_locked(&p2m->lock);
  }
+/*
+ * Helpers to lookup properties of ptes.
+ */
+
+static inline bool_t p2m_valid(lpae_t pte)

The name implies they should only be used for stage-2 page table. But you are using for other place such as for stage-1 page table.

This means that they are in the wrong header (they should go in page.h).

I would actually start to split page.h with lpae.h and short-descriptor.h to avoid mixing two type of page table in the same header. Note that I would be happy if you keep lpae in page.h for the time being. But short-descriptor should definitely go in a separate file.

I would also rename the helpers you move to lpae_*.

+{
+    return pte.p2m.valid;

As you plan to re-use for other things than stage-2 page-table, you use pte.walk rather than pte.p2m.

All those comments applies for the rest of the helpers.

+}
+/*
+ * These two can only be used on L0..L2 ptes because L3 mappings set
+ * the table bit and therefore these would return the opposite to what
+ * you would expect.
+ */
+static inline bool_t p2m_table(lpae_t pte)
+{
+    return p2m_valid(pte) && pte.p2m.table;
+}
+static inline bool_t p2m_mapping(lpae_t pte)
+{
+    return p2m_valid(pte) && !pte.p2m.table;
+}
+
+static inline bool p2m_is_superpage(lpae_t pte, unsigned int level)
+{
+    return (level < 3) && p2m_mapping(pte);
+}
+
  /* Look up the MFN corresponding to a domain's GFN. */
  mfn_t p2m_lookup(struct domain *d, gfn_t gfn, p2m_type_t *t);

Cheers,

--
Julien Grall

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