[PATCH v2] xen/mm: Introduce per-arch pte_attr_t type for PTE flags

[Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>]

Xen's memory management APIs map_pages_to_xen, modify_xen_mappings,
set_fixmap, ioremap_attr, and __vmap all use an unsigned int to
represent architecture-dependent page table entry flags. This assumption
is not well-suited for PPC/radix where some flags go past 32-bits, so
introduce the pte_attr_t type to allow architectures to opt in to larger
types to store PTE flags.

Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
---
Changes in v2:
  - Drop Kconfig option and use `#define pte_attr_t pte_attr_t` for arches to
  opt-in to defining the type.
  - Move default pte_attr_definition to xen/types.h
  - Update commit message to reflect that this change isn't strictly
  necessary for arches w/ >32bit pte flags

 xen/arch/ppc/include/asm/types.h | 3 +++
 xen/arch/ppc/mm-radix.c          | 2 +-
 xen/common/efi/boot.c            | 4 ++--
 xen/common/vmap.c                | 2 +-
 xen/include/xen/mm.h             | 4 ++--
 xen/include/xen/types.h          | 4 ++++
 xen/include/xen/vmap.h           | 3 ++-
 7 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/xen/arch/ppc/include/asm/types.h b/xen/arch/ppc/include/asm/types.h
index ffaf378a4d..9d80e92e44 100644
--- a/xen/arch/ppc/include/asm/types.h
+++ b/xen/arch/ppc/include/asm/types.h
@@ -8,4 +8,7 @@ typedef unsigned long vaddr_t;
 #define INVALID_PADDR (~0UL)
 #define PRIpaddr "016lx"

+typedef unsigned long pte_attr_t;
+#define pte_attr_t pte_attr_t
+
 #endif /* _ASM_PPC_TYPES_H */
diff --git a/xen/arch/ppc/mm-radix.c b/xen/arch/ppc/mm-radix.c
index 24232f3907..e02dffa7c5 100644
--- a/xen/arch/ppc/mm-radix.c
+++ b/xen/arch/ppc/mm-radix.c
@@ -265,7 +265,7 @@ int destroy_xen_mappings(unsigned long s, unsigned long e)
 int map_pages_to_xen(unsigned long virt,
                      mfn_t mfn,
                      unsigned long nr_mfns,
-                     unsigned int flags)
+                     pte_attr_t flags)
 {
     BUG_ON("unimplemented");
 }
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index efbec00af9..c200a27523 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1656,7 +1656,7 @@ void __init efi_init_memory(void)
     struct rt_extra {
         struct rt_extra *next;
         unsigned long smfn, emfn;
-        unsigned int prot;
+        pte_attr_t prot;
     } *extra, *extra_head = NULL;

     free_ebmalloc_unused_mem();
@@ -1671,7 +1671,7 @@ void __init efi_init_memory(void)
         EFI_MEMORY_DESCRIPTOR *desc = efi_memmap + i;
         u64 len = desc->NumberOfPages << EFI_PAGE_SHIFT;
         unsigned long smfn, emfn;
-        unsigned int prot = PAGE_HYPERVISOR_RWX;
+        pte_attr_t prot = PAGE_HYPERVISOR_RWX;
         paddr_t mem_base;
         unsigned long mem_npages;

diff --git a/xen/common/vmap.c b/xen/common/vmap.c
index 47225fecc0..d6991421f3 100644
--- a/xen/common/vmap.c
+++ b/xen/common/vmap.c
@@ -222,7 +222,7 @@ static void vm_free(const void *va)
 }

 void *__vmap(const mfn_t *mfn, unsigned int granularity,
-             unsigned int nr, unsigned int align, unsigned int flags,
+             unsigned int nr, unsigned int align, pte_attr_t flags,
              enum vmap_region type)
 {
     void *va = vm_alloc(nr * granularity, align, type);
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 16f733281a..708705ce72 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -113,9 +113,9 @@ int map_pages_to_xen(
     unsigned long virt,
     mfn_t mfn,
     unsigned long nr_mfns,
-    unsigned int flags);
+    pte_attr_t flags);
 /* Alter the permissions of a range of Xen virtual address space. */
-int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf);
+int modify_xen_mappings(unsigned long s, unsigned long e, pte_attr_t nf);
 void modify_xen_mappings_lite(unsigned long s, unsigned long e,
                               unsigned int nf);
 int destroy_xen_mappings(unsigned long s, unsigned long e);
diff --git a/xen/include/xen/types.h b/xen/include/xen/types.h
index 543bfb2159..8f593c6f74 100644
--- a/xen/include/xen/types.h
+++ b/xen/include/xen/types.h
@@ -18,6 +18,10 @@ typedef signed long ssize_t;

 typedef __PTRDIFF_TYPE__ ptrdiff_t;

+#ifndef pte_attr_t
+typedef unsigned int pte_attr_t;
+#endif
+
 /*
  * Users of this macro are expected to pass a positive value.
  *
diff --git a/xen/include/xen/vmap.h b/xen/include/xen/vmap.h
index 26c831757a..9e2edd1252 100644
--- a/xen/include/xen/vmap.h
+++ b/xen/include/xen/vmap.h
@@ -8,6 +8,7 @@
 #ifndef __XEN_VMAP_H__
 #define __XEN_VMAP_H__

+#include <xen/mm.h>
 #include <xen/mm-frame.h>
 #include <xen/page-size.h>

@@ -57,7 +58,7 @@ void vm_init_type(enum vmap_region type, void *start, void 
*end);
  * @return Pointer to the mapped area on success; NULL otherwise.
  */
 void *__vmap(const mfn_t *mfn, unsigned int granularity, unsigned int nr,
-             unsigned int align, unsigned int flags, enum vmap_region type);
+             unsigned int align, pte_attr_t flags, enum vmap_region type);

 /*
  * Map an array of pages contiguously into the VMAP_DEFAULT vmap region
--
2.30.2