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[Xen-devel] [PATCH v3 4/6] xen: introduce XEN_GUEST_HANDLE_PARAM



XEN_GUEST_HANDLE_PARAM is going to be used to distinguish guest pointers
stored in memory from guest pointers as hypercall parameters.

guest_handle_* macros default to XEN_GUEST_HANDLE_PARAM as return type.
Two new guest_handle_to_param and guest_handle_from_param macros are
introduced to do conversions.

Changes in v2:

- add 2 missing #define _XEN_GUEST_HANDLE_PARAM for the compilation of
the compat code.

Changes in v3:

- move the guest_handle_cast change into this patch;
- add a clear comment on top of guest_handle_cast;
- also s/XEN_GUEST_HANDLE/XEN_GUEST_HANDLE_PARAM in
  guest_handle_from_ptr and const_guest_handle_from_ptr;
- introduce guest_handle_from_param and guest_handle_to_param.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 xen/include/asm-arm/guest_access.h |   19 ++++++++++++++++---
 xen/include/asm-x86/guest_access.h |   19 ++++++++++++++++---
 xen/include/public/arch-arm.h      |   24 ++++++++++++++++++++----
 xen/include/public/arch-ia64.h     |    9 +++++++++
 xen/include/public/arch-x86/xen.h  |    9 +++++++++
 5 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/xen/include/asm-arm/guest_access.h 
b/xen/include/asm-arm/guest_access.h
index 0fceae6..28a4b3f 100644
--- a/xen/include/asm-arm/guest_access.h
+++ b/xen/include/asm-arm/guest_access.h
@@ -27,16 +27,29 @@ unsigned long raw_clear_guest(void *to, unsigned len);
 #define guest_handle_add_offset(hnd, nr) ((hnd).p += (nr))
 #define guest_handle_subtract_offset(hnd, nr) ((hnd).p -= (nr))
 
-/* Cast a guest handle to the specified type of handle. */
+/* Cast a guest handle (either XEN_GUEST_HANDLE or XEN_GUEST_HANDLE_PARAM)
+ * to the specified type of XEN_GUEST_HANDLE_PARAM. */
 #define guest_handle_cast(hnd, type) ({         \
     type *_x = (hnd).p;                         \
+    (XEN_GUEST_HANDLE_PARAM(type)) { _x };            \
+})
+
+/* Cast a XEN_GUEST_HANDLE to XEN_GUEST_HANDLE_PARAM */
+#define guest_handle_to_param(hnd, type) ({                  \
+    typeof((hnd).p) _x = (hnd).p;                         \
+    (XEN_GUEST_HANDLE_PARAM(type)) { _x };            \
+})
+
+/* Cast a XEN_GUEST_HANDLE_PARAM to XEN_GUEST_HANDLE */
+#define guest_handle_from_param(hnd, type) ({                  \
+    typeof((hnd).p) _x = (hnd).p;                         \
     (XEN_GUEST_HANDLE(type)) { _x };            \
 })
 
 #define guest_handle_from_ptr(ptr, type)        \
-    ((XEN_GUEST_HANDLE(type)) { (type *)ptr })
+    ((XEN_GUEST_HANDLE_PARAM(type)) { (type *)ptr })
 #define const_guest_handle_from_ptr(ptr, type)  \
-    ((XEN_GUEST_HANDLE(const_##type)) { (const type *)ptr })
+    ((XEN_GUEST_HANDLE_PARAM(const_##type)) { (const type *)ptr })
 
 /*
  * Copy an array of objects to guest context via a guest handle,
diff --git a/xen/include/asm-x86/guest_access.h 
b/xen/include/asm-x86/guest_access.h
index 2b429c2..6d35104 100644
--- a/xen/include/asm-x86/guest_access.h
+++ b/xen/include/asm-x86/guest_access.h
@@ -45,16 +45,29 @@
 #define guest_handle_add_offset(hnd, nr) ((hnd).p += (nr))
 #define guest_handle_subtract_offset(hnd, nr) ((hnd).p -= (nr))
 
-/* Cast a guest handle to the specified type of handle. */
+/* Cast a guest handle (either XEN_GUEST_HANDLE or XEN_GUEST_HANDLE_PARAM)
+ * to the specified type of XEN_GUEST_HANDLE_PARAM. */
 #define guest_handle_cast(hnd, type) ({         \
     type *_x = (hnd).p;                         \
+    (XEN_GUEST_HANDLE_PARAM(type)) { _x };            \
+})
+
+/* Cast a XEN_GUEST_HANDLE to XEN_GUEST_HANDLE_PARAM */
+#define guest_handle_to_param(hnd, type) ({                  \
+    typeof((hnd).p) _x = (hnd).p;                         \
+    (XEN_GUEST_HANDLE_PARAM(type)) { _x };            \
+})
+
+/* Cast a XEN_GUEST_HANDLE_PARAM to XEN_GUEST_HANDLE */
+#define guest_handle_from_param(hnd, type) ({                  \
+    typeof((hnd).p) _x = (hnd).p;                         \
     (XEN_GUEST_HANDLE(type)) { _x };            \
 })
 
 #define guest_handle_from_ptr(ptr, type)        \
-    ((XEN_GUEST_HANDLE(type)) { (type *)ptr })
+    ((XEN_GUEST_HANDLE_PARAM(type)) { (type *)ptr })
 #define const_guest_handle_from_ptr(ptr, type)  \
-    ((XEN_GUEST_HANDLE(const_##type)) { (const type *)ptr })
+    ((XEN_GUEST_HANDLE_PARAM(const_##type)) { (const type *)ptr })
 
 /*
  * Copy an array of objects to guest context via a guest handle,
diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index 2ae6548..9db3c81 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -51,18 +51,34 @@
 
 #define XEN_HYPERCALL_TAG   0XEA1
 
+#define uint64_aligned_t uint64_t __attribute__((aligned(8)))
 
 #ifndef __ASSEMBLY__
-#define ___DEFINE_XEN_GUEST_HANDLE(name, type) \
-    typedef struct { type *p; } __guest_handle_ ## name
+#define ___DEFINE_XEN_GUEST_HANDLE(name, type)                  \
+    typedef struct { type *p; }                                 \
+        __guest_handle_ ## name;                                \
+    typedef struct { union { type *p; uint64_aligned_t q; }; }  \
+        __guest_handle_64_ ## name;
 
+/*
+ * XEN_GUEST_HANDLE represents a guest pointer, when passed as a field
+ * in a struct in memory. On ARM is always 8 bytes sizes and 8 bytes
+ * aligned.
+ * XEN_GUEST_HANDLE_PARAM represent a guest pointer, when passed as an
+ * hypercall argument. It is 4 bytes on aarch and 8 bytes on aarch64.
+ */
 #define __DEFINE_XEN_GUEST_HANDLE(name, type) \
     ___DEFINE_XEN_GUEST_HANDLE(name, type);   \
     ___DEFINE_XEN_GUEST_HANDLE(const_##name, const type)
 #define DEFINE_XEN_GUEST_HANDLE(name)   __DEFINE_XEN_GUEST_HANDLE(name, name)
-#define __XEN_GUEST_HANDLE(name)        __guest_handle_ ## name
+#define __XEN_GUEST_HANDLE(name)        __guest_handle_64_ ## name
 #define XEN_GUEST_HANDLE(name)          __XEN_GUEST_HANDLE(name)
-#define set_xen_guest_handle_raw(hnd, val)  do { (hnd).p = val; } while (0)
+/* this is going to be changes on 64 bit */
+#define XEN_GUEST_HANDLE_PARAM(name)    __guest_handle_ ## name
+#define set_xen_guest_handle_raw(hnd, val)                  \
+    do { if ( sizeof(hnd) == 8 ) *(uint64_t *)&(hnd) = 0;   \
+         (hnd).p = val;                                     \
+    } while ( 0 )
 #ifdef __XEN_TOOLS__
 #define get_xen_guest_handle(val, hnd)  do { val = (hnd).p; } while (0)
 #endif
diff --git a/xen/include/public/arch-ia64.h b/xen/include/public/arch-ia64.h
index c9da5d4..e4e9688 100644
--- a/xen/include/public/arch-ia64.h
+++ b/xen/include/public/arch-ia64.h
@@ -45,8 +45,17 @@
     ___DEFINE_XEN_GUEST_HANDLE(name, type);   \
     ___DEFINE_XEN_GUEST_HANDLE(const_##name, const type)
 
+/*
+ * XEN_GUEST_HANDLE represents a guest pointer, when passed as a field
+ * in a struct in memory.
+ * XEN_GUEST_HANDLE_PARAM represent a guest pointer, when passed as an
+ * hypercall argument.
+ * XEN_GUEST_HANDLE_PARAM and XEN_GUEST_HANDLE are the same on ia64 but
+ * they might not be on other architectures.
+ */
 #define DEFINE_XEN_GUEST_HANDLE(name)   __DEFINE_XEN_GUEST_HANDLE(name, name)
 #define XEN_GUEST_HANDLE(name)          __guest_handle_ ## name
+#define XEN_GUEST_HANDLE_PARAM(name)    XEN_GUEST_HANDLE(name)
 #define XEN_GUEST_HANDLE_64(name)       XEN_GUEST_HANDLE(name)
 #define uint64_aligned_t                uint64_t
 #define set_xen_guest_handle_raw(hnd, val)  do { (hnd).p = val; } while (0)
diff --git a/xen/include/public/arch-x86/xen.h 
b/xen/include/public/arch-x86/xen.h
index 1c186d7..0e10260 100644
--- a/xen/include/public/arch-x86/xen.h
+++ b/xen/include/public/arch-x86/xen.h
@@ -38,12 +38,21 @@
     typedef type * __guest_handle_ ## name
 #endif
 
+/*
+ * XEN_GUEST_HANDLE represents a guest pointer, when passed as a field
+ * in a struct in memory.
+ * XEN_GUEST_HANDLE_PARAM represent a guest pointer, when passed as an
+ * hypercall argument.
+ * XEN_GUEST_HANDLE_PARAM and XEN_GUEST_HANDLE are the same on X86 but
+ * they might not be on other architectures.
+ */
 #define __DEFINE_XEN_GUEST_HANDLE(name, type) \
     ___DEFINE_XEN_GUEST_HANDLE(name, type);   \
     ___DEFINE_XEN_GUEST_HANDLE(const_##name, const type)
 #define DEFINE_XEN_GUEST_HANDLE(name)   __DEFINE_XEN_GUEST_HANDLE(name, name)
 #define __XEN_GUEST_HANDLE(name)        __guest_handle_ ## name
 #define XEN_GUEST_HANDLE(name)          __XEN_GUEST_HANDLE(name)
+#define XEN_GUEST_HANDLE_PARAM(name)    XEN_GUEST_HANDLE(name)
 #define set_xen_guest_handle_raw(hnd, val)  do { (hnd).p = val; } while (0)
 #ifdef __XEN_TOOLS__
 #define get_xen_guest_handle(val, hnd)  do { val = (hnd).p; } while (0)
-- 
1.7.2.5


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