[Xen-devel] [PATCH 2/8] xen: make GUEST_HANDLE_64() and uint64_aligned_t available everywhere

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

GUEST_HANDLE_64() and uint64_aligned_t allow hypercall ABI structures
to be identical (binary compatible) for 32 and 64-bit guests.  They
are currently limited to only being available for use in sysctls and
domctls.  Relax this restriction so they may be used by any new
structures.

There is a minimal cost for 32-bit guests on 64-but hypervisors as
set_xen_guest_handle() needs to zero the whole field on
GUEST_HANDLE_64() handles, but this is expected to be less than the
overhead of having to translate compat structures.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 xen/include/public/arch-x86/xen-x86_32.h |    4 +---
 xen/include/public/xen.h                 |   13 ++++++++-----
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/xen/include/public/arch-x86/xen-x86_32.h 
b/xen/include/public/arch-x86/xen-x86_32.h
index 1504191..f6b4f49 100644
--- a/xen/include/public/arch-x86/xen-x86_32.h
+++ b/xen/include/public/arch-x86/xen-x86_32.h
@@ -91,8 +91,7 @@
 #define machine_to_phys_mapping ((unsigned long *)MACH2PHYS_VIRT_START)
 #endif
 
-/* 32-/64-bit invariability for control interfaces (domctl/sysctl). */
-#if defined(__XEN__) || defined(__XEN_TOOLS__)
+/* 32-/64-bit invariability. */
 #undef ___DEFINE_XEN_GUEST_HANDLE
 #define ___DEFINE_XEN_GUEST_HANDLE(name, type)                  \
     typedef struct { type *p; }                                 \
@@ -107,7 +106,6 @@
 #define uint64_aligned_t uint64_t __attribute__((aligned(8)))
 #define __XEN_GUEST_HANDLE_64(name) __guest_handle_64_ ## name
 #define XEN_GUEST_HANDLE_64(name) __XEN_GUEST_HANDLE_64(name)
-#endif
 
 #ifndef __ASSEMBLY__
 
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 4dd9615..d0aa0c5 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -858,9 +858,14 @@ __DEFINE_XEN_GUEST_HANDLE(uint64, uint64_t);
 
 #endif /* !__ASSEMBLY__ */
 
-/* Default definitions for macros used by domctl/sysctl. */
-#if defined(__XEN__) || defined(__XEN_TOOLS__)
-
+/*
+ * Default definitions for 32/64-bit invariant macros.
+ *
+ * Use these in ABI structures that should be identical for 32 and
+ * 64-bit guests. There is some (very small) overhead in using
+ * XEN_GUEST_HANDLE_64() instead of XEN_GUEST_HANDLE() so avoid for
+ * very hot paths.
+ */
 #ifndef uint64_aligned_t
 #define uint64_aligned_t uint64_t
 #endif
@@ -875,8 +880,6 @@ struct xenctl_cpumap {
 };
 #endif
 
-#endif /* defined(__XEN__) || defined(__XEN_TOOLS__) */
-
 #endif /* __XEN_PUBLIC_XEN_H__ */
 
 /*
-- 
1.7.2.5


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