[Xen-devel] [RFC PATCH V2 11/14] Introduce some macros for event channels

[Wei Liu <wei.liu2@xxxxxxxxxx>]

For N-level event channels, the shared bitmaps in the hypervisor are by design
not guaranteed to be contigious.

These macros are used to calculate page number / offset within a page of a
given event channel.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/include/asm-x86/config.h |    4 +++-
 xen/include/xen/sched.h      |   13 +++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h
index ce3a7c0..1a40d80 100644
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -8,11 +8,13 @@
 #define __X86_CONFIG_H__
 
 #define LONG_BYTEORDER 3
+#define LONG_BITORDER 6
+#define BYTE_BITORDER 3
 #define CONFIG_PAGING_LEVELS 4
 
 #define BYTES_PER_LONG (1 << LONG_BYTEORDER)
 #define BITS_PER_LONG (BYTES_PER_LONG << 3)
-#define BITS_PER_BYTE 8
+#define BITS_PER_BYTE (1 << BYTE_BITORDER)
 
 #define CONFIG_X86 1
 #define CONFIG_X86_HT 1
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index d6e3a03..0c3af04 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -69,6 +69,19 @@ extern struct domain *dom0;
             __v;})
 
 #define EVTCHNS_PER_BUCKET 512
+/* N.B. EVTCHNS_PER_PAGE is always powers of 2, use shifts to optimize */
+#define EVTCHNS_SHIFT (PAGE_SHIFT+BYTE_BITORDER)
+#define EVTCHNS_PER_PAGE (_AC(1,L) << EVTCHNS_SHIFT)
+#define EVTCHN_MASK (~(EVTCHNS_PER_PAGE-1))
+#define EVTCHN_PAGE_NO(chn) ((chn) >> EVTCHNS_SHIFT)
+#define EVTCHN_OFFSET_IN_PAGE(chn) ((chn) & ~EVTCHN_MASK)
+
+#ifndef CONFIG_COMPAT
+#define EVTCHN_WORD_BITORDER(d) LONG_BITORDER
+#else
+#define EVTCHN_WORD_BITORDER(d) (has_32bit_shinfo(d) ? 5 : LONG_BITORDER)
+#endif
+
 #define NR_EVTCHN_BUCKETS  (NR_EVENT_CHANNELS / EVTCHNS_PER_BUCKET)
 struct xen_evtchn_ops;
 
-- 
1.7.10.4


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