kvmvapic: Disable if there is insufficient memory

[qemu.git] / qemu-barrier.h

diff --git a/qemu-barrier.h b/qemu-barrier.h
index c11bb2b59f01c0dd265080cbe170d2bf08dbd0c8..7e11197814e1e2de566f837d8c9cda409fd9f382 100644 (file)
--- a/qemu-barrier.h
+++ b/qemu-barrier.h
@@ -4,34 +4,61 @@
 /* Compiler barrier */
 #define barrier()   asm volatile("" ::: "memory")
 
-#if defined(__i386__) || defined(__x86_64__)
+#if defined(__i386__)
 
 /*
- * Because of the strongly ordered x86 storage model, wmb() is a nop
+ * Because of the strongly ordered x86 storage model, wmb() and rmb() are nops
  * on x86(well, a compiler barrier only).  Well, at least as long as
  * qemu doesn't do accesses to write-combining memory or non-temporal
  * load/stores from C code.
  */
 #define smp_wmb()   barrier()
+#define smp_rmb()   barrier()
+/*
+ * We use GCC builtin if it's available, as that can use
+ * mfence on 32 bit as well, e.g. if built with -march=pentium-m.
+ * However, on i386, there seem to be known bugs as recently as 4.3.
+ * */
+#if defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 4
+#define smp_mb() __sync_synchronize()
+#else
+#define smp_mb() asm volatile("lock; addl $0,0(%%esp) " ::: "memory")
+#endif
+
+#elif defined(__x86_64__)
+
+#define smp_wmb()   barrier()
+#define smp_rmb()   barrier()
+#define smp_mb() asm volatile("mfence" ::: "memory")
 
 #elif defined(_ARCH_PPC)
 
 /*
- * We use an eieio() for a wmb() on powerpc.  This assumes we don't
+ * We use an eieio() for wmb() on powerpc.  This assumes we don't
  * need to order cacheable and non-cacheable stores with respect to
  * each other
  */
 #define smp_wmb()   asm volatile("eieio" ::: "memory")
 
+#if defined(__powerpc64__)
+#define smp_rmb()   asm volatile("lwsync" ::: "memory")
+#else
+#define smp_rmb()   asm volatile("sync" ::: "memory")
+#endif
+
+#define smp_mb()   asm volatile("sync" ::: "memory")
+
 #else
 
 /*
  * For (host) platforms we don't have explicit barrier definitions
  * for, we use the gcc __sync_synchronize() primitive to generate a
  * full barrier.  This should be safe on all platforms, though it may
- * be overkill.
+ * be overkill for wmb() and rmb().
  */
 #define smp_wmb()   __sync_synchronize()
+#define smp_mb()   __sync_synchronize()
+#define smp_rmb()   __sync_synchronize()
 
 #endif