tools/virtio: use virt_xxx barriers

Fix build after API changes.

Reported-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

tools/virtio/asm/barrier.h

@@ -1,15 +1,19 @@
 #if defined(__i386__) || defined(__x86_64__)
 #define barrier() asm volatile("" ::: "memory")
-#define mb() __sync_synchronize()
-
-#define smp_mb()	mb()
-# define dma_rmb()	barrier()
-# define dma_wmb()	barrier()
-# define smp_rmb()	barrier()
-# define smp_wmb()	barrier()
+#define virt_mb() __sync_synchronize()
+#define virt_rmb() barrier()
+#define virt_wmb() barrier()
+/* Atomic store should be enough, but gcc generates worse code in that case. */
+#define virt_store_mb(var, value)  do { \
+	typeof(var) virt_store_mb_value = (value); \
+	__atomic_exchange(&(var), &virt_store_mb_value, &virt_store_mb_value, \
+			  __ATOMIC_SEQ_CST); \
+	barrier(); \
+} while (0);
 /* Weak barriers should be used. If not - it's a bug */
-# define rmb()	abort()
-# define wmb()	abort()
+# define mb() abort()
+# define rmb() abort()
+# define wmb() abort()
 #else
 #error Please fill in barrier macros
 #endif

tools/virtio/linux/compiler.h

@@ -0,0 +1,9 @@
+#ifndef LINUX_COMPILER_H
+#define LINUX_COMPILER_H
+
+#define WRITE_ONCE(var, val) \
+	(*((volatile typeof(val) *)(&(var))) = (val))
+
+#define READ_ONCE(var) (*((volatile typeof(val) *)(&(var))))
+
+#endif

tools/virtio/linux/kernel.h

@@ -8,6 +8,7 @@
 #include <assert.h>
 #include <stdarg.h>
 
+#include <linux/compiler.h>
 #include <linux/types.h>
 #include <linux/printk.h>
 #include <linux/bug.h>