[PATCH v3 03/38] virtio: allow __virtioXX, __leXX in config space

Michael S. Tsirkin
2020-08-05T17:13:43Z

Currently all config space fields are of the type __uXX.
This confuses people and some drivers (notably vdpa)
access them using CPU endian-ness - which only
works well for legacy or LE platforms.

Update virtio_cread/virtio_cwrite macros to allow __virtioXX
and __leXX field types. Follow-up patches will convert
config space to use these types.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
---
include/linux/virtio_config.h | 50 +++++++++++++++++++++++++++++++++--
1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 3b4eae5ac5e3..64da491936f7 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -6,6 +6,7 @@
#include <linux/bug.h>
#include <linux/virtio.h>
#include <linux/virtio_byteorder.h>
+#include <linux/compiler_types.h>
#include <uapi/linux/virtio_config.h>

struct irq_affinity;
@@ -287,12 +288,57 @@ static inline __virtio64 cpu_to_virtio64(struct virtio_device *vdev, u64 val)
return __cpu_to_virtio64(virtio_is_little_endian(vdev), val);
}

+/*
+ * Only the checker differentiates between __virtioXX and __uXX types. But we
+ * try to share as much code as we can with the regular GCC build.
+ */
+#if !defined(CONFIG_CC_IS_GCC) && !defined(__CHECKER__)
+
+/* Not a checker - we can keep things simple */
+#define __virtio_native_typeof(x) typeof(x)
+
+#else
+
+/*
+ * We build this out of a couple of helper macros in a vain attempt to
+ * help you keep your lunch down while reading it.
+ */
+#define __virtio_pick_value(x, type, then, otherwise) \
+ __builtin_choose_expr(__same_type(x, type), then, otherwise)
+
+#define __virtio_pick_type(x, type, then, otherwise) \
+ __virtio_pick_value(x, type, (then)0, otherwise)
+
+#define __virtio_pick_endian(x, x16, x32, x64, otherwise) \
+ __virtio_pick_type(x, x16, __u16, \
+ __virtio_pick_type(x, x32, __u32, \
+ __virtio_pick_type(x, x64, __u64, \
+ otherwise)))
+
+#define __virtio_native_typeof(x) typeof( \
+ __virtio_pick_type(x, __u8, __u8, \
+ __virtio_pick_endian(x, __virtio16, __virtio32, __virtio64, \
+ __virtio_pick_endian(x, __le16, __le32, __le64, \
+ __virtio_pick_endian(x, __u16, __u32, __u64, \
+ /* No other type allowed */ \
+ (void)0)))))
+
+#endif
+
+#define __virtio_native_type(structname, member) \
+ __virtio_native_typeof(((structname*)0)->member)
+
+#define __virtio_typecheck(structname, member, val) \
+ /* Must match the member's type, and be integer */ \
+ typecheck(__virtio_native_type(structname, member), (val))
+
+
/* Config space accessors. */
#define virtio_cread(vdev, structname, member, ptr) \
do { \
might_sleep(); \
/* Must match the member's type, and be integer */ \
- if (!typecheck(typeof((((structname*)0)->member)), *(ptr))) \
+ if (!__virtio_typecheck(structname, member, *(ptr))) \
(*ptr) = 1; \
\
switch (sizeof(*ptr)) { \
@@ -322,7 +368,7 @@ static inline __virtio64 cpu_to_virtio64(struct virtio_device *vdev, u64 val)
do { \
might_sleep(); \
/* Must match the member's type, and be integer */ \
- if (!typecheck(typeof((((structname*)0)->member)), *(ptr))) \
+ if (!__virtio_typecheck(structname, member, *(ptr))) \
BUG_ON((*ptr) == 1); \
\
switch (sizeof(*ptr)) { \
--
MST