virtio_config: LE config space accessors

To be used by modern code, as well as to handle LE only fields such as
balloon.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 441fd6d..5b5196f 100644 (file)
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -375,6 +375,71 @@ static inline __virtio64 cpu_to_virtio64(struct virtio_device *vdev, u64 val)
                                  sizeof(virtio_cwrite_v));             \
        } while(0)
 
+/*
+ * Nothing virtio-specific about these, but let's worry about generalizing
+ * these later.
+ */
+#define virtio_le_to_cpu(x) \
+       _Generic((x), \
+               __u8: (x), \
+                __le16: le16_to_cpu(x), \
+                __le32: le32_to_cpu(x), \
+                __le64: le64_to_cpu(x) \
+               )
+
+#define virtio_cpu_to_le(x, m) \
+       _Generic((m), \
+                __u8: (x), \
+                __le16: cpu_to_le16(x), \
+                __le32: cpu_to_le32(x), \
+                __le64: cpu_to_le64(x) \
+               )
+
+/* LE (e.g. modern) Config space accessors. */
+#define virtio_cread_le(vdev, structname, member, ptr)                 \
+       do {                                                            \
+               typeof(((structname*)0)->member) virtio_cread_v;        \
+                                                                       \
+               might_sleep();                                          \
+               /* Sanity check: must match the member's type */        \
+               typecheck(typeof(virtio_le_to_cpu(virtio_cread_v)), *(ptr)); \
+                                                                       \
+               switch (sizeof(virtio_cread_v)) {                       \
+               case 1:                                                 \
+               case 2:                                                 \
+               case 4:                                                 \
+                       vdev->config->get((vdev),                       \
+                                         offsetof(structname, member), \
+                                         &virtio_cread_v,              \
+                                         sizeof(virtio_cread_v));      \
+                       break;                                          \
+               default:                                                \
+                       __virtio_cread_many((vdev),                     \
+                                         offsetof(structname, member), \
+                                         &virtio_cread_v,              \
+                                         1,                            \
+                                         sizeof(virtio_cread_v));      \
+                       break;                                          \
+               }                                                       \
+               *(ptr) = virtio_le_to_cpu(virtio_cread_v);              \
+       } while(0)
+
+/* Config space accessors. */
+#define virtio_cwrite_le(vdev, structname, member, ptr)                        \
+       do {                                                            \
+               typeof(((structname*)0)->member) virtio_cwrite_v =      \
+                       virtio_cpu_to_le(*(ptr), ((structname*)0)->member); \
+                                                                       \
+               might_sleep();                                          \
+               /* Sanity check: must match the member's type */        \
+               typecheck(typeof(virtio_le_to_cpu(virtio_cwrite_v)), *(ptr)); \
+                                                                       \
+               vdev->config->set((vdev), offsetof(structname, member), \
+                                 &virtio_cwrite_v,                     \
+                                 sizeof(virtio_cwrite_v));             \
+       } while(0)
+
+
 /* Read @count fields, @bytes each. */
 static inline void __virtio_cread_many(struct virtio_device *vdev,
                                       unsigned int offset,