tools/virtio: Add DMA_MAPPING_ERROR and sg_dma_len api define for virtio test

when we build tools/virtio, meet below error information.

cc -g -O2 -Werror -Wno-maybe-uninitialized -Wall -I. -I../include/
-I ../../usr/include/ -Wno-pointer-sign -fno-strict-overflow
-fno-strict-aliasing -fno-common -MMD
-U_FORTIFY_SOURCE -include ../../include/linux/kconfig.h
-mfunction-return=thunk
-fcf-protection=none -mindirect-branch-register -pthread
-c -o virtio_ring.o ../../drivers/virtio/virtio_ring.c

../../drivers/virtio/virtio_ring.c: in function 'vring_need_unmap_buffer':
../../drivers/virtio/virtio_ring.c:294:54: error:'DMA_MAPPING_ERROR'Undeclared (first use within this function)
  294 |         return vring->use_dma_api && (extra->addr != DMA_MAPPING_ERROR);
      |                                                      ^~~~~~~~~~~~~~~~~
../../drivers/virtio/virtio_ring.c:294:54: Note: Each undeclared identifier is only reported once within the function it appears in
../../drivers/virtio/virtio_ring.c: in function 'vring_map_one_sg':
../../drivers/virtio/virtio_ring.c:369:24: error：Implicit declaration function'sg_dma_len' [-Wimplicit-function-declaration]
  369 |                 *len = sg_dma_len(sg);
      |                        ^~~~~~~~~~
../../drivers/virtio/virtio_ring.c: in function'virtqueue_add_desc_split':
../../drivers/virtio/virtio_ring.c:518:37: error:'DMA_MAPPING_ERROR'Undeclared (first use within this function)
  518 |         extra[i].addr = premapped ? DMA_MAPPING_ERROR : addr;
      |                                     ^~~~~~~~~~~~~~~~~
../../drivers/virtio/virtio_ring.c: in function'virtqueue_add_indirect_packed':
../../drivers/virtio/virtio_ring.c:1370:61: error: 'DMA_MAPPING_ERROR'Undeclared (first use within this function)
 1370 |                             extra[i].addr = premapped ? DMA_MAPPING_ERROR : addr;
      |                                                         ^~~~~~~~~~~~~~~~~

../../drivers/virtio/virtio_ring.c: in function'virtqueue_add_packed':
../../drivers/virtio/virtio_ring.c:1535:41: error:'DMA_MAPPING_ERROR'Undeclared (first use within this function)
 1535 |                                         DMA_MAPPING_ERROR : addr;
      |                                         ^~~~~~~~~~~~~~~~~

to fix, add DMA_MAPPING_ERROR define for virtio test.

Fixes: c7e1b42 ("virtio_ring: perform premapped operations based on per-buffer")
Signed-off-by: Yufeng Wang <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>

Author: Yufeng Wang

tools/virtio/linux/dma-mapping.h

@@ -31,6 +31,7 @@ enum dma_data_direction {
 #define dma_unmap_page(d, a, s, r) do { (void)(d); (void)(a); (void)(s); (void)(r); } while (0)
 
 #define sg_dma_address(sg) (0)
+#define sg_dma_len(sg) (0)
 #define dma_need_sync(v, a) (0)
 #define dma_unmap_single_attrs(d, a, s, r, t) do { \
 	(void)(d); (void)(a); (void)(s); (void)(r); (void)(t); \
@@ -43,4 +44,16 @@ enum dma_data_direction {
 } while (0)
 #define dma_max_mapping_size(...) SIZE_MAX
 
+/*
+ * A dma_addr_t can hold any valid DMA or bus address for the platform.  It can
+ * be given to a device to use as a DMA source or target.  It is specific to a
+ * given device and there may be a translation between the CPU physical address
+ * space and the bus address space.
+ *
+ * DMA_MAPPING_ERROR is the magic error code if a mapping failed.  It should not
+ * be used directly in drivers, but checked for using dma_mapping_error()
+ * instead.
+ */
+#define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
+
 #endif