[tests][v9p] Add an example test for VirtIO 9p device

Add a simple test to validate basic functionalities of the VirtIO 9p
device driver, `dev/virtio/9p`.

For now the test attaches to the first v9p device and try to read the
file `LICENSE` under the shared folder. Therefore, if you set the shared
folder to the git root of `lk`, it will read the `LICENSE` of the
littlekernel and dump it to the console after running `v9p_tests`.

For example:

```
starting internet servers
starting app shell
entering main console loop
] v9p_tests
0x80013c08: 2f 2a 0a 20 2a 20 43 6f 70 79 72 69 67 68 74 20 |/*. * Copyright
0x80013c18: 28 63 29 20 32 30 30 38 2d 32 30 31 35 20 54 72 |(c) 2008-2015 Tr
0x80013c28: 61 76 69 73 20 47 65 69 73 65 6c 62 72 65 63 68 |avis Geiselbrech
0x80013c38: 74 0a 20 2a 0a 20 2a 20 50 65 72 6d 69 73 73 69 |t. *. * Permissi
0x80013c48: 6f 6e 20 69 73 20 68 65 72 65 62 79 20 67 72 61 |on is hereby gra
...
```

Signed-off-by: Cody Wong <codycswong@google.com>

app/tests/include/app/tests.h

@@ -19,6 +19,7 @@ int benchmarks(int argc, const console_cmd_args *argv);
 int clock_tests(int argc, const console_cmd_args *argv);
 int printf_tests(int argc, const console_cmd_args *argv);
 int printf_tests_float(int argc, const console_cmd_args *argv);
+int v9p_tests(int argc, const console_cmd_args *argv);
 
 #endif
 

app/tests/rules.mk

@@ -11,6 +11,7 @@ MODULE_SRCS := \
     $(LOCAL_DIR)/tests.c \
     $(LOCAL_DIR)/thread_tests.c \
     $(LOCAL_DIR)/port_tests.c \
+    $(LOCAL_DIR)/v9p_tests.c \
 
 MODULE_FLOAT_SRCS := \
     $(LOCAL_DIR)/benchmarks.c \

app/tests/tests.c

@@ -22,4 +22,5 @@ STATIC_COMMAND("bench", "miscellaneous benchmarks", &benchmarks)
 STATIC_COMMAND("fibo", "threaded fibonacci", &fibo)
 STATIC_COMMAND("spinner", "create a spinning thread", &spinner)
 STATIC_COMMAND("cbuf_tests", "test lib/cbuf", &cbuf_tests)
+STATIC_COMMAND("v9p_tests", "test dev/virtio/9p", &v9p_tests)
 STATIC_COMMAND_END(tests);

app/tests/v9p_tests.c

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2023 Cody Wong
+ *
+ * Use of this source code is governed by a MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT
+ */
+#include <app/tests.h>
+#include <lk/err.h>
+#include <lk/debug.h>
+
+#define FID_ROOT 1
+#define FID_RO 2
+
+#define _LOGF(fmt, args...) \
+    printf("[%s:%d] " fmt, __PRETTY_FUNCTION__, __LINE__, ##args)
+#define LOGF(x...) _LOGF(x)
+
+#if WITH_DEV_VIRTIO_9P
+#include <dev/virtio/9p.h>
+#include <dev/virtio.h>
+
+int v9p_tests(int argc, const console_cmd_args *argv) {
+    struct virtio_device *dev = virtio_get_9p_device(0);
+    status_t status;
+
+    if (dev == NULL) {
+        LOGF("v9p device doesn't exist\n");
+        return ERR_NOT_FOUND;
+    }
+
+    virtio_9p_msg_t tatt = {
+        .msg_type = P9_TATTACH,
+        .tag = P9_TAG_DEFAULT,
+        .msg.tattach = {
+            .fid = FID_ROOT,
+            .afid = P9_FID_NOFID,
+            .uname = "root",
+            .aname = V9P_MOUNT_ANAME,
+            .n_uname = P9_UNAME_NONUNAME
+        }
+    };
+    virtio_9p_msg_t ratt = {};
+
+    status = virtio_9p_rpc(dev, &tatt, &ratt);
+    if (status != NO_ERROR) {
+        LOGF("failed to attach to the host shared folder: %d\n", status);
+        return status;
+    }
+
+    virtio_9p_msg_t twalk = {
+        .msg_type = P9_TWALK,
+        .tag = P9_TAG_DEFAULT,
+        .msg.twalk = {
+            .fid = FID_ROOT, .newfid = FID_RO, .nwname = 1,
+            .wname = {"LICENSE"}
+        }
+    };
+    virtio_9p_msg_t rwalk = {};
+
+    status = virtio_9p_rpc(dev, &twalk, &rwalk);
+    if (status != NO_ERROR) {
+        LOGF("failed to walk to the target file: %d\n", status);
+        return status;
+    }
+
+    virtio_9p_msg_t tlopen = {
+        .msg_type= P9_TLOPEN,
+        .tag = P9_TAG_DEFAULT,
+        .msg.tlopen = {
+            .fid = FID_RO, .flags = O_RDWR,
+        }
+    };
+    virtio_9p_msg_t rlopen = {};
+
+    status = virtio_9p_rpc(dev, &tlopen, &rlopen);
+    if (status != NO_ERROR) {
+        LOGF("failed to open the target file: %d\n", status);
+        return status;
+    }
+
+    virtio_9p_msg_t tread = {
+        .msg_type= P9_TREAD,
+        .tag = P9_TAG_DEFAULT,
+        .msg.tread = {
+            .fid = FID_RO, .offset = 0, .count = 1024
+        }
+    };
+    virtio_9p_msg_t rread = {};
+
+    status = virtio_9p_rpc(dev, &tread, &rread);
+    if (status != NO_ERROR) {
+        LOGF("failed to read the target file: %d\n", status);
+        return status;
+    }
+
+    hexdump8(rread.msg.rread.data, rread.msg.rread.count);
+
+    return NO_ERROR;
+}
+#else
+int v9p_tests(int argc, const console_cmd_args *argv) {
+    LOGF("platform didn't have dev/virtio/9p supported\n");
+    return ERR_NOT_SUPPORTED;
+}
+#endif // WITH_DEV_VIRTIO_9P