limit max DMA region size (#545)

Since the dirty bitmap in message replies is allocated based upon the maximum
size of an individual region, add a limit (somewhat arbitrarily 8TiB, which is a
bitmap size of 256MiB). Add a couple of basic tests on the two DMA limits.

Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>

2 files changed, 105 insertions, 0 deletions

diff --git a/test/py/libvfio_user.py b/test/py/libvfio_user.py
index a664da0..b1ebd4b 100644
--- a/test/py/libvfio_user.py
+++ b/test/py/libvfio_user.py
@@ -108,6 +108,10 @@ SERVER_MAX_FDS = 8
 
 SERVER_MAX_MSG_SIZE = 65536
 
+MAX_DMA_REGIONS = 16
+ONE_TB = (1024 * 1024 * 1024 * 1024)
+MAX_DMA_SIZE = (8 * ONE_TB)
+
 # enum vfio_user_command
 VFIO_USER_VERSION                   = 1
 VFIO_USER_DMA_MAP                   = 2
diff --git a/test/py/test_dma_map.py b/test/py/test_dma_map.py
new file mode 100644
index 0000000..3358abc
--- /dev/null
+++ b/test/py/test_dma_map.py
@@ -0,0 +1,101 @@
+#
+# Copyright (c) 2021 Nutanix Inc. All rights reserved.
+#
+# Authors: John Levon <john.levon@nutanix.com>
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#      * Redistributions of source code must retain the above copyright
+#        notice, this list of conditions and the following disclaimer.
+#      * Redistributions in binary form must reproduce the above copyright
+#        notice, this list of conditions and the following disclaimer in the
+#        documentation and/or other materials provided with the distribution.
+#      * Neither the name of Nutanix nor the names of its contributors may be
+#        used to endorse or promote products derived from this software without
+#        specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+#  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+#  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+#  SERVICESLOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+#  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+#  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+#  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+#  DAMAGE.
+#
+
+from libvfio_user import *
+import errno
+
+#
+# NB: this is currently very incomplete
+#
+
+ctx = None
+
+@vfu_dma_register_cb_t
+def dma_register(ctx, info):
+    pass
+
+@vfu_dma_unregister_cb_t
+def dma_unregister(ctx, info):
+    pass
+    return 0
+
+def test_dma_map_setup():
+    global ctx
+
+    ctx = vfu_create_ctx(flags=LIBVFIO_USER_FLAG_ATTACH_NB)
+    assert ctx != None
+
+    ret = vfu_pci_init(ctx)
+    assert ret == 0
+
+    ret = vfu_setup_device_dma(ctx, dma_register, dma_unregister)
+    assert ret == 0
+
+    ret = vfu_realize_ctx(ctx)
+    assert ret == 0
+
+def test_dma_region_too_big():
+    sock = connect_client(ctx)
+
+    payload = vfio_user_dma_map(argsz=len(vfio_user_dma_map()),
+        flags=(VFIO_USER_F_DMA_REGION_READ |
+               VFIO_USER_F_DMA_REGION_WRITE),
+        offset=0, addr=0x10000, size=MAX_DMA_SIZE + 4096)
+
+    hdr = vfio_user_header(VFIO_USER_DMA_MAP, size=len(payload))
+
+    sock.send(hdr + payload)
+    vfu_run_ctx(ctx)
+    get_reply(sock, expect=errno.ENOSPC)
+
+    disconnect_client(ctx, sock)
+
+def test_dma_region_too_many():
+    sock = connect_client(ctx)
+
+    for i in range(1, MAX_DMA_REGIONS + 2):
+        payload = vfio_user_dma_map(argsz=len(vfio_user_dma_map()),
+            flags=(VFIO_USER_F_DMA_REGION_READ |
+                   VFIO_USER_F_DMA_REGION_WRITE),
+            offset=0, addr=0x1000 * i, size=4096)
+
+        hdr = vfio_user_header(VFIO_USER_DMA_MAP, size=len(payload))
+
+        sock.send(hdr + payload)
+        vfu_run_ctx(ctx)
+
+        if i == MAX_DMA_REGIONS + 1:
+            get_reply(sock, expect=errno.EINVAL)
+        else:
+            get_reply(sock)
+
+    disconnect_client(ctx, sock)
+
+def test_dirty_pages_cleanup():
+    vfu_destroy_ctx(ctx)