Check the length of data written by the device is consistent with the
size of the buffers to avoid out-of-bounds memory accesses in case
values aren't consistent.

Signed-off-by: Andrew Scull <ascull@google.com>
Cc: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

The virtio-rng driver is extremely simple, making it suitable for
testing more of the virtio uclass logic. Have the sandbox driver bind
the virtio-rng driver rather than the virtio-blk driver so it can be
used in tests.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

The virtio sandbox transport was setting the device features value to
the bit index rather than shifting a bit to the right index. Fix this
using the bit manipulation macros.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

When the device returns used buffers, it should refer to the descriptor
that is the head of the descriptor chain for that buffer. Confirm this
to be the case by tracking the head of descriptor chains that have been
made available to the device.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

The shared descriptors should only be written by the guest driver,
however, the device is still able to overwrite and corrupt them.
Maintain a private shadow copy of the descriptors for the driver to
use for state tracking, removing the need to read from the shared
descriptors.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

Move the logic for attaching a descriptor to its own function.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

The variables `total_sg` and `descs_used` have the same value. Replace
the few uses of `total_sg` with `descs_used` to simplify the situation.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

The virtio PCI capabilities describe regions of memory that should be
mapped. Map those with dm_pci_map_bar() which will ensure they are valid
PCI regions.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

Prepare for calls to `virtio_pci_map_capability()` failing by returning
NULL on error. If this happens, later accesses to the pointers would be
unsafe so cause the probe to fail if such an error occurs.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

Add a mask parameter to control the lookup of the PCI region from which
the mapping can be made.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>