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Commitbda324fd03("vdpasim: control virtqueue support") added two new fields (nas, ngroups) to vdpasim_dev_attr, but we forgot to initialize them for vdpa_sim_blk. When creating a new vdpa_sim_blk device this causes the kernel to panic in this way: $ vdpa dev add mgmtdev vdpasim_blk name blk0 BUG: kernel NULL pointer dereference, address: 0000000000000030 ... RIP: 0010:vhost_iotlb_add_range_ctx+0x41/0x220 [vhost_iotlb] ... Call Trace: <TASK> vhost_iotlb_add_range+0x11/0x800 [vhost_iotlb] vdpasim_map_range+0x91/0xd0 [vdpa_sim] vdpasim_alloc_coherent+0x56/0x90 [vdpa_sim] ... This happens because vdpasim->iommu[0] is not initialized when dev_attr.nas is 0. Let's fix this issue by initializing both (nas, ngroups) to 1 for vdpa_sim_blk. Fixes:bda324fd03("vdpasim: control virtqueue support") Cc: gautam.dawar@xilinx.com Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Message-Id: <20220621151323.190431-1-sgarzare@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Eugenio Pérez <eperezma@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.