5f202c1a1d
The iommu_table_ops::xchg_no_kill() callback updates TCE. It is quite possible that not entire table is allocated if it is huge and multilevel so xchg may also allocate subtables. If failed, it returns H_HARDWARE for failed allocation and H_TOO_HARD if it needs it but cannot do because the alloc parameter is "false" (set when called with MMU=off to force retry with MMU=on). The problem is that having separate errors only matters in real mode (MMU=off) but the only caller with alloc="false" does not check the exact error code and simply returns H_TOO_HARD; and for every other mode alloc is "true". Also, the function is also called from the ioctl() handler of the VFIO SPAPR TCE IOMMU subdriver which does not expect hypervisor error codes (H_xxx) and will expose them to the userspace. This converts wrong error codes to -ENOMEM. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200617003835.48831-1-aik@ozlabs.ru
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.