Fork of alistair23 Linux kernel for reMarkable from https://github.com/alistair23/linux
e330af7889
VF drivers can trigger PCIe completer aborts any time they read a queue that they don't own. Even in nominal circumstances, it is not possible to prevent the VF driver from reading queues it doesn't own. VF drivers may attempt to read queues it previously owned, but which it no longer does due to a PF reset. Normally these completer aborts aren't an issue. However, on some platforms these trigger machine check errors. This is true even if we lower their severity from fatal to non-fatal. Indeed, we already have code for lowering the severity. We could attempt to mask these errors conditionally around resets, which is the most common time they would occur. However this would essentially be a race between the PF and VF drivers, and we may still occasionally see machine check exceptions on these strictly configured platforms. Instead, mask the errors entirely any time we resume VFs. By doing so, we prevent the completer aborts from being sent to the parent PCIe device, and thus these strict platforms will not upgrade them into machine check errors. Additionally, we don't lose any information by masking these errors, because we'll still report VFs which attempt to access queues via the FUM_BAD_VF_QACCESS errors. Without this change, on platforms where completer aborts cause machine check exceptions, the VF reading queues it doesn't own could crash the host system. Masking the completer abort prevents this, so we should mask it for good, and not just around a PCIe reset. Otherwise malicious or misconfigured VFs could cause the host system to crash. Because we are masking the error entirely, there is little reason to also keep setting the severity bit, so that code is also removed. Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> |
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| README | ||
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.