forked from luck/tmp_suning_uos_patched
ddfd1730fd
When installing new memslots, KVM sets bit 0 of the generation number to
indicate that an update is in-progress. Until the update is complete,
there are no guarantees as to whether a vCPU will see the old or the new
memslots. Explicity prevent caching MMIO accesses so as to avoid using
an access cached from the old memslots after the new memslots have been
installed.
Note that it is unclear whether or not disabling caching during the
update window is strictly necessary as there is no definitive
documentation as to what ordering guarantees KVM provides with respect
to updating memslots. That being said, the MMIO spte code does not
allow reusing sptes created while an update is in-progress, and the
associated documentation explicitly states:
We do not want to use an MMIO sptes created with an odd generation
number, ... If KVM is unlucky and creates an MMIO spte while the
low bit is 1, the next access to the spte will always be a cache miss.
At the very least, disabling the per-vCPU MMIO cache during updates will
make its behavior consistent with the MMIO spte behavior and
documentation.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.