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When the handling of a guest stage-2 permission fault races with an MMU notifier, the faulting page might be gone from the guest's stage-2 by the point we attempt to call (p)kvm_pgtable_stage2_relax_perms(). In the normal KVM case, this leads to returning -EAGAIN which user_mem_abort() handles correctly by simply re-entering the guest. However, the pKVM hypercall implementation has additional logic to check the page state using __check_host_shared_guest() which gets confused with absence of a page mapped at the requested IPA and returns -ENOENT, hence breaking user_mem_abort() and hilarity ensues. Luckily, several of the hypercalls for managing the stage-2 page-table of NP guests have no effect on the pKVM ownership tracking (wrprotect, test_clear_young, mkyoung, and crucially relax_perms), so the extra state checking logic is in fact not strictly necessary. So, to fix the discrepancy between standard KVM and pKVM, let's just drop the superfluous __check_host_shared_guest() logic from those hypercalls and make the extra state checking a debug assertion dependent on CONFIG_NVHE_EL2_DEBUG as we already do for other transitions. Signed-off-by: Quentin Perret <qperret@google.com> Reviewed-by: Oliver Upton <oliver.upton@linux.dev> Link: https://lore.kernel.org/r/20250207145438.1333475-3-qperret@google.com Signed-off-by: Marc Zyngier <maz@kernel.org> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| 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 reStructuredText 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.