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a3522ac71f
Rework kvm_mmu_max_mapping_level() to provide the plumbing to consult guest_memfd (and relevant vendor code) when recovering hugepages, e.g. after disabling live migration. The flaw has existed since guest_memfd was originally added, but has gone unnoticed due to lack of guest_memfd support for hugepages or dirty logging. Don't actually call into guest_memfd at this time, as it's unclear as to what the API should be. Ideally, KVM would simply use kvm_gmem_get_pfn(), but invoking kvm_gmem_get_pfn() would lead to sleeping in atomic context if guest_memfd needed to allocate memory (mmu_lock is held). Luckily, the path isn't actually reachable, so just add a TODO and WARN to ensure the functionality is added alongisde guest_memfd hugepage support, and punt the guest_memfd API design question to the future. Note, calling kvm_mem_is_private() in the non-fault path is safe, so long as mmu_lock is held, as hugepage recovery operates on shadow-present SPTEs, i.e. calling kvm_mmu_max_mapping_level() with @fault=NULL is mutually exclusive with kvm_vm_set_mem_attributes() changing the PRIVATE attribute of the gfn. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Fuad Tabba <tabba@google.com> Message-ID: <20250729225455.670324-15-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| drivers | ||
| fs | ||
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| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
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| mm | ||
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| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
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| COPYING | ||
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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 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.