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c6073743d0
When CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, struct page initialization is deferred to parallel kthreads that run later in the boot process. During KHO restoration, kho_preserved_memory_reserve() writes metadata for each preserved memory region. However, if the struct page has not been initialized, this write targets uninitialized memory, potentially leading to errors like: BUG: unable to handle page fault for address: ... Fix this by introducing kho_get_preserved_page(), which ensures all struct pages in a preserved region are initialized by calling init_deferred_page() which is a no-op when the struct page is already initialized. Signed-off-by: Evangelos Petrongonas <epetron@amazon.de> Co-developed-by: Michal Clapinski <mclapinski@google.com> Signed-off-by: Michal Clapinski <mclapinski@google.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Link: https://patch.msgid.link/20260423122538.140993-3-mclapinski@google.com Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
90 lines
2.8 KiB
Plaintext
90 lines
2.8 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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menu "Live Update and Kexec HandOver"
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config KEXEC_HANDOVER
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bool "kexec handover"
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depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE
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select MEMBLOCK_KHO_SCRATCH
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select KEXEC_FILE
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select LIBFDT
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select CMA
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help
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Allow kexec to hand over state across kernels by generating and
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passing additional metadata to the target kernel. This is useful
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to keep data or state alive across the kexec. For this to work,
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both source and target kernels need to have this option enabled.
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config KEXEC_HANDOVER_DEBUG
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bool "Enable Kexec Handover debug checks"
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depends on KEXEC_HANDOVER
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help
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This option enables extra sanity checks for the Kexec Handover
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subsystem. Since, KHO performance is crucial in live update
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scenarios and the extra code might be adding overhead it is
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only optionally enabled.
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config KEXEC_HANDOVER_DEBUGFS
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bool "kexec handover debugfs interface"
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default KEXEC_HANDOVER
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depends on KEXEC_HANDOVER
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select DEBUG_FS
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help
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Allow to control kexec handover device tree via debugfs
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interface, i.e. finalize the state or aborting the finalization.
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Also, enables inspecting the KHO fdt trees with the debugfs binary
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blobs.
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config KEXEC_HANDOVER_ENABLE_DEFAULT
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bool "Enable kexec handover by default"
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depends on KEXEC_HANDOVER
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help
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Enable Kexec Handover by default. This avoids the need to
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explicitly pass 'kho=on' on the kernel command line.
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This is useful for systems where KHO is a prerequisite for other
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features, such as Live Update, ensuring the mechanism is always
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active.
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The default behavior can still be overridden at boot time by
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passing 'kho=off'.
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config LIVEUPDATE
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bool "Live Update Orchestrator"
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depends on KEXEC_HANDOVER
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help
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Enable the Live Update Orchestrator. Live Update is a mechanism,
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typically based on kexec, that allows the kernel to be updated
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while keeping selected devices operational across the transition.
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These devices are intended to be reclaimed by the new kernel and
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re-attached to their original workload without requiring a device
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reset.
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Ability to handover a device from current to the next kernel depends
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on specific support within device drivers and related kernel
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subsystems.
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This feature primarily targets virtual machine hosts to quickly update
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the kernel hypervisor with minimal disruption to the running virtual
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machines.
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If unsure, say N.
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config LIVEUPDATE_MEMFD
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bool "Live update support for memfd"
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depends on LIVEUPDATE
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depends on MEMFD_CREATE
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depends on SHMEM
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default LIVEUPDATE
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help
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Enable live update support for memfd regions. This allows preserving
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memfd-backed memory across kernel live updates.
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This can be used to back VM memory with memfds, allowing the guest
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memory to persist, or for other user workloads needing to preserve
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pages.
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If unsure, say N.
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endmenu
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