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Introduce KVM_BUG_ON_DATA_CORRUPTION() and use it in the low-level rmap helpers to convert the existing BUG()s to WARN_ON_ONCE() when the kernel is built with CONFIG_BUG_ON_DATA_CORRUPTION=n, i.e. does NOT want to BUG() on corruption of host kernel data structures. Environments that don't have infrastructure to automatically capture crash dumps, i.e. aren't likely to enable CONFIG_BUG_ON_DATA_CORRUPTION=y, are typically better served overall by WARN-and-continue behavior (for the kernel, the VM is dead regardless), as a BUG() while holding mmu_lock all but guarantees the _best_ case scenario is a panic(). Make the BUG()s conditional instead of removing/replacing them entirely as there's a non-zero chance (though by no means a guarantee) that the damage isn't contained to the target VM, e.g. if no rmap is found for a SPTE then KVM may be double-zapping the SPTE, i.e. has already freed the memory the SPTE pointed at and thus KVM is reading/writing memory that KVM no longer owns. Link: https://lore.kernel.org/all/20221129191237.31447-1-mizhang@google.com Suggested-by: Mingwei Zhang <mizhang@google.com> Cc: David Matlack <dmatlack@google.com> Cc: Jim Mattson <jmattson@google.com> Reviewed-by: Mingwei Zhang <mizhang@google.com> Link: https://lore.kernel.org/r/20230729004722.1056172-13-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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.