c0db19232c
Move the assertion on the in-progress invalidation count from the primary MMU's notifier path to KVM's common notification path, i.e. assert that the count doesn't go negative even when the invalidation is coming from KVM itself. Opportunistically convert the assertion to a KVM_BUG_ON(), i.e. kill only the affected VM, not the entire kernel. A corrupted count is fatal to the VM, e.g. the non-zero (negative) count will cause mmu_invalidate_retry() to block any and all attempts to install new mappings. But it's far from guaranteed that an end() without a start() is fatal or even problematic to anything other than the target VM, e.g. the underlying bug could simply be a duplicate call to end(). And it's much more likely that a missed invalidation, i.e. a potential use-after-free, would manifest as no notification whatsoever, not an end() without a start(). Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fuad Tabba <tabba@google.com> Tested-by: Fuad Tabba <tabba@google.com> Message-Id: <20231027182217.3615211-3-seanjc@google.com> Reviewed-by: Kai Huang <kai.huang@intel.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.