a151aceca1
Drop RCU protection after processing each root when handling MMU notifier hooks that aren't the "unmap" path, i.e. aren't zapping. Temporarily drop RCU to let RCU do its thing between roots, and to make it clear that there's no special behavior that relies on holding RCU across all roots. Currently, the RCU protection is completely superficial, it's necessary only to make rcu_dereference() of SPTE pointers happy. A future patch will rely on holding RCU as a proxy for vCPUs in the guest, e.g. to ensure shadow pages aren't freed before all vCPUs do a TLB flush (or rather, acknowledge the need for a flush), but in that case RCU needs to be held until the flush is complete if and only if the flush is needed because a shadow page may have been removed. And except for the "unmap" path, MMU notifier events cannot remove SPs (don't toggle PRESENT bit, and can't change the PFN for a SP). Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Ben Gardon <bgardon@google.com> Message-Id: <20220226001546.360188-10-seanjc@google.com> Reviewed-by: Mingwei Zhang <mizhang@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.