e2b5b21d3a
Add a dedicated helper for zapping a TDP MMU root, and use it in the three flows that do "zap_all" and intentionally do not do a TLB flush if SPTEs are zapped (zapping an entire root is safe if and only if it cannot be in use by any vCPU). Because a TLB flush is never required, unconditionally pass "false" to tdp_mmu_iter_cond_resched() when potentially yielding. Opportunistically document why KVM must not yield when zapping roots that are being zapped by kvm_tdp_mmu_put_root(), i.e. roots whose refcount has reached zero, and further harden the flow to detect improper KVM behavior with respect to roots that are supposed to be unreachable. In addition to hardening zapping of roots, isolating zapping of roots will allow future simplification of zap_gfn_range() by having it zap only leaf SPTEs, and by removing its tricky "zap all" heuristic. By having all paths that truly need to free _all_ SPs flow through the dedicated root zapper, the generic zapper can be freed of those concerns. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Ben Gardon <bgardon@google.com> Message-Id: <20220226001546.360188-16-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.