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Commit 7657ea920c ("KVM: arm64: Use TLBI range-based instructions for
unmap") introduced deferred TLB invalidation for the stage-2 page-table
so that range-based invalidation can be used for the accumulated
addresses. This works fine if the structure of the page-tables remains
unchanged, but if entire tables are zapped and subsequently freed then
we transiently leave the hardware page-table walker with a reference
to freed memory thanks to the translation walk caches. For example,
stage2_unmap_walker() will free page-table pages:
if (childp)
mm_ops->put_page(childp);
and issue the TLB invalidation later in kvm_pgtable_stage2_unmap():
if (stage2_unmap_defer_tlb_flush(pgt))
/* Perform the deferred TLB invalidations */
kvm_tlb_flush_vmid_range(pgt->mmu, addr, size);
For now, take the conservative approach and invalidate the TLB eagerly
when we clear a table entry. Note, however, that the existing level
hint passed to __kvm_tlb_flush_vmid_ipa() is incorrect and will be
fixed in a subsequent patch.
Cc: Raghavendra Rao Ananta <rananta@google.com>
Cc: Shaoqin Huang <shahuang@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240327124853.11206-2-will@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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 reStructuredText 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.