mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-02-16 22:25:13 -05:00
c353fde17d
With the introduction of stage-2 huge mappings in the pKVM hypervisor, guest pages CMO is needed for PMD_SIZE size. Fixmap only supports PAGE_SIZE and iterating over the huge-page is time consuming (mostly due to TLBI on hyp_fixmap_unmap) which is a problem for EL2 latency. Introduce a shared PMD_SIZE fixmap (hyp_fixblock_map/hyp_fixblock_unmap) to improve guest page CMOs when stage-2 huge mappings are installed. On a Pixel6, the iterative solution resulted in a latency of ~700us, while the PMD_SIZE fixmap reduces it to ~100us. Because of the horrendous private range allocation that would be necessary, this is disabled for 64KiB pages systems. Suggested-by: Quentin Perret <qperret@google.com> Signed-off-by: Vincent Donnefort <vdonnefort@google.com> Signed-off-by: Quentin Perret <qperret@google.com> Link: https://lore.kernel.org/r/20250521124834.1070650-11-vdonnefort@google.com Signed-off-by: Marc Zyngier <maz@kernel.org>