tree 9fb346daedb3157781c5de35040d0f0ad54f6d38
parent d0d3213eaab056428ca551e1c8bd21400c94a684
author Marc Zyngier <marc.zyngier@arm.com> 1426184211 +0000
committer chrome-bot <chrome-bot@chromium.org> 1528919892 -0700

UPSTREAM: arm/arm64: KVM: Implement Stage-2 page aging

Until now, KVM/arm didn't care much for page aging (who was swapping
anyway?), and simply provided empty hooks to the core KVM code. With
server-type systems now being available, things are quite different.

This patch implements very simple support for page aging, by clearing
the Access flag in the Stage-2 page tables. On access fault, the current
fault handling will write the PTE or PMD again, putting the Access flag
back on.

It should be possible to implement a much faster handling for Access
faults, but that's left for a later patch.

With this in place, performance in VMs is degraded much more gracefully.

BUG=chromium:846515
TEST=build/boot on hana with USE=kvm_host

Change-Id: Id9bd1d8513eb035506774e69373723bd89e617ec
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
(cherry picked from commit 35307b9a5f7ebcc8d8db41c73b69c131b48ace2b)
Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1088064
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>