[v3,0/2] KVM: arm64: Limit stage2_apply_range() batch size to largest block

Message

Oliver Upton Oct. 7, 2022, 11:41 p.m. UTC

Continuing with MMU patches to post, a small series fixing some soft
lockups caused by stage2_apply_range(). Depending on the paging setup,
we could walk a very large amount of memory before dropping the lock and
rescheduling.

Applies to kvmarm-6.1. Tested with KVM selftests and kvm-unit-tests with
all supported page sizes (4K, 16K, 64K). Additionally, I no longer saw
soft lockups with the following:

  ./dirty_log_perf_test -m -2 -s anonymous_thp -b 4G -v 48

v2: https://lore.kernel.org/kvmarm/[e-mail]/

v2 -> v3:
 - Just use the largest block size as the batch size (Marc)

Oliver Upton (2):
  KVM: arm64: Work out supported block level at compile time
  KVM: arm64: Limit stage2_apply_range() batch size to largest block

 arch/arm64/include/asm/kvm_pgtable.h    | 18 +++++++++++++-----
 arch/arm64/include/asm/stage2_pgtable.h | 20 --------------------
 arch/arm64/kvm/mmu.c                    |  9 ++++++++-
 3 files changed, 21 insertions(+), 26 deletions(-)


base-commit: b302ca52ba8235ff0e18c0fa1fa92b51784aef6a

Comments

Marc Zyngier Oct. 9, 2022, 1:36 a.m. UTC | #1

On Fri, 7 Oct 2022 23:41:49 +0000, Oliver Upton wrote:
> Continuing with MMU patches to post, a small series fixing some soft
> lockups caused by stage2_apply_range(). Depending on the paging setup,
> we could walk a very large amount of memory before dropping the lock and
> rescheduling.
> 
> Applies to kvmarm-6.1. Tested with KVM selftests and kvm-unit-tests with
> all supported page sizes (4K, 16K, 64K). Additionally, I no longer saw
> soft lockups with the following:
> 
> [...]

Applied to fixes, thanks!

[1/2] KVM: arm64: Work out supported block level at compile time
      commit: 3b5c082bbfa20d9a57924edd655bbe63fe98ab06
[2/2] KVM: arm64: Limit stage2_apply_range() batch size to largest block
      commit: 5994bc9e05c2f8811f233aa434e391cd2783f0f5

Cheers,

	M.