Hi,
This is an attempt to revive this series originally posted by
Julien Grall[1]. The main motive to work on this now is because
of the requirement to have Pinned KVM VMIDs and the RFC discussion
for the same basically suggested[2] to have a common/better vmid
allocator for KVM which this series provides.
Major Changes from v3:
-Changes related to Pinned ASID support.
-Changes to take care KPTI related bits reservation.
-Dropped support for 32 bit KVM.
-Rebase to 5.12-rc7
Individual patches have change history for any major changes
from v3.
Tests were performed on a HiSilicon D06 platform and so far not observed
any regressions.
For ASID allocation,
Avg of 10 runs(hackbench -s 512 -l 200 -g 300 -f 25 -P),
5.12-rc7: Time:18.8119
5.12-rc7+v4: Time: 18.459
~1.8% improvement.
For KVM VMID,
The measurement was made with maxcpus set to 8 and with the
number of VMID limited to 4-bit. The test involves running
concurrently 40 guests with 2 vCPUs. Each guest will then
execute hackbench 5 times before exiting.
The performance difference between the current algo and the
new one are(ag. of 10 runs):
- 1.9% less exit from the guest
- 0.7% faster
For complete series, please see,
https://github.com/hisilicon/kernel-dev/tree/private-v5.12-rc7-asid-v4
Please take a look and let me know your feedback.
Thanks,
Shameer
[1].https://patchwork.kernel.org/project/linux-arm-kernel/cover/20190724162534.7390-1-julien.grall@xxxxxxx/
[2].https://lore.kernel.org/linux-arm-kernel/20210222155338.26132-6-shameerali.kolothum.thodi@xxxxxxxxxx/T/#mff3129997739e2747172f4a2e81fd66be91ffea4
--------
>From V3:
--------
Hi all,
This patch series is moving out the ASID allocator in a separate file in order
to re-use it for the VMID. The benefits are:
- CPUs are not forced to exit on a roll-over.
- Context invalidation is now per-CPU rather than
broadcasted.
There are no performance regression on the fastpath for ASID allocation.
Actually on the hackbench measurement (300 hackbench) it was .7% faster.
The measurement was made on a Seattle based SoC (8 CPUs), with the
number of VMID limited to 4-bit. The test involves running concurrently 40
guests with 2 vCPUs. Each guest will then execute hackbench 5 times
before exiting.
The performance difference (on 5.1-rc1) between the current algo and the
new one are:
- 2.5% less exit from the guest
- 22.4% more flush, although they are now local rather than broadcasted
- 0.11% faster (just for the record)
The ASID allocator rework to make it generic has been divided in multiple
patches to make the review easier.
A branch with the patch based on 5.3-rc1 can be found:
http://xenbits.xen.org/gitweb/?p=people/julieng/linux-arm.git;a=shortlog;h=refs/heads/vmid-rework/v3
For all the changes see in each patch.
Best regards,
Julien Grall (13):
arm64/mm: Introduce asid_info structure and move
asid_generation/asid_map to it
arm64/mm: Move active_asids and reserved_asids to asid_info
arm64/mm: Move bits to asid_info
arm64/mm: Move the variable lock and tlb_flush_pending to asid_info
arm64/mm: Remove dependency on MM in new_context
arm64/mm: Introduce NUM_CTXT_ASIDS
arm64/mm: Split asid_inits in 2 parts
arm64/mm: Split the function check_and_switch_context in 3 parts
arm64/mm: Introduce a callback to flush the local context
arm64: Move the ASID allocator code in a separate file
arm64/lib: Add an helper to free memory allocated by the ASID
allocator
arch/arm64: Introduce a capability to tell whether 16-bit VMID is
available
kvm/arm: Align the VMID allocation with the arm64 ASID one
Shameer Kolothum (3):
arm64/mm: Move Pinned ASID related variables to asid_info
arm64/mm: Split the arm64_mm_context_get/put
arm64/mm: Introduce a callback to set reserved bits
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/include/asm/kvm_asm.h | 4 +-
arch/arm64/include/asm/kvm_host.h | 5 +-
arch/arm64/include/asm/kvm_mmu.h | 7 +-
arch/arm64/include/asm/lib_asid.h | 87 +++++++++
arch/arm64/kernel/cpufeature.c | 9 +
arch/arm64/kvm/arm.c | 124 +++++--------
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 +-
arch/arm64/kvm/hyp/nvhe/tlb.c | 10 +-
arch/arm64/kvm/hyp/vhe/tlb.c | 10 +-
arch/arm64/kvm/mmu.c | 1 -
arch/arm64/lib/Makefile | 2 +
arch/arm64/lib/asid.c | 264 +++++++++++++++++++++++++++
arch/arm64/mm/context.c | 283 ++++-------------------------
14 files changed, 469 insertions(+), 346 deletions(-)
create mode 100644 arch/arm64/include/asm/lib_asid.h
create mode 100644 arch/arm64/lib/asid.c
--
2.17.1
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