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Subject[PATCH RFC 00/14] kvm/arm: Align the VMID allocation with the arm64 ASID one
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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 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 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 5.1-rc1 can be found:

http://xenbits.xen.org/gitweb/?p=people/julieng/linux-arm.git;a=shortlog;h=refs/heads/vmid-rework/rfc

Cheers,

Julien Grall (14):
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: Store the number of asid allocated per context
arm64/mm: Introduce NUM_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: asid: Allow user to update the context under the lock
arm/kvm: Introduce a new VMID allocator
kvm/arm: Align the VMID allocation with the arm64 ASID one

arch/arm/include/asm/kvm_asid.h | 81 +++++++++++++++
arch/arm/include/asm/kvm_asm.h | 2 +-
arch/arm/include/asm/kvm_host.h | 5 +-
arch/arm/include/asm/kvm_hyp.h | 1 +
arch/arm/kvm/Makefile | 1 +
arch/arm/kvm/asid.c | 191 +++++++++++++++++++++++++++++++++++
arch/arm/kvm/hyp/tlb.c | 8 +-
arch/arm64/include/asm/asid.h | 81 +++++++++++++++
arch/arm64/include/asm/kvm_asid.h | 8 ++
arch/arm64/include/asm/kvm_asm.h | 2 +-
arch/arm64/include/asm/kvm_host.h | 5 +-
arch/arm64/kvm/hyp/tlb.c | 10 +-
arch/arm64/lib/Makefile | 2 +
arch/arm64/lib/asid.c | 191 +++++++++++++++++++++++++++++++++++
arch/arm64/mm/context.c | 205 ++++++--------------------------------
virt/kvm/arm/arm.c | 112 +++++++--------------
16 files changed, 638 insertions(+), 267 deletions(-)
create mode 100644 arch/arm/include/asm/kvm_asid.h
create mode 100644 arch/arm/kvm/asid.c
create mode 100644 arch/arm64/include/asm/asid.h
create mode 100644 arch/arm64/include/asm/kvm_asid.h
create mode 100644 arch/arm64/lib/asid.c

--
2.11.0

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