linux-kernel - [PATCH v2 00/10] Independent per-CPU data section for nVHE

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Date:   Thu,  3 Sep 2020 11:17:02 +0200
From:   David Brazdil <dbrazdil@...gle.com>
To:     Marc Zyngier <maz@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Dennis Zhou <dennis@...nel.org>,
        Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
        Arnd Bergmann <arnd@...db.de>
Cc:     James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, linux-arch@...r.kernel.org,
        kernel-team@...roid.com, David Brazdil <dbrazdil@...gle.com>
Subject: [PATCH v2 00/10] Independent per-CPU data section for nVHE

Introduce '.hyp.data..percpu' as part of ongoing effort to make nVHE
hyp code self-contained and independent of the rest of the kernel.

The series builds on top of the "Split off nVHE hyp code" series which
used objcopy to rename '.text' to '.hyp.text' and prefix all ELF
symbols with '__kvm_nvhe' for all object files under kvm/hyp/nvhe.

The series is structured as follows:

 - patch 1: Modify generic PERCPU_* linker script macros to make it
     possible to define multiple per-CPU ELF sections with prefixed
     section and symbol names.

 - patch 2: Improve existing hyp build rules. This could be sent and merged
    independently of per-CPU but this series builds on it.

 - patches 3-4: Replace hyp helpers for accessing per-CPU variables
     with common helpers modified to work correctly in hyp. Per-CPU
     variables can now be accessed with one API anywhere.

 - patches 5-7: Where VHE and nVHE use per-CPU variables defined in
     kernel proper, move their definitions to hyp/ where they are
     duplicated and owned by VHE/nVHE, respectively. Non-VHE hyp code
     now refers only to per-CPU variables defined in its source files.
     Helpers are added so that kernel proper can continue to access
     nVHE hyp variables, same way as it does with other nVHE symbols.

 - patches 8-10: Introduce '.hyp.data..percpu' ELF section and allocate
     memory for every CPU core during KVM init. All nVHE per-CPU state
     is now grouped together in ELF and in memory. Introducing a new
     per-CPU variable does not require adding new memory mappings any
     more. nVHE hyp code cannot accidentally refer to kernel-proper
     per-CPU data as it only has the pointer to its own per-CPU memory.

Patches are rebased on v5.9-rc3 and available in branch 'topic/percpu-v2' at:
    https://android-kvm.googlesource.com/linux

Changes v1 -> v2:
  * 5.9-rc3 base
  * partially link hyp code, add linker script

David Brazdil (10):
  Macros to override naming of percpu symbols and sections
  kvm: arm64: Partially link nVHE hyp code, simplify HYPCOPY
  kvm: arm64: Remove __hyp_this_cpu_read
  kvm: arm64: Remove hyp_adr/ldr_this_cpu
  kvm: arm64: Add helpers for accessing nVHE hyp per-cpu vars
  kvm: arm64: Duplicate arm64_ssbd_callback_required for nVHE hyp
  kvm: arm64: Create separate instances of kvm_host_data for VHE/nVHE
  kvm: arm64: Mark hyp stack pages reserved
  kvm: arm64: Set up hyp percpu data for nVHE
  kvm: arm64: Remove unnecessary hyp mappings

 arch/arm64/include/asm/assembler.h        |  27 ++++--
 arch/arm64/include/asm/kvm_asm.h          |  74 ++++++++-------
 arch/arm64/include/asm/kvm_host.h         |   2 +-
 arch/arm64/include/asm/kvm_mmu.h          |  23 ++---
 arch/arm64/include/asm/percpu.h           |  33 ++++++-
 arch/arm64/include/asm/sections.h         |   1 +
 arch/arm64/kernel/image-vars.h            |   2 -
 arch/arm64/kernel/vmlinux.lds.S           |  10 ++
 arch/arm64/kvm/arm.c                      | 110 ++++++++++++++++++----
 arch/arm64/kvm/hyp/hyp-entry.S            |   2 +-
 arch/arm64/kvm/hyp/include/hyp/debug-sr.h |   4 +-
 arch/arm64/kvm/hyp/include/hyp/switch.h   |   8 +-
 arch/arm64/kvm/hyp/nvhe/Makefile          |  56 +++++------
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S         |  19 ++++
 arch/arm64/kvm/hyp/nvhe/switch.c          |   8 +-
 arch/arm64/kvm/hyp/vhe/switch.c           |   5 +-
 arch/arm64/kvm/hyp/vhe/sysreg-sr.c        |   4 +-
 arch/arm64/kvm/pmu.c                      |  13 ++-
 include/asm-generic/vmlinux.lds.h         |  40 +++++---
 19 files changed, 304 insertions(+), 137 deletions(-)
 create mode 100644 arch/arm64/kvm/hyp/nvhe/hyp.lds.S

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2.28.0.402.g5ffc5be6b7-goog