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[00/15] Split off nVHE hyp code

Message ID 20200430144831.59194-1-dbrazdil@google.com (mailing list archive)
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Series Split off nVHE hyp code | expand

Message

David Brazdil April 30, 2020, 2:48 p.m. UTC 
Refactor files in arch/arm64/kvm/hyp to compile all code which runs in EL2
under nVHE into separate object files from the rest of KVM. This is done in
preparation for being able to unmap .hyp.text from EL1 but has other benefits,
notably:
 * safe use of KASAN/UBSAN/GCOV instrumentation on VHE code,
 * cleaner HVC API,
 * no need for __hyp_text annotations.

nVHE-specific code is moved to hyp/nvhe and compiled with custom build rules
similar to those used by EFI stub. Shared source files are compiled under both
VHE and nVHE build rules. Where a source file contained both VHE and nVHE code,
it is split into a shared header file and two C source files. This is done one
file per commit to make review easier.

All nVHE symbols are prefixed with "__hyp_text_" to avoid collisions with VHE
variants (also inspired by EFI stub). Since this prefixes unresolved symbols
too, image-vars.h contains a list of kernel symbol aliases where nVHE code
still refers to kernel proper. This list will be further reduced in the future.

No functional changes are intended but code was simplified whenever the
refactoring made it possible.

Tested by running kvm-unit-tests on QEMU 5.0 with VHE/nVHE and GIC v2/v3.

This is based off Fuad Tabba's patch series "KVM: arm64: Tidy up arch Kconfig
and Makefiles". Available in branch 'topic/el2-obj' of git repo:
  https://android-kvm.googlesource.com/linux

-David

David Brazdil (13):
  arm64: kvm: Fix symbol dependency in __hyp_call_panic_nvhe
  arm64: kvm: Add build rules for separate nVHE object files
  arm64: kvm: Build hyp-entry.S separately for VHE/nVHE
  arm64: kvm: Move __smccc_workaround_1_smc to .rodata
  arm64: kvm: Split hyp/tlb.c to VHE/nVHE
  arm64: kvm: Split hyp/switch.c to VHE/nVHE
  arm64: kvm: Split hyp/debug-sr.c to VHE/nVHE
  arm64: kvm: Split hyp/sysreg-sr.c to VHE/nVHE
  arm64: kvm: Split hyp/timer-sr.c to VHE/nVHE
  arm64: kvm: Compile remaining hyp/ files for both VHE/nVHE
  arm64: kvm: Add comments around __hyp_text_ symbol aliases
  arm64: kvm: Remove __hyp_text macro, use build rules instead
  arm64: kvm: Lift instrumentation restrictions on VHE

Quentin Perret (2):
  arm64: kvm: Unify users of HVC instruction
  arm64: kvm: Formalize host-hyp hypcall ABI

 arch/arm64/include/asm/kvm_asm.h             |  26 +-
 arch/arm64/include/asm/kvm_emulate.h         |   2 +-
 arch/arm64/include/asm/kvm_host.h            |  32 +-
 arch/arm64/include/asm/kvm_host_hypercalls.h |  62 ++
 arch/arm64/include/asm/kvm_hyp.h             |  15 +-
 arch/arm64/include/asm/kvm_mmu.h             |  13 +-
 arch/arm64/include/asm/mmu.h                 |   7 -
 arch/arm64/include/asm/virt.h                |  33 +-
 arch/arm64/kernel/cpu_errata.c               |   2 +-
 arch/arm64/kernel/hyp-stub.S                 |  34 -
 arch/arm64/kernel/image-vars.h               |  44 ++
 arch/arm64/kvm/arm.c                         |   6 +-
 arch/arm64/kvm/hyp.S                         |  13 +-
 arch/arm64/kvm/hyp/Makefile                  |  12 +-
 arch/arm64/kvm/hyp/aarch32.c                 |   6 +-
 arch/arm64/kvm/hyp/debug-sr.c                | 214 +-----
 arch/arm64/kvm/hyp/debug-sr.h                | 165 +++++
 arch/arm64/kvm/hyp/entry.S                   |   1 -
 arch/arm64/kvm/hyp/fpsimd.S                  |   1 -
 arch/arm64/kvm/hyp/hyp-entry.S               |  62 +-
 arch/arm64/kvm/hyp/nvhe/Makefile             |  42 ++
 arch/arm64/kvm/hyp/nvhe/debug-sr.c           |  77 +++
 arch/arm64/kvm/hyp/nvhe/host_hypercall.c     |  22 +
 arch/arm64/kvm/hyp/nvhe/switch.c             | 271 ++++++++
 arch/arm64/kvm/hyp/nvhe/sysreg-sr.c          |  56 ++
 arch/arm64/kvm/hyp/nvhe/timer-sr.c           |  43 ++
 arch/arm64/kvm/hyp/nvhe/tlb.c                |  67 ++
 arch/arm64/kvm/hyp/switch.c                  | 688 +------------------
 arch/arm64/kvm/hyp/switch.h                  | 438 ++++++++++++
 arch/arm64/kvm/hyp/sysreg-sr.c               | 227 +-----
 arch/arm64/kvm/hyp/sysreg-sr.h               | 211 ++++++
 arch/arm64/kvm/hyp/timer-sr.c                |  38 +-
 arch/arm64/kvm/hyp/tlb.c                     | 168 +----
 arch/arm64/kvm/hyp/tlb.h                     | 126 ++++
 arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c     |   4 +-
 arch/arm64/kvm/hyp/vgic-v3-sr.c              | 130 ++--
 arch/arm64/kvm/va_layout.c                   |   2 +-
 scripts/kallsyms.c                           |   1 +
 38 files changed, 1887 insertions(+), 1474 deletions(-)
 create mode 100644 arch/arm64/include/asm/kvm_host_hypercalls.h
 create mode 100644 arch/arm64/kvm/hyp/debug-sr.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/Makefile
 create mode 100644 arch/arm64/kvm/hyp/nvhe/debug-sr.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/host_hypercall.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/switch.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/sysreg-sr.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/timer-sr.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/tlb.c
 create mode 100644 arch/arm64/kvm/hyp/switch.h
 create mode 100644 arch/arm64/kvm/hyp/sysreg-sr.h
 create mode 100644 arch/arm64/kvm/hyp/tlb.h

Comments

Marc Zyngier April 30, 2020, 5:53 p.m. UTC | #1 
Hi David,

Thanks for posting this, looks quite interesting!

On 2020-04-30 15:48, David Brazdil wrote:
> Refactor files in arch/arm64/kvm/hyp to compile all code which runs in 
> EL2
> under nVHE into separate object files from the rest of KVM. This is 
> done in
> preparation for being able to unmap .hyp.text from EL1 but has other 
> benefits,
> notably:
>  * safe use of KASAN/UBSAN/GCOV instrumentation on VHE code,
>  * cleaner HVC API,
>  * no need for __hyp_text annotations.
> 
> nVHE-specific code is moved to hyp/nvhe and compiled with custom build 
> rules
> similar to those used by EFI stub. Shared source files are compiled 
> under both
> VHE and nVHE build rules. Where a source file contained both VHE and 
> nVHE code,
> it is split into a shared header file and two C source files. This is 
> done one
> file per commit to make review easier.

Do you have any figure on how much bigger the final kernel becomes once 
this
is applied? I guess I can find out pretty easily, but this is the kind 
of thing
that would be useful to make part of your cover letter.

I'll try to review this shortly.

Thanks,

         M.
David Brazdil April 30, 2020, 6:57 p.m. UTC | #2 
Hey Marc,

> Do you have any figure on how much bigger the final kernel becomes once this
> is applied? I guess I can find out pretty easily, but this is the kind of
> thing
> that would be useful to make part of your cover letter.
Bloat-o-meter puts the diff at 21KB:
  add/remove: 152/45 grow/shrink: 10/32 up/down: 27882/-6240 (21642)
That said, the size of `Image` hasn't changed at all, not sure why that is.
The size of Image.gz has gone up by 10KB.

> 
> I'll try to review this shortly.
Cheers, no rush.

-David