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[0/3] arm64: mm: Model LVA support as a CPU feature

Message ID 20221115143824.2798908-1-ardb@kernel.org (mailing list archive)
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Series arm64: mm: Model LVA support as a CPU feature | expand

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Ard Biesheuvel Nov. 15, 2022, 2:38 p.m. UTC 
Treat LVA support (52-bit virtual addressing) as a CPU feature so we can
rely on code patching, reporting and overrides as usual.

Currently, we enable LVA really early, and have special treatment of it
in the boot paths. However, given that both the ID map and the TTBR1
mapping of the kernel image are guarenteed to require 48 bits at most,
we can boot with 48-bit virtual addressing initially, and switch to
52-bit addressing once we are running from C code and have parsed the
command line to look for CPU feature overrides.

Patch #1 is a drive-by cleanup that can be applied independently.

Patch #2 creates the LVA CPU feature and wires it up.

Patch #3 introduces the MMFR2 CPU feature override, as well as a
arm64.nolva command line option to force 48-bit virtual addressing even
if the CPU supports LVA. While at it, E0PD is wired up as an override as
well, given that it sits in MMFR2 as well, and that its value is taken
into account very early too.

Note that this applies onto my series that further refactors the boot
code [0], after a previous refactor landed in v6.0.

[0] https://lore.kernel.org/all/20221111171201.2088501-1-ardb@kernel.org/

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com> 

Ard Biesheuvel (3):
  arm64: mm: get rid of kimage_vaddr global variable
  arm64: mm: Handle LVA support as a CPU feature
  arm64: mm: Add feature override support for LVA and E0PD

 arch/arm64/include/asm/assembler.h    | 17 +++++++------
 arch/arm64/include/asm/cpufeature.h   |  1 +
 arch/arm64/include/asm/memory.h       | 10 ++++----
 arch/arm64/kernel/cpufeature.c        | 19 +++++++++++++-
 arch/arm64/kernel/head.S              | 26 +++-----------------
 arch/arm64/kernel/image-vars.h        |  1 +
 arch/arm64/kernel/pi/idreg-override.c |  8 +++++-
 arch/arm64/kernel/pi/map_kernel.c     | 16 ++++++++++++
 arch/arm64/kernel/sleep.S             |  3 ---
 arch/arm64/mm/mmu.c                   |  8 ------
 arch/arm64/mm/proc.S                  | 16 ++++++------
 arch/arm64/tools/cpucaps              |  1 +
 12 files changed, 70 insertions(+), 56 deletions(-)