[PATCH 6.10.y 0/8] arm64: errata: Speculative SSBS workaround

[Mark Rutland <mark.rutland@arm.com>]

Hi,

This series is a v6.10-only backport (based on v6.10.3) of the upstream
workaround for SSBS errata on Arm Ltd CPUs, as affected parts are likely to be
used with stable kernels. This does not apply to earlier stable trees, which
will receive a separate backport.

The errata mean that an MSR to the SSBS special-purpose register does not
affect subsequent speculative instructions, permitting speculative store
bypassing for a window of time.

The upstream support was original posted as:

* https://lore.kernel.org/linux-arm-kernel/20240508081400.235362-1-mark.rutland@arm.com/
  "arm64: errata: Add workaround for Arm errata 3194386 and 3312417"
  Present in v6.10

* https://lore.kernel.org/linux-arm-kernel/20240603111812.1514101-1-mark.rutland@arm.com/
  "arm64: errata: Expand speculative SSBS workaround"
  Present in v6.11-rc1

* https://lore.kernel.org/linux-arm-kernel/20240801101803.1982459-1-mark.rutland@arm.com/
  "arm64: errata: Expand speculative SSBS workaround (again)"
  Present in v6.11-rc2

This backport applies the patches which are not present in v6.10.y.

I have tested the backport (when applied to v6.10.3), ensuring that the
detection logic works and that the HWCAP and string in /proc/cpuinfo are
both hidden when the relevant errata are detected.

Mark.

Mark Rutland (8):
  arm64: cputype: Add Cortex-X3 definitions
  arm64: cputype: Add Cortex-A720 definitions
  arm64: cputype: Add Cortex-X925 definitions
  arm64: errata: Unify speculative SSBS errata logic
  arm64: errata: Expand speculative SSBS workaround
  arm64: cputype: Add Cortex-X1C definitions
  arm64: cputype: Add Cortex-A725 definitions
  arm64: errata: Expand speculative SSBS workaround (again)

 Documentation/arch/arm64/silicon-errata.rst | 34 ++++++++++-
 arch/arm64/Kconfig                          | 62 ++++++++++-----------
 arch/arm64/include/asm/cpucaps.h            |  2 +-
 arch/arm64/include/asm/cputype.h            | 10 ++++
 arch/arm64/kernel/cpu_errata.c              | 26 ++++++---
 arch/arm64/kernel/proton-pack.c             |  2 +-
 6 files changed, 93 insertions(+), 43 deletions(-)

-- 
2.30.2