[RFC PATCH 0/3] Support using physical addresses for RISC-V CMO

[Icenowy Zheng]

Despite the official Zicbom extension only supports virtual addresses,
some vendor-specific extensions, e.g. Xtheadcmo, supports using directly
the physical address.

This patchset tries to provide a CMO alternative macro variant that is
feed with both VA and PA (and the used one can be picked at runtime),
implement it with PA on T-Head cores, and utilize this variant for some
situations that PA is easily accessible.

Tested with an LiteX SoC with OpenC906, with LiteSDCard as root device.

This patchset is based on the fix of dcache.cva encoding, which is at [1].
Without that patch applied, this patchset won't apply cleanly.

[1] https://patchwork.kernel.org/project/linux-riscv/patch/20230103062610.69704-1-uwu@icenowy.me/

Icenowy Zheng (3):
  riscv: errata: cmo: add CMO macro variant with both VA and PA
  riscv: use VA+PA variant of CMO macros for DMA synchorization
  riscv: use VA+PA variant of CMO macros for DMA page preparation

 arch/riscv/include/asm/errata_list.h | 30 ++++++++++++++++++++++++++++
 arch/riscv/mm/dma-noncoherent.c      | 11 +++++-----
 2 files changed, 36 insertions(+), 5 deletions(-)

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2.38.1