On some RISC-V platforms, including StarFive JH7100 and ESWIN EIC7700,
RAM is mapped to multiple physical address ranges, with each alias
having a different set of statically-determined Physical Memory
Attributes (PMAs). Software selects the PMAs for a page by choosing a
PFN from the corresponding physical address range. On these platforms,
this is the only way to allocate noncached memory for use with
noncoherent DMA.

 - Patch 1 adds a new binding to describe physical memory regions in
   the devicetree.
 - Patches 2-6 refactor existing memory type support to be modeled as
   variants on top of Svpbmt.
 - Patches 7-10 add logic to transform the PFN to use the desired alias
   when reading/writing page tables.
 - Patch 11 enables this new method of memory type control on JH7100.

I have boot-tested this series on platforms with each of the 4 ways to
select a memory type: SiFive FU740 (none), QEMU (Svpbmt), Allwinner D1
(XTheadMae), and ESWIN EIC7700 (aliases).


Samuel Holland (11):
  dt-bindings: riscv: Describe physical memory regions
  riscv: mm: Increment PFN in place when splitting mappings
  riscv: mm: Deduplicate pgtable address conversion functions
  riscv: mm: Deduplicate _PAGE_CHG_MASK definition
  riscv: ptdump: Only show N and MT bits when enabled in the kernel
  riscv: mm: Fix up memory types when writing page tables
  riscv: mm: Expose all page table bits to assembly code
  riscv: alternative: Add an ALTERNATIVE_3 macro
  riscv: alternative: Allow calls with alternate link registers
  riscv: mm: Use physical memory aliases to apply PMAs
  riscv: dts: starfive: jh7100: Use physical memory ranges for DMA

 .../bindings/riscv/physical-memory.yaml       | 101 ++++++++++
 arch/riscv/Kconfig                            |   3 +
 arch/riscv/Kconfig.errata                     |  20 +-
 .../boot/dts/starfive/jh7100-common.dtsi      |  30 +--
 arch/riscv/include/asm/alternative-macros.h   |  45 ++++-
 arch/riscv/include/asm/errata_list.h          |  45 -----
 arch/riscv/include/asm/hwcap.h                |   1 +
 arch/riscv/include/asm/pgtable-32.h           |  19 +-
 arch/riscv/include/asm/pgtable-64.h           | 178 ++++++++++--------
 arch/riscv/include/asm/pgtable-bits.h         |  42 ++++-
 arch/riscv/include/asm/pgtable.h              |  55 +++---
 arch/riscv/kernel/alternative.c               |   4 +-
 arch/riscv/kernel/cpufeature.c                |   6 +
 arch/riscv/kernel/setup.c                     |   1 +
 arch/riscv/mm/Makefile                        |   1 +
 arch/riscv/mm/init.c                          |   8 +-
 arch/riscv/mm/kasan_init.c                    |   8 +-
 arch/riscv/mm/memory-alias.S                  | 101 ++++++++++
 arch/riscv/mm/pageattr.c                      |  17 +-
 arch/riscv/mm/pgtable.c                       |  91 +++++++++
 arch/riscv/mm/ptdump.c                        |  19 +-
 include/dt-bindings/riscv/physical-memory.h   |  44 +++++
 22 files changed, 596 insertions(+), 243 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/riscv/physical-memory.yaml
 create mode 100644 arch/riscv/mm/memory-alias.S
 create mode 100644 include/dt-bindings/riscv/physical-memory.h

-- 
2.45.1