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Subject[RESEND PATCH V3 0/2] riscv: add RISC-V Svpbmt Standard Extension supports
Date
From: Fu Wei <wefu@redhat.com>

This patch follows the RISC-V standard Svpbmt extension in
privilege spec to solve the non-coherent SOC DMA synchronization
issues.

The svpbmt PTE format:
| 63 | 62-61 | 60-8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
N MT RSW D A G U X W R V
^

Of the Reserved bits [63:54] in a leaf PTE, the bits [62:61] are used as
the MT (aka MemType) field. This field specifies one of three memory types
as shown in the following table:
MemType RISC-V Description
---------- ------------------------------------------------
00 - PMA Normal Cacheable, No change to implied PMA memory type
01 - NC Non-cacheable, idempotent, weakly-ordered Main Memory
10 - IO Non-cacheable, non-idempotent, strongly-ordered I/O memory
11 - Rsvd Reserved for future standard use

The standard protection_map[] needn't be modified because the "PMA"
type keeps the highest bits zero.
And the whole modification is limited in the arch/riscv/* and using
a global variable(__riscv_svpbmt) as _PAGE_DMA_MASK/IO/NC for
pgprot_noncached (&writecombine) in pgtable.h.
We also add _PAGE_CHG_MASK to filter PFN than before.

Enable it in devicetree - (Add "mmu-supports-svpbmt" in cpu node)
- mmu-supports-svpbmt

Wei Fu (2):
dt-bindings: riscv: add mmu-supports-svpbmt for Svpbmt
riscv: add RISC-V Svpbmt extension supports

.../devicetree/bindings/riscv/cpus.yaml | 5 +++
arch/riscv/include/asm/fixmap.h | 2 +-
arch/riscv/include/asm/pgtable-64.h | 8 ++--
arch/riscv/include/asm/pgtable-bits.h | 41 ++++++++++++++++++-
arch/riscv/include/asm/pgtable.h | 39 ++++++++++++++----
arch/riscv/kernel/cpufeature.c | 32 +++++++++++++++
arch/riscv/mm/init.c | 5 +++
7 files changed, 117 insertions(+), 15 deletions(-)

--
2.25.4

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