[PATCHv3 0/5] use __create_pgd_mapping() to implement idmap and unify codes

[Pingfan Liu]

v2 -> v3:
  -1. leave out the part of redefinition the CONFIG_PGTABLE_LEVEL,
concentrate on sharing __create_pgd_mapping() in head.S as the first
step.
  -2. make IDMAP_PGTABLE_LEVELS use the max value ([3/5])

rfc -> v2:
  more debug and test

*** Goal of this series ***

__create_pgd_mapping() sets up the pgtable for mapping __va(paddr) ->
paddr under the MMU-on situation.  Since pgtable upper level holds the
paddr of the lower level, with a slight adaptation,
__create_pgd_mapping() can also set up the mapping under the MMU-off
situation. ([4/5])

After that, both idmap_pg_dir and init_pg_dir can be created by
__create_pgd_mapping(). And the counterpart asm code can be simplified.

This series can be applied against commit 4284bdf9405a ("Linux 5.13-rc2").


*** Plan for the next ***

The omitted part in V2, which resorts to redefinition of
CONFIG_PGTABLE_LEVEL to provides two sets of routines. One set is proper
to set up a idmap which can adress total system RAM.  That can simplify
the asm code in head.S furtherly, also provide an create_idmap() API.


*** Test ***

This series can success booting with the following configuration on either Cavium
ThunderX2 99xx or Qualcomm Falkor:
            PAGE_SIZE  VA  PA  PGTABLE_LEVEL
Qualcomm    4K         48  48  4
            4K         39  48  3
            16K        48  48  4
            16K        47  48  3
Cavium      64K        52  52  3
            64K        48  52  3
            64K        42  52  2



*** History ***

RFC:
https://lore.kernel.org/linux-arm-kernel/20210410095654.24102-1-kernelfans@gmail.com/
V2:
https://lore.kernel.org/linux-arm-kernel/20210425141304.32721-1-kernelfans@gmail.com/


Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Ard Biesheuvel <ardb at kernel.org>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Kristina Martsenko <kristina.martsenko at arm.com>
Cc: James Morse <james.morse at arm.com>
Cc: Steven Price <steven.price at arm.com>
Cc: Jonathan Cameron <Jonathan.Cameron at huawei.com>
Cc: Pavel Tatashin <pasha.tatashin at soleen.com>
Cc: Anshuman Khandual <anshuman.khandual at arm.com>
Cc: Atish Patra <atish.patra at wdc.com>
Cc: Mike Rapoport <rppt at kernel.org>
Cc: Logan Gunthorpe <logang at deltatee.com>
Cc: Mark Brown <broonie at kernel.org>
To: linux-arm-kernel at lists.infradead.org

Pingfan Liu (5):
  arm64/mm: introduce pgtable allocator for idmap_pg_dir and init_pg_dir
  arm64/mm: disable WARN_ON() and BUG_ON() in __create_pgd_mapping() if
    too early
  arm64/mm: unconditionally set IDMAP_PGTABLE_LEVELS to max pgtable
    level
  arm64/mm: make __create_pgd_mapping() capable to handle pgtable's
    paddr
  arm64/mm: use __create_pgd_mapping() to create pgtable for
    idmap_pg_dir and init_pg_dir

 arch/arm64/include/asm/kernel-pgtable.h |  33 +++--
 arch/arm64/include/asm/pgalloc.h        |   9 ++
 arch/arm64/kernel/head.S                | 164 +++++++-----------------
 arch/arm64/mm/mmu.c                     | 108 ++++++++++++----
 4 files changed, 153 insertions(+), 161 deletions(-)

-- 
2.29.2