Re: [PATCH v2 00/10] Introduce sv48 support without relocatable kernel

Heiko Stübner
2021-11-24T23:29:38Z

Am Mittwoch, 29. September 2021, 16:51:03 CET schrieb Alexandre Ghiti:
> This patchset allows to have a single kernel for sv39 and sv48 without
> being relocatable.
>
> The idea comes from Arnd Bergmann who suggested to do the same as x86,
> that is mapping the kernel to the end of the address space, which allows
> the kernel to be linked at the same address for both sv39 and sv48 and
> then does not require to be relocated at runtime.
>
> This implements sv48 support at runtime. The kernel will try to
> boot with 4-level page table and will fallback to 3-level if the HW does not
> support it. Folding the 4th level into a 3-level page table has almost no
> cost at runtime.
>
> Tested on:
> - qemu rv64 sv39: OK
> - qemu rv64 sv48: OK
> - qemu rv64 sv39 + kasan: OK
> - qemu rv64 sv48 + kasan: OK
> - qemu rv32: OK
> - Unmatched: OK

On a beagleV (which supports only sv39) I've tested both the limit via
the mmu-type in the devicetree and also that the fallback works when
I disable the mmu-type in the dt, so

Tested-by: Heiko Stuebner <heiko@sntech.de>

>
>
> Changes in v2:
> - Rebase onto for-next
> - Fix KASAN
> - Fix stack canary
> - Get completely rid of MAXPHYSMEM configs
> - Add documentation
>
> Alexandre Ghiti (10):
> riscv: Allow to dynamically define VA_BITS
> riscv: Get rid of MAXPHYSMEM configs
> asm-generic: Prepare for riscv use of pud_alloc_one and pud_free
> riscv: Implement sv48 support
> riscv: Use pgtable_l4_enabled to output mmu_type in cpuinfo
> riscv: Explicit comment about user virtual address space size
> riscv: Improve virtual kernel memory layout dump
> Documentation: riscv: Add sv48 description to VM layout
> riscv: Initialize thread pointer before calling C functions
> riscv: Allow user to downgrade to sv39 when hw supports sv48
>
> Documentation/riscv/vm-layout.rst | 36 ++
> arch/riscv/Kconfig | 35 +-
> arch/riscv/configs/nommu_k210_defconfig | 1 -
> .../riscv/configs/nommu_k210_sdcard_defconfig | 1 -
> arch/riscv/configs/nommu_virt_defconfig | 1 -
> arch/riscv/include/asm/csr.h | 3 +-
> arch/riscv/include/asm/fixmap.h | 1 +
> arch/riscv/include/asm/kasan.h | 2 +-
> arch/riscv/include/asm/page.h | 10 +
> arch/riscv/include/asm/pgalloc.h | 40 +++
> arch/riscv/include/asm/pgtable-64.h | 108 +++++-
> arch/riscv/include/asm/pgtable.h | 30 +-
> arch/riscv/include/asm/sparsemem.h | 6 +-
> arch/riscv/kernel/cpu.c | 23 +-
> arch/riscv/kernel/head.S | 4 +-
> arch/riscv/mm/context.c | 4 +-
> arch/riscv/mm/init.c | 323 +++++++++++++++---
> arch/riscv/mm/kasan_init.c | 91 +++--
> drivers/firmware/efi/libstub/efi-stub.c | 2 +
> include/asm-generic/pgalloc.h | 24 +-
> include/linux/sizes.h | 1 +
> 21 files changed, 615 insertions(+), 131 deletions(-)
>
>