[v1,0/6] Unflattening and relocation of host device tree

Message

Oleksii Kurochko Nov. 27, 2024, 12:50 p.m. UTC

The current patch series introduces the relocation of the host device tree file
to free up low memory and also it is expected that discard_initial_modules()
will be called sooner or later, it will discard the FDT boot module,
and remove_early_mappings() will destroy the early mappings.

In addition to relocation, unflattening is introduced to create the tree of
struct device_node for the host device tree.

To implement this, several things have been introduced:
 - destroy_xen_mappings() function, which removes page mappings from Xen's
   page tables. This is necessary for clear_fixmap().
 - {set,clear}_fixmap() functions to manage mappings in the fixmap region,
   which are expected to be used in copy_from_paddr() to copy the FDT to Xen's
   heap.
 - A new config HAS_CMO is introduced (in anticipation of future use). This is
   despite the fact that hardware ( "available" to me ) with the hypervisor
   extension is generally I/O-coherent ( and it is preferred way mentioned in
   the RISC-V spec ) and should not be an issue in QEMU as it doesn't emulate
   caches.
   This config introduces stubs for clean_and_invalidate_dcache_va_range()
   and clean_dcache_va_range(), which are expected to be used in
   copy_from_paddr() and flush_page_to_ram(), which in turn are expected to be
   used during the call to xmalloc_bytes() in relocate_fdt().
 - The introduction of copy_from_paddr() to copy the FDT to an address
   allocated in Xen's heap.

Oleksii Kurochko (6):
  xen/riscv: add destroy_xen_mappings() to remove mappings in Xen page
    tables
  xen/riscv: reorder includes in asm/page.h alphabetically
  xen/riscv: add {set,clear}_fixmap() functions for managing fixmap
    entries
  xen/riscv: introduce cache management operations (CMO)
  xen/riscv: implement relocate_fdt()
  xen/riscv: relocating and unflattening host device tree

 xen/arch/riscv/Kconfig              |  3 ++
 xen/arch/riscv/include/asm/fixmap.h |  5 +++
 xen/arch/riscv/include/asm/mm.h     | 10 ++++-
 xen/arch/riscv/include/asm/page.h   | 30 +++++++++++++--
 xen/arch/riscv/mm.c                 |  9 ++---
 xen/arch/riscv/pt.c                 | 27 ++++++++++++++
 xen/arch/riscv/setup.c              | 57 ++++++++++++++++++++++++++++-
 7 files changed, 128 insertions(+), 13 deletions(-)