Re: [PATCH v1 6/6] xen/riscv: implement p2m mapping functionality

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 5/20/25 5:16 PM, Jan Beulich wrote:

> On 09.05.2025 17:57, Oleksii Kurochko wrote:
> > These utilities are needed for building and managing RISC-V guest page
> > tables and MMIO mappings by using functions map_regions_p2mt() and
> > guest_physmap_add_entry().
> >
> > To implement p2m mapping functionality the following is introduced:
> > - Define P2M root level/order and entry count.
> > - Introdude radix type for p2m types as it isn't enough free bits in pte
> >   and the helpers (p2m_type_radix_{get,set}()) to deal with them.
> > - Introduce p2m_is_*() helpers() as  pte_is_*() helpers are checking
> >   the valid bit set in the PTE but we have to check p2m_type instead
> >   (look at the comment above p2m_is_valid() for some details).
> >       
> May I suggest to name them at least p2me_is_*() then, as they check entries
> rather than entire P2Ms? Same perhaps elsewhere.
>     
Sure, I will handle that during a work on v2.

> > - Introduce helper to set p2m's pte permission: p2m_set_permissions().
> > - Introduce helper to create p2m entry based on mfn, p2m_type_t and
> >   p2m_access_t.
> > - Introduce helper to generate table entry with correct attributes:
> >   page_to_p2m_table().
> > - Introduce p2m page allocation function: p2m_alloc_page().
> > - Introduce functions to write/remove p2m's entries: p2m_{write,remove}_pte().
> > - Introduce function to allocate p2m table: p2m_create_table().
> > - Introduce functions used to free p2m entry.
> > - Introduce function for table walking: p2m_next_level().
> > - Introduce function to insert an entry in the p2m (p2m_set_entry()).
> > - Introduce superpage splitting: p2m_split_superpage()).
> > - Introduce page table type defines (PGT_{none,writable_page}, etc).
> >
> > Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
> > ---
> >  xen/arch/riscv/include/asm/mm.h   |  32 +-
> >  xen/arch/riscv/include/asm/p2m.h  |  17 +-
> >  xen/arch/riscv/include/asm/page.h |  11 +
> >  xen/arch/riscv/p2m.c              | 780 ++++++++++++++++++++++++++++++
> >  4 files changed, 829 insertions(+), 11 deletions(-)
> >       
> It's imo too many things you do in one go here.
>     
I will split to smaller patches.

Thanks.

~ Oleksii