Hi,
On 12/07/2024 17:22, Oleksii Kurochko wrote:
At least, between Arm and RISC-V most of the code related to Xen page
table handling are common.
This GENERIC_PT code is based on Arm's arm/mmu/pt.c except some minor
changes such as introduction of the following functions:
* get_root_page()
* xen_pt_check_contig()
* set_pte_table_bit()
* sanity_arch_specific_pte_checks()
* get_contig_bit()
* set_pte_permissions()
* flush_xen_tlb_range_va()
It was done because not every functions has the generic pte_flags and
it could be a different positions of the PTE bits in a PTE.
While I am always in favor of trying to avoid code duplication, I am not
sure the page-tables are one that should be.
For instance, you don't have the concept of contiguous page in RISC-V (I
see you introduce dummy flags, but IMHO this is a bit of a hack). All
the code was also written in a way to avoid temporary conflict mappings.
This is to avoid using Break-Before-Make. But on newer hardware this
could be relaxed.
I am interested to know what the others thinks.
Cheers,
--
Julien Grall
