| Message ID | 20240626174816.2837278-1-wxjstz@126.com |
|---|---|
| Headers | show |
| Series | Add support for tor type pmp | expand |
On Wed, Jun 26, 2024 at 11:19 PM Xiang W <wxjstz@126.com> wrote: > > Using tor type pmp can save pmp configuration registers in the following > scenarios > > sbi_domain_root_add_memrange(addr, 4M, PAGE_SIZE... > sbi_domain_root_add_memrange(addr + 4M, 512K, PAGE_SIZE... > sbi_domain_root_add_memrange(addr + 4M + 512K, 32K, PAGE_SIZE... This is not true in all cases. For example, if we selectively carve-out a memregion from a DRAM memregion then above approach will result in 3 separate memregions whereas with current overlapping power-of-2 memregions we only need 2 memregions. Allowing arbitrary size of memregions opens a new set of issues. The biggest issues will be dealing which partially overlap (i.e. A overlaps B but A is not inside B and B is not inside A). Currently, we don't have partially overlapping memregions because memregions are power-of-2 size. > > The previous configuration requires 3 sets of pmp configuration registers. > After applying the patch, only 2 sets of pmp configuration registers are > needed. > > Xiang W (3): > lib: sbi: Add tor type PMP support TOR type PMP requires a strict ordering based on addresses so we can't freely re-order memregions. Also, real world RISC-V platforms have implementation specific PMP granularity which will further create problems for TOR type PMP. > lib: sbi: Introduce size to sbi_domain_memregion > lib: sbi: Improve memory region merging > > include/sbi/riscv_asm.h | 6 +- > include/sbi/sbi_domain.h | 37 +++++ > lib/sbi/riscv_asm.c | 190 +++++++++++++--------- > lib/sbi/sbi_domain.c | 336 +++++++++++++++++++++++++-------------- > lib/sbi/sbi_hart.c | 30 ++-- > 5 files changed, 382 insertions(+), 217 deletions(-) > > -- > 2.43.0 > Minimizing the PMP regions is a good thing to have but this can be easily achieved by OpenSBI platform support registering large root memregions at early boot time so that small root memregions registered by drivers will simply get merged into the larger root memregions already registered by platform support. In other words, OpenSBI platform support can minimize PMP regions by pre-registering large memregions. Regards, Anup