Re: [PATCH v7 0/2] xen/riscv: introduce identity mapping

[Oleksii <oleksii.kurochko@xxxxxxxxx>]

On Thu, 2023-10-19 at 12:32 +0200, Jan Beulich wrote:
> On 08.08.2023 17:14, Oleksii Kurochko wrote:
> > The patch series introduces things necessary to implement identity
> > mapping:
> >   1. Make identity mapping for the entire Xen.
> >   2. Enable MMU.
> >   3. Jump to the virtual address world
> >   4. Remove identity mapping.
> > 
> > Also current patch series introduces the calculation of physical
> > offset before
> > MMU is enabled as access to physical offset will be calculated
> > wrong after
> > MMU will be enabled because access to phys_off variable is PC-
> > relative and
> > in the case when linker address != load address, it will cause MMU
> > fault.
> > 
> > The reason for this patch series can be found here:
> > https://lore.kernel.org/xen-devel/4e336121-fc0c-b007-bf7b-430352563d55@xxxxxxxxxx/
> > 
> > ---
> > Changes in V7:
> >  - use srli instruction to be consistent with slli instruction in
> > turn_on_mmu()
> > ---
> > Changes in V6:
> >   - Update calc_phys_offset() after rebase.
> >   - Refactor turn_on_mmu() and a way how an argument of
> > turn_on_mmu() is
> >     calculated.
> > ---
> > Changes in V5:
> >         - update the algo of identity mapping removing.
> >         - introduce IDENT_AREA_SIZE.
> >         - introduce turn_on_mmu() function to enable and switch
> > from 1:1 mapping.
> >         - fix typo in PGTBL_INITIAL_COUNT define.
> >         - update the comment above PGTBL_INITIAL_COUNT.
> >         - update prototype of calc_phys_offset(). now it returns
> > phys_offset.
> >         - declare phys_offset as static.
> >         - save returned value of calc_phys_offset to register s2.
> > ---
> > Changes in V4:
> >   - drop patch  [PATCH v3 1/3] xen/riscv: add SPDX tag to config.h
> > as it was
> >     merged to staging
> >   - remove definition of ARRAY_SIZE and ROUNDUP as <xen/macors.h>
> > was introduced where these macros are located now.
> >         - update definition of PGTBL_INITIAL_COUNT
> >         - update the commit message for patch 'xen/riscv: introduce
> > identity mapping'
> >         - update the comments in head.S
> >   - update the algo of identity mapping removing 
> > ---
> > Changes in V3:
> >  - Update the patch series message.
> >  - The following patches were merged to staging so droped from the
> > patch series:
> >    * xen/riscv: add .sbss section to .bss
> >    * xen/riscv: introduce reset_stack() function
> >    * xen/riscv: move extern of cpu0_boot_stack to header
> >    * xen/riscv: add SPDX tags
> >  - move save/restore of a0/a1 registers from patch 4 to patch 2 (
> > numbers are
> >    from the previous patch series version )
> >  - add SPDX tag in config.h
> >  - update definition of PGTBL_INITIAL_COUNT taking into account
> > identity mapping.
> >  - refactor remove_identity_mapping() function.
> >  - add explanatory comments in xen.lds.S and mm.c.
> > ---
> > Changes in V2:
> >  - update the patch series message.
> >  - drop patches from the previous version of the patch series:
> >    * xen/riscv: add __ASSEMBLY__ guards". ( merged )
> >    * xen/riscv: make sure that identity mapping isn't bigger then
> > page size
> >      ( entire Xen is 1:1 mapped so there is no need for the checks
> > from the patch )
> >  - add .sbss.* and put it befor .bss* .
> >  - move out reset_stack() to .text section.
> >  - add '__ro_after_init' for phys_offset variable.
> >  - add '__init' for calc_phys_offset().
> >  - declaring variable phys_off as non static as it will be used in
> > head.S.
> >  - update definition of PGTBL_INITIAL_COUNT and the comment above.
> >  - code style fixes.
> >  - remove id_addrs array becase entire Xen is mapped.
> >  - reverse condition for cycle inside remove_identity_mapping().
> >  - fix page table walk in remove_identity_mapping().
> >  - save hart_id and dtb_addr before call MMU related C functions
> >  - use phys_offset variable instead of doing calcultations to get
> > phys offset
> >    in head.S file. ( it can be easily done as entire Xen is 1:1
> > mapped now )
> >  - declare enable_muu() as __init.
> >  - Update SPDX tags.
> >  - Add Review-By/Suggested-By for some patches.
> >  - code style fixes.
> > 
> > Oleksii Kurochko (2):
> >   xen/riscv: introduce function for physical offset calculation
> >   xen/riscv: introduce identity mapping
> 
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Thanks for Ack.

Should be the patch series re-send with Ack after the end of code
freeze?

~ Oleksii