Re: [PATCH v3 1/4] xen: arm: Add a new helper update_boot_mapping()

[Ayan Kumar Halder <ayankuma@xxxxxxx>]

On 14/08/2024 13:50, Michal Orzel wrote:
> Hi Ayan,
Hi Michal,
> On 13/08/2024 19:13, Ayan Kumar Halder wrote:
> > update_boot_mapping() invokes update_identity_mapping() for the MMU specific
> > code.
> > Later when the MPU code is added, update_boot_mapping() would invoke the
> > equivalent.
> >
> > The common code now invokes update_boot_mapping() instead of
> > update_identity_mapping(). So, that there is clear abstraction between the
> > common and MMU/MPU specific logic.
> >
> > This is in continuation to commit
> > f661a20aa880: "Extract MMU-specific MM code".
> >
> > update_identity_mapping() is now marked as static as it is called within
> > xen/arch/arm/arm64/mmu/mm.c only. Also, updated the prototype to
> > update_boot_mapping() which is now invoked from other files.
> >
> > Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
> > ---
> > Changes from :-
> >
> > v1 - 1. Introduced update_boot_mapping() which invokes
> > update_identity_mapping() in MMU specific code.
> >
> > v2 - 1. Make update_identity_mapping() static and update the prototype.
> >
> >   xen/arch/arm/arm64/mmu/mm.c         | 7 ++++++-
> >   xen/arch/arm/arm64/smpboot.c        | 6 +++---
> >   xen/arch/arm/include/asm/arm64/mm.h | 2 +-
> >   3 files changed, 10 insertions(+), 5 deletions(-)
> >
> > diff --git a/xen/arch/arm/arm64/mmu/mm.c b/xen/arch/arm/arm64/mmu/mm.c
> > index 293acb67e0..1afbbeda5a 100644
> > --- a/xen/arch/arm/arm64/mmu/mm.c
> > +++ b/xen/arch/arm/arm64/mmu/mm.c
> > @@ -111,7 +111,7 @@ void __init arch_setup_page_tables(void)
> >       prepare_runtime_identity_mapping();
> >   }
> >   
> > -void update_identity_mapping(bool enable)
> > +static void update_identity_mapping(bool enable)
> >   {
> >       paddr_t id_addr = virt_to_maddr(_start);
> >       int rc;
> > @@ -125,6 +125,11 @@ void update_identity_mapping(bool enable)
> >       BUG_ON(rc);
> >   }
> >   
> > +void update_boot_mapping(bool enable)
> > +{
> > +    update_identity_mapping(enable);
> > +}
> > +
> >   extern void switch_ttbr_id(uint64_t ttbr);
> >   
> >   typedef void (switch_ttbr_fn)(uint64_t ttbr);
> > diff --git a/xen/arch/arm/arm64/smpboot.c b/xen/arch/arm/arm64/smpboot.c
> > index a225fae64d..789f352ab6 100644
> > --- a/xen/arch/arm/arm64/smpboot.c
> > +++ b/xen/arch/arm/arm64/smpboot.c
> > @@ -112,18 +112,18 @@ int arch_cpu_up(int cpu)
> >       if ( !smp_enable_ops[cpu].prepare_cpu )
> >           return -ENODEV;
> >   
> > -    update_identity_mapping(true);
> > +    update_boot_mapping(true);
> >   
> >       rc = smp_enable_ops[cpu].prepare_cpu(cpu);
> >       if ( rc )
> > -        update_identity_mapping(false);
> > +        update_boot_mapping(false);
> >   
> >       return rc;
> >   }
> >   
> >   void arch_cpu_up_finish(void)
> >   {
> > -    update_identity_mapping(false);
> > +    update_boot_mapping(false);
> >   }
> >   
> >   /*
> > diff --git a/xen/arch/arm/include/asm/arm64/mm.h 
> > b/xen/arch/arm/include/asm/arm64/mm.h
> > index e0bd23a6ed..ac8d1f5c78 100644
> > --- a/xen/arch/arm/include/asm/arm64/mm.h
> > +++ b/xen/arch/arm/include/asm/arm64/mm.h
> > @@ -21,7 +21,7 @@ void arch_setup_page_tables(void);
> >    * Note that nested call (e.g. enable=true, enable=true) is not
> >    * supported.
> >    */
> > -void update_identity_mapping(bool enable);
> > +void update_boot_mapping(bool enable);
> The whole point of adding a wrapper was to avoid ambiguity \wrt identity 
> mapping and MPU.
> You changed the name of a function but left the comment which is pretty MMU 
> specific. I think
> it should be moved to update_identity_mapping.
Yes, you are correct. I will move the comment before

static void update_identity_mapping(bool enable)

{...}

> Apart from that:
> Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
I will keep your R-b

- Ayan