Re: [PATCH v7 2/3] arm64/mm: add set_direct_map_ro()

[Xueyuan Chen]

On Tue, Sep 29, 2026 at 10:21 PM Will Deacon <will@xxxxxxxxxx> wrote:
>
> On Tue, Sep 01, 2026 at 11:18:17PM +0800, Xueyuan Chen wrote:
> > Implement set_direct_map_ro() for arm64 and flush the TLB internally.
> >
> > Co-developed-by: Lance Yang <lance.yang@xxxxxxxxx>
> > Signed-off-by: Lance Yang <lance.yang@xxxxxxxxx>
> > Signed-off-by: Xueyuan Chen <xueyuan.chen21@xxxxxxxxx>
> > ---
> >  arch/arm64/include/asm/set_memory.h |  2 ++
> >  arch/arm64/mm/pageattr.c            | 12 ++++++++++++
> >  2 files changed, 14 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm/set_memory.h
> > index 0091ba12200e..1be86dc11543 100644
> > --- a/arch/arm64/include/asm/set_memory.h
> > +++ b/arch/arm64/include/asm/set_memory.h
> > @@ -13,6 +13,8 @@ int set_memory_valid(unsigned long addr, int numpages, int enable);
> >
> >  int set_direct_map_invalid_noflush(struct page *page, unsigned int numpages);
> >  int set_direct_map_default_noflush(struct page *page, unsigned int numpages);
> > +int set_direct_map_ro(struct page *page, unsigned int nr);
> > +#define set_direct_map_ro set_direct_map_ro
> >  bool kernel_page_present(struct page *page);
> >
> >  int set_memory_encrypted(unsigned long addr, int numpages);
> > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
> > index 132938b32eb1..0e95cd904ccb 100644
> > --- a/arch/arm64/mm/pageattr.c
> > +++ b/arch/arm64/mm/pageattr.c
> > @@ -355,6 +355,18 @@ int realm_register_memory_enc_ops(void)
> >       return arm64_mem_crypt_ops_register(&realm_crypt_ops);
> >  }
> >
> > +int set_direct_map_ro(struct page *page, unsigned int nr)
> > +{
> > +     unsigned long addr = (unsigned long)page_address(page);
> > +
> > +     if (!can_set_direct_map())
> > +             return 0;
> > +
> > +     return __change_memory_common(addr, PAGE_SIZE * nr,
> > +                                   __pgprot(PTE_RDONLY),
> > +                                   __pgprot(PTE_WRITE));
> > +}
>
> I haven't quite followed whether or not you intend to send a v8
> making set_memory_ro() handle linear addresses, but fwiw the
> implementation you have here at least looks correct to me, so:
>
> Acked-by: Will Deacon <will@xxxxxxxxxx>

Thanks for taking a look!

>
> Will