Currently kernel_page_present() function doesn't support huge page
detection causes the function to mistakenly return false to the
hibernation core.

Add huge page detection to the function to solve the problem.

Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
---
 arch/riscv/mm/pageattr.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index 86c56616e5de..792b8d10cdfc 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
 	p4d = p4d_offset(pgd, addr);
 	if (!p4d_present(*p4d))
 		return false;
+	if (p4d_leaf(*p4d))
+		return true;
 
 	pud = pud_offset(p4d, addr);
 	if (!pud_present(*pud))
 		return false;
+	if (pud_leaf(*pud))
+		return true;
 
 	pmd = pmd_offset(pud, addr);
 	if (!pmd_present(*pmd))
 		return false;
+	if (pmd_leaf(*pmd))
+		return true;
 
 	pte = pte_offset_kernel(pmd, addr);
 	return pte_present(*pte);
-- 
2.34.1

+CC Alex

On Fri, Jan 27, 2023 at 05:10:50PM +0800, Sia Jee Heng wrote:
> Currently kernel_page_present() function doesn't support huge page
> detection causes the function to mistakenly return false to the
> hibernation core.

This sounds like a bug & should have a fixes tag, no? I assume for
whatever commit enabled huge page support...
We don't support set_memory, which by the looks of things is the other
usecase for this function, so probably doesn't need backporting.

Alex, does this change look good to you?

> Add huge page detection to the function to solve the problem.
> 
> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> ---
>  arch/riscv/mm/pageattr.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> index 86c56616e5de..792b8d10cdfc 100644
> --- a/arch/riscv/mm/pageattr.c
> +++ b/arch/riscv/mm/pageattr.c
> @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
>  	p4d = p4d_offset(pgd, addr);
>  	if (!p4d_present(*p4d))
>  		return false;
> +	if (p4d_leaf(*p4d))
> +		return true;
>  
>  	pud = pud_offset(p4d, addr);
>  	if (!pud_present(*pud))
>  		return false;
> +	if (pud_leaf(*pud))
> +		return true;
>  
>  	pmd = pmd_offset(pud, addr);
>  	if (!pmd_present(*pmd))
>  		return false;
> +	if (pmd_leaf(*pmd))
> +		return true;
>  
>  	pte = pte_offset_kernel(pmd, addr);
>  	return pte_present(*pte);
> -- 
> 2.34.1
> 

Hi,

On Mon, Jan 30, 2023 at 10:57 PM Conor Dooley <conor@kernel.org> wrote:
>
> +CC Alex
>
> On Fri, Jan 27, 2023 at 05:10:50PM +0800, Sia Jee Heng wrote:
> > Currently kernel_page_present() function doesn't support huge page
> > detection causes the function to mistakenly return false to the
> > hibernation core.
>
> This sounds like a bug & should have a fixes tag, no? I assume for
> whatever commit enabled huge page support...
> We don't support set_memory, which by the looks of things is the other
> usecase for this function, so probably doesn't need backporting.

Maybe add this patch in the Fixes tag: commit 9e953cda5cdf ("riscv:
Introduce huge page support for 32/64bit kernel").

>
> Alex, does this change look good to you?

Yes, just one thing though: what about a pgd_leaf() test? Even if very
unlikely (I see x86 does not even test it), the privileged spec states
it is possible to have a 256TB page.

Thanks,

Alex

>
> > Add huge page detection to the function to solve the problem.
> >
> > Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> > Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> > Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> > ---
> >  arch/riscv/mm/pageattr.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> > index 86c56616e5de..792b8d10cdfc 100644
> > --- a/arch/riscv/mm/pageattr.c
> > +++ b/arch/riscv/mm/pageattr.c
> > @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
> >       p4d = p4d_offset(pgd, addr);
> >       if (!p4d_present(*p4d))
> >               return false;
> > +     if (p4d_leaf(*p4d))
> > +             return true;
> >
> >       pud = pud_offset(p4d, addr);
> >       if (!pud_present(*pud))
> >               return false;
> > +     if (pud_leaf(*pud))
> > +             return true;
> >
> >       pmd = pmd_offset(pud, addr);
> >       if (!pmd_present(*pmd))
> >               return false;
> > +     if (pmd_leaf(*pmd))
> > +             return true;
> >
> >       pte = pte_offset_kernel(pmd, addr);
> >       return pte_present(*pte);
> > --
> > 2.34.1
> >

> -----Original Message-----
> From: Alexandre Ghiti <alexghiti@rivosinc.com>
> Sent: Tuesday, 31 January, 2023 4:19 PM
> To: Conor Dooley <conor@kernel.org>
> Cc: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu; linux-
> riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v3 3/4] RISC-V: mm: Enable huge page support to kernel_page_present() function
> 
> Hi,
> 
> On Mon, Jan 30, 2023 at 10:57 PM Conor Dooley <conor@kernel.org> wrote:
> >
> > +CC Alex
> >
> > On Fri, Jan 27, 2023 at 05:10:50PM +0800, Sia Jee Heng wrote:
> > > Currently kernel_page_present() function doesn't support huge page
> > > detection causes the function to mistakenly return false to the
> > > hibernation core.
> >
> > This sounds like a bug & should have a fixes tag, no? I assume for
> > whatever commit enabled huge page support...
> > We don't support set_memory, which by the looks of things is the other
> > usecase for this function, so probably doesn't need backporting.
> 
> Maybe add this patch in the Fixes tag: commit 9e953cda5cdf ("riscv:
> Introduce huge page support for 32/64bit kernel").
Sure, will add the fixes tag.
> 
> >
> > Alex, does this change look good to you?
> 
> Yes, just one thing though: what about a pgd_leaf() test? Even if very
> unlikely (I see x86 does not even test it), the privileged spec states
> it is possible to have a 256TB page.
I can add it in. But as you are probably aware that x86 and ARM don't even tested it. Thanks.
> 
> Thanks,
> 
> Alex
> 
> >
> > > Add huge page detection to the function to solve the problem.
> > >
> > > Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> > > Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> > > Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> > > ---
> > >  arch/riscv/mm/pageattr.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> > > index 86c56616e5de..792b8d10cdfc 100644
> > > --- a/arch/riscv/mm/pageattr.c
> > > +++ b/arch/riscv/mm/pageattr.c
> > > @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
> > >       p4d = p4d_offset(pgd, addr);
> > >       if (!p4d_present(*p4d))
> > >               return false;
> > > +     if (p4d_leaf(*p4d))
> > > +             return true;
> > >
> > >       pud = pud_offset(p4d, addr);
> > >       if (!pud_present(*pud))
> > >               return false;
> > > +     if (pud_leaf(*pud))
> > > +             return true;
> > >
> > >       pmd = pmd_offset(pud, addr);
> > >       if (!pmd_present(*pmd))
> > >               return false;
> > > +     if (pmd_leaf(*pmd))
> > > +             return true;
> > >
> > >       pte = pte_offset_kernel(pmd, addr);
> > >       return pte_present(*pte);
> > > --
> > > 2.34.1
> > >