Re: [PATCH 1/4] riscv: tlb: fix __p*d_free_tlb()

[Palmer Dabbelt]

On Thu, 04 Jan 2024 02:55:40 PST (-0800), alex@xxxxxxxx wrote:
> On 19/12/2023 18:50, Jisheng Zhang wrote:
> > If non-leaf PTEs I.E pmd, pud or p4d is modified, a sfence.vma is
> > a must for safe, imagine if an implementation caches the non-leaf
> > translation in TLB, although I didn't meet this HW so far, but it's
> > possible in theory.
>
>
> And since this is a fix, it would be worth trying to add a Fixes tag
> here. Not easy I agree because it fixes several commits (I have
> 07037db5d479f,  e8a62cc26ddf5, d10efa21a9374 and c5e9b2c2ae822 if you
> implement tlb_flush() as I suggested).
>
> So I would add the latest commit as the Fixes commit (which would be
> c5e9b2c2ae822), and then I'd send a patch to stable for each commit with
> the right Fixes tag...@Conor: let me know if you have a simpler idea or
> if this is wrong.

I just went with

Fixes: c5e9b2c2ae82 ("riscv: Improve tlb_flush()")
Cc: stable@xxxxxxxxxxxxxxx

hopefully that's fine.  It's still getting tested, it's batched up with 
some other stuff and I managed to find a bad merge so it might take a 
bit...

> Thanks,
>
> Alex
>
>
> > Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
> > ---
> >   arch/riscv/include/asm/pgalloc.h | 20 +++++++++++++++++---
> >   1 file changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
> > index d169a4f41a2e..a12fb83fa1f5 100644
> > --- a/arch/riscv/include/asm/pgalloc.h
> > +++ b/arch/riscv/include/asm/pgalloc.h
> > @@ -95,7 +95,13 @@ static inline void pud_free(struct mm_struct *mm, pud_t *pud)
> >   		__pud_free(mm, pud);
> >   }
> >
> > -#define __pud_free_tlb(tlb, pud, addr)  pud_free((tlb)->mm, pud)
> > +#define __pud_free_tlb(tlb, pud, addr)					\
> > +do {									\
> > +	if (pgtable_l4_enabled) {					\
> > +		pagetable_pud_dtor(virt_to_ptdesc(pud));		\
> > +		tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pud));	\
> > +	}								\
> > +} while (0)
> >
> >   #define p4d_alloc_one p4d_alloc_one
> >   static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr)
> > @@ -124,7 +130,11 @@ static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
> >   		__p4d_free(mm, p4d);
> >   }
> >
> > -#define __p4d_free_tlb(tlb, p4d, addr)  p4d_free((tlb)->mm, p4d)
> > +#define __p4d_free_tlb(tlb, p4d, addr)					\
> > +do {									\
> > +	if (pgtable_l5_enabled)						\
> > +		tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(p4d));	\
> > +} while (0)
> >   #endif /* __PAGETABLE_PMD_FOLDED */
> >
> >   static inline void sync_kernel_mappings(pgd_t *pgd)
> > @@ -149,7 +159,11 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
> >
> >   #ifndef __PAGETABLE_PMD_FOLDED
> >
> > -#define __pmd_free_tlb(tlb, pmd, addr)  pmd_free((tlb)->mm, pmd)
> > +#define __pmd_free_tlb(tlb, pmd, addr)				\
> > +do {								\
> > +	pagetable_pmd_dtor(virt_to_ptdesc(pmd));		\
> > +	tlb_remove_page_ptdesc((tlb), virt_to_ptdesc(pmd));	\
> > +} while (0)
> >
> >   #endif /* __PAGETABLE_PMD_FOLDED */