Re: [PATCH 6.6 085/121] riscv: Improve tlb_flush()

[Samuel Holland <samuel.holland@sifive.com>]

On 2024-02-13 11:21 AM, Greg Kroah-Hartman wrote:
> 6.6-stable review patch.  If anyone has any objections, please let me know.

This patch has a bug that was fixed in 97cf301fa42e ("riscv: Flush the tlb when
a page directory is freed"), so that fix should be backported as well.

Regards,
Samuel

> ------------------
> 
> From: Alexandre Ghiti <alexghiti@rivosinc.com>
> 
> [ Upstream commit c5e9b2c2ae82231d85d9650854e7b3e97dde33da ]
> 
> For now, tlb_flush() simply calls flush_tlb_mm() which results in a
> flush of the whole TLB. So let's use mmu_gather fields to provide a more
> fine-grained flush of the TLB.
> 
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> # On RZ/Five SMARC
> Link: https://lore.kernel.org/r/20231030133027.19542-2-alexghiti@rivosinc.com
> Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
> Stable-dep-of: d9807d60c145 ("riscv: mm: execute local TLB flush after populating vmemmap")
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>  arch/riscv/include/asm/tlb.h      | 8 +++++++-
>  arch/riscv/include/asm/tlbflush.h | 3 +++
>  arch/riscv/mm/tlbflush.c          | 7 +++++++
>  3 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/include/asm/tlb.h b/arch/riscv/include/asm/tlb.h
> index 120bcf2ed8a8..1eb5682b2af6 100644
> --- a/arch/riscv/include/asm/tlb.h
> +++ b/arch/riscv/include/asm/tlb.h
> @@ -15,7 +15,13 @@ static void tlb_flush(struct mmu_gather *tlb);
>  
>  static inline void tlb_flush(struct mmu_gather *tlb)
>  {
> -	flush_tlb_mm(tlb->mm);
> +#ifdef CONFIG_MMU
> +	if (tlb->fullmm || tlb->need_flush_all)
> +		flush_tlb_mm(tlb->mm);
> +	else
> +		flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end,
> +				   tlb_get_unmap_size(tlb));
> +#endif
>  }
>  
>  #endif /* _ASM_RISCV_TLB_H */
> diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
> index a09196f8de68..f5c4fb0ae642 100644
> --- a/arch/riscv/include/asm/tlbflush.h
> +++ b/arch/riscv/include/asm/tlbflush.h
> @@ -32,6 +32,8 @@ static inline void local_flush_tlb_page(unsigned long addr)
>  #if defined(CONFIG_SMP) && defined(CONFIG_MMU)
>  void flush_tlb_all(void);
>  void flush_tlb_mm(struct mm_struct *mm);
> +void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
> +			unsigned long end, unsigned int page_size);
>  void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr);
>  void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
>  		     unsigned long end);
> @@ -52,6 +54,7 @@ static inline void flush_tlb_range(struct vm_area_struct *vma,
>  }
>  
>  #define flush_tlb_mm(mm) flush_tlb_all()
> +#define flush_tlb_mm_range(mm, start, end, page_size) flush_tlb_all()
>  #endif /* !CONFIG_SMP || !CONFIG_MMU */
>  
>  /* Flush a range of kernel pages */
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index 77be59aadc73..fa03289853d8 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -132,6 +132,13 @@ void flush_tlb_mm(struct mm_struct *mm)
>  	__flush_tlb_range(mm, 0, -1, PAGE_SIZE);
>  }
>  
> +void flush_tlb_mm_range(struct mm_struct *mm,
> +			unsigned long start, unsigned long end,
> +			unsigned int page_size)
> +{
> +	__flush_tlb_range(mm, start, end - start, page_size);
> +}
> +
>  void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
>  {
>  	__flush_tlb_range(vma->vm_mm, addr, PAGE_SIZE, PAGE_SIZE);