linux-kernel - Re: [PATCH v2] riscv: Call secondary mmu notifier when flushing the tlb

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Message-ID: <b40ee162-0b65-4259-a14c-e927a4f90ea6@rivosinc.com>
Date: Wed, 10 Apr 2024 15:30:08 +0200
From: Clément Léger <cleger@...osinc.com>
To: Alexandre Ghiti <alexghiti@...osinc.com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] riscv: Call secondary mmu notifier when flushing the
 tlb



On 28/03/2024 08:38, Alexandre Ghiti wrote:
> This is required to allow the IOMMU driver to correctly flush its own
> TLB.
> 
> Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
> ---
> 
> Changes in v2:
> - Rebase on top of 6.9-rc1
> 
>  arch/riscv/mm/tlbflush.c | 39 +++++++++++++++++++++++----------------
>  1 file changed, 23 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index 893566e004b7..854d984deb07 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -4,6 +4,7 @@
>  #include <linux/smp.h>
>  #include <linux/sched.h>
>  #include <linux/hugetlb.h>
> +#include <linux/mmu_notifier.h>
>  #include <asm/sbi.h>
>  #include <asm/mmu_context.h>
>  
> @@ -99,11 +100,19 @@ static void __ipi_flush_tlb_range_asid(void *info)
>  	local_flush_tlb_range_asid(d->start, d->size, d->stride, d->asid);
>  }
>  
> -static void __flush_tlb_range(struct cpumask *cmask, unsigned long asid,
> +static inline unsigned long get_mm_asid(struct mm_struct *mm)

Hi Alex,

Nit: the inline attribute is probably useless.

> +{
> +	return (mm && static_branch_unlikely(&use_asid_allocator)) ?
> +			atomic_long_read(&mm->context.id) & asid_mask : FLUSH_TLB_NO_ASID;
> +}
> +
> +static void __flush_tlb_range(struct mm_struct *mm,
> +			      struct cpumask *cmask,
>  			      unsigned long start, unsigned long size,
>  			      unsigned long stride)
>  {
>  	struct flush_tlb_range_data ftd;
> +	unsigned long asid = get_mm_asid(mm);
>  	bool broadcast;
>  
>  	if (cpumask_empty(cmask))
> @@ -137,31 +146,26 @@ static void __flush_tlb_range(struct cpumask *cmask, unsigned long asid,
>  
>  	if (cmask != cpu_online_mask)
>  		put_cpu();
> -}
>  
> -static inline unsigned long get_mm_asid(struct mm_struct *mm)
> -{
> -	return static_branch_unlikely(&use_asid_allocator) ?
> -			atomic_long_read(&mm->context.id) & asid_mask : FLUSH_TLB_NO_ASID;
> +	if (mm)
> +		mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, start + size);
>  }
>  
>  void flush_tlb_mm(struct mm_struct *mm)
>  {
> -	__flush_tlb_range(mm_cpumask(mm), get_mm_asid(mm),
> -			  0, FLUSH_TLB_MAX_SIZE, PAGE_SIZE);
> +	__flush_tlb_range(mm, mm_cpumask(mm), 0, FLUSH_TLB_MAX_SIZE, 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_cpumask(mm), get_mm_asid(mm),
> -			  start, end - start, page_size);
> +	__flush_tlb_range(mm, mm_cpumask(mm), start, end - start, page_size);
>  }
>  
>  void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
>  {
> -	__flush_tlb_range(mm_cpumask(vma->vm_mm), get_mm_asid(vma->vm_mm),
> +	__flush_tlb_range(vma->vm_mm, mm_cpumask(vma->vm_mm),
>  			  addr, PAGE_SIZE, PAGE_SIZE);
>  }
>  
> @@ -194,13 +198,13 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
>  		}
>  	}
>  
> -	__flush_tlb_range(mm_cpumask(vma->vm_mm), get_mm_asid(vma->vm_mm),
> +	__flush_tlb_range(vma->vm_mm, mm_cpumask(vma->vm_mm),
>  			  start, end - start, stride_size);
>  }
>  
>  void flush_tlb_kernel_range(unsigned long start, unsigned long end)
>  {
> -	__flush_tlb_range((struct cpumask *)cpu_online_mask, FLUSH_TLB_NO_ASID,
> +	__flush_tlb_range(NULL, (struct cpumask *)cpu_online_mask,
>  			  start, end - start, PAGE_SIZE);
>  }
>  
> @@ -208,7 +212,7 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end)
>  void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
>  			unsigned long end)
>  {
> -	__flush_tlb_range(mm_cpumask(vma->vm_mm), get_mm_asid(vma->vm_mm),
> +	__flush_tlb_range(vma->vm_mm, mm_cpumask(vma->vm_mm),
>  			  start, end - start, PMD_SIZE);
>  }
>  #endif
> @@ -222,7 +226,10 @@ void arch_tlbbatch_add_pending(struct arch_tlbflush_unmap_batch *batch,
>  			       struct mm_struct *mm,
>  			       unsigned long uaddr)
>  {
> +	unsigned long start = uaddr & PAGE_MASK;
> +
>  	cpumask_or(&batch->cpumask, &batch->cpumask, mm_cpumask(mm));
> +	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, start + PAGE_SIZE);
>  }
>  
>  void arch_flush_tlb_batched_pending(struct mm_struct *mm)
> @@ -232,7 +239,7 @@ void arch_flush_tlb_batched_pending(struct mm_struct *mm)
>  
>  void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
>  {
> -	__flush_tlb_range(&batch->cpumask, FLUSH_TLB_NO_ASID, 0,
> -			  FLUSH_TLB_MAX_SIZE, PAGE_SIZE);
> +	__flush_tlb_range(NULL, &batch->cpumask,
> +			  0, FLUSH_TLB_MAX_SIZE, PAGE_SIZE);
>  	cpumask_clear(&batch->cpumask);
>  }

Other than that, looks good to me,

Reviewed-by: Clément Léger <cleger@...osinc.com>

Thanks,

Clément