Re: [PATCH v4 09/16] powerpc/mm: Add new hash_page_mm()

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Michael Neuling <mikey@neuling.org> writes:

> From: Ian Munsie <imunsie@au1.ibm.com>
>
> This adds a new function hash_page_mm() based on the existing hash_page().
> This version allows any struct mm to be passed in, rather than assuming
> current. This is useful for servicing co-processor faults which are not in the
> context of the current running process.
>
> We need to be careful here as the current hash_page() assumes current in a few
> places.

if you move cxl_slbia patch before this, then we could add additonal
information here.

1) We use this to insert hpte entries on-behalf of co-processor.
2) we don't need to flush cpu slb entries when adding new hpte entries
3) We do flush the co-processor slb cache, if adding hpte entry result
in a segement demotion or have mmu_ci_restrictions enabled.
4) We do update the slice array to indicate the new base page size
5) w.r.t co-processor on segment miss we look at slice array and add new slb entry
using newly added copro_calculate_slb "powerpc/cell: Move data segment faulting code out of cell platform"

>
> Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> ---
>  arch/powerpc/include/asm/mmu-hash64.h |  1 +
>  arch/powerpc/mm/hash_utils_64.c       | 24 +++++++++++++++++-------
>  2 files changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
> index aeabd02..764e141 100644
> --- a/arch/powerpc/include/asm/mmu-hash64.h
> +++ b/arch/powerpc/include/asm/mmu-hash64.h
> @@ -324,6 +324,7 @@ extern int __hash_page_64K(unsigned long ea, unsigned long access,
>  			   unsigned int local, int ssize);
>  struct mm_struct;
>  unsigned int hash_page_do_lazy_icache(unsigned int pp, pte_t pte, int trap);
> +extern int hash_page_mm(struct mm_struct *mm, unsigned long ea, unsigned long access, unsigned long trap);
>  extern int hash_page(unsigned long ea, unsigned long access, unsigned long trap);
>  int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
>  		     pte_t *ptep, unsigned long trap, int local, int ssize,
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index bbdb054..698834d 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -904,7 +904,7 @@ void demote_segment_4k(struct mm_struct *mm, unsigned long addr)
>  		return;
>  	slice_set_range_psize(mm, addr, 1, MMU_PAGE_4K);
>  	copro_flush_all_slbs(mm);
> -	if (get_paca_psize(addr) != MMU_PAGE_4K) {
> +	if ((get_paca_psize(addr) != MMU_PAGE_4K) && (current->mm == mm)) {
>  		get_paca()->context = mm->context;
>  		slb_flush_and_rebolt();
>  	}
> @@ -989,12 +989,11 @@ static void check_paca_psize(unsigned long ea, struct mm_struct *mm,
>   * -1 - critical hash insertion error
>   * -2 - access not permitted by subpage protection mechanism
>   */
> -int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> +int hash_page_mm(struct mm_struct *mm, unsigned long ea, unsigned long access, unsigned long trap)
>  {
>  	enum ctx_state prev_state = exception_enter();
>  	pgd_t *pgdir;
>  	unsigned long vsid;
> -	struct mm_struct *mm;
>  	pte_t *ptep;
>  	unsigned hugeshift;
>  	const struct cpumask *tmp;
> @@ -1008,7 +1007,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
>   	switch (REGION_ID(ea)) {
>  	case USER_REGION_ID:
>  		user_region = 1;
> -		mm = current->mm;
>  		if (! mm) {
>  			DBG_LOW(" user region with no mm !\n");
>  			rc = 1;
> @@ -1019,7 +1017,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
>  		vsid = get_vsid(mm->context.id, ea, ssize);
>  		break;
>  	case VMALLOC_REGION_ID:
> -		mm = &init_mm;
>  		vsid = get_kernel_vsid(ea, mmu_kernel_ssize);
>  		if (ea < VMALLOC_END)
>  			psize = mmu_vmalloc_psize;
> @@ -1104,7 +1101,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
>  			WARN_ON(1);
>  		}
>  #endif
> -		check_paca_psize(ea, mm, psize, user_region);
> +		if (current->mm == mm)
> +			check_paca_psize(ea, mm, psize, user_region);
>  
>  		goto bail;
>  	}
> @@ -1145,7 +1143,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
>  		}
>  	}
>  
> -	check_paca_psize(ea, mm, psize, user_region);
> +	if (current->mm == mm)
> +		check_paca_psize(ea, mm, psize, user_region);
>  #endif /* CONFIG_PPC_64K_PAGES */
>  
>  #ifdef CONFIG_PPC_HAS_HASH_64K
> @@ -1180,6 +1179,17 @@ bail:
>  	exception_exit(prev_state);
>  	return rc;
>  }
> +EXPORT_SYMBOL_GPL(hash_page_mm);
> +
> +int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> +{
> +	struct mm_struct *mm = current->mm;
> +
> +	if (REGION_ID(ea) == VMALLOC_REGION_ID)
> +		mm = &init_mm;
> +
> +	return hash_page_mm(mm, ea, access, trap);
> +}
>  EXPORT_SYMBOL_GPL(hash_page);
>  
>  void hash_preload(struct mm_struct *mm, unsigned long ea,
> -- 
> 1.9.1
>
> --
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