Re: [Xen-devel] [For Xen-4.10 Resend PATCH 1/3] Allow control of icache invalidations when calling flush_page_to_ram()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 15 May 2017, Punit Agrawal wrote:
> flush_page_to_ram() unconditionally drops the icache. In certain
> situations this leads to execessive icache flushes when
> flush_page_to_ram() ends up being repeatedly called in a loop.
> 
> Introduce a parameter to allow callers of flush_page_to_ram() to take
> responsibility of synchronising the icache. This is in preparations for
> adding logic to make the callers perform the necessary icache
> maintenance operations.
> 
> Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

> ---
>  xen/arch/arm/mm.c              | 5 +++--
>  xen/arch/arm/p2m.c             | 2 +-
>  xen/common/page_alloc.c        | 2 +-
>  xen/include/asm-arm/page.h     | 2 +-
>  xen/include/asm-x86/flushtlb.h | 2 +-
>  5 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 48f74f6e65..082c872c72 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -420,7 +420,7 @@ unsigned long domain_page_map_to_mfn(const void *ptr)
>  }
>  #endif
>  
> -void flush_page_to_ram(unsigned long mfn)
> +void flush_page_to_ram(unsigned long mfn, bool sync_icache)
>  {
>      void *v = map_domain_page(_mfn(mfn));
>  
> @@ -435,7 +435,8 @@ void flush_page_to_ram(unsigned long mfn)
>       * I-Cache (See D4.9.2 in ARM DDI 0487A.k_iss10775). Instead of using 
> flush
>       * by VA on select platforms, we just flush the entire cache here.
>       */
> -    invalidate_icache();
> +    if ( sync_icache )
> +        invalidate_icache();
>  }
>  
>  void __init arch_init_memory(void)
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 34d57760d7..29f2e2fad3 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1392,7 +1392,7 @@ int p2m_cache_flush(struct domain *d, gfn_t start, 
> unsigned long nr)
>          /* XXX: Implement preemption */
>          while ( gfn_x(start) < gfn_x(next_gfn) )
>          {
> -            flush_page_to_ram(mfn_x(mfn));
> +            flush_page_to_ram(mfn_x(mfn), true);
>  
>              start = gfn_add(start, 1);
>              mfn = mfn_add(mfn, 1);
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index 9e41fb4cd3..eba78f1a3d 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -833,7 +833,7 @@ static struct page_info *alloc_heap_pages(
>          /* Ensure cache and RAM are consistent for platforms where the
>           * guest can control its own visibility of/through the cache.
>           */
> -        flush_page_to_ram(page_to_mfn(&pg[i]));
> +        flush_page_to_ram(page_to_mfn(&pg[i]), true);
>      }
>  
>      spin_unlock(&heap_lock);
> diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> index 4b46e8831c..497b4c86ad 100644
> --- a/xen/include/asm-arm/page.h
> +++ b/xen/include/asm-arm/page.h
> @@ -407,7 +407,7 @@ static inline void flush_xen_data_tlb_range_va(unsigned 
> long va,
>  }
>  
>  /* Flush the dcache for an entire page. */
> -void flush_page_to_ram(unsigned long mfn);
> +void flush_page_to_ram(unsigned long mfn, bool sync_icache);
>  
>  /*
>   * Print a walk of a page table or p2m
> diff --git a/xen/include/asm-x86/flushtlb.h b/xen/include/asm-x86/flushtlb.h
> index 8b7adef7c5..bd2be7e482 100644
> --- a/xen/include/asm-x86/flushtlb.h
> +++ b/xen/include/asm-x86/flushtlb.h
> @@ -118,7 +118,7 @@ void flush_area_mask(const cpumask_t *, const void *va, 
> unsigned int flags);
>  #define flush_tlb_one_all(v)                    \
>      flush_tlb_one_mask(&cpu_online_map, v)
>  
> -static inline void flush_page_to_ram(unsigned long mfn) {}
> +static inline void flush_page_to_ram(unsigned long mfn, bool sync_icache) {}
>  static inline int invalidate_dcache_va_range(const void *p,
>                                               unsigned long size)
>  { return -EOPNOTSUPP; }
> -- 
> 2.11.0
> 

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