Re: [Xen-devel] [PATCH for-next 12/16] xen/arm: p2m: Introduce p2m_tlb_flush_sync, export it and use it

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 23 Nov 2017, Julien Grall wrote:
> Multiple places in the code requires to flush the TLBs wonly when
                                                         ^ only

Aside from this

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> p2m->need_flush is set.
> 
> Rather than open-coding it, introduce a new helper p2m_tlb_flush_sync to
> do it.
> 
> Note that p2m_tlb_flush_sync is exported as it might be used by other
> part of Xen.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> ---
>  xen/arch/arm/p2m.c        | 27 +++++++++++++--------------
>  xen/include/asm-arm/p2m.h |  2 ++
>  2 files changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index d466a5bc43..37498d8ff1 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -52,21 +52,15 @@ static const paddr_t level_masks[] =
>  static const uint8_t level_orders[] =
>      { ZEROETH_ORDER, FIRST_ORDER, SECOND_ORDER, THIRD_ORDER };
>  
> -static void p2m_tlb_flush(struct p2m_domain *p2m);
> -
>  /* Unlock the flush and do a P2M TLB flush if necessary */
>  void p2m_write_unlock(struct p2m_domain *p2m)
>  {
> -    if ( p2m->need_flush )
> -    {
> -        p2m->need_flush = false;
> -        /*
> -         * The final flush is done with the P2M write lock taken to
> -         * to avoid someone else modify the P2M before the TLB
> -         * invalidation has completed.
> -         */
> -        p2m_tlb_flush(p2m);
> -    }
> +    /*
> +     * The final flush is done with the P2M write lock taken to avoid
> +     * someone else modifying the P2M wbefore the TLB invalidation has
> +     * completed.
> +     */
> +    p2m_tlb_flush_sync(p2m);
>  
>      write_unlock(&p2m->lock);
>  }
> @@ -178,6 +172,12 @@ static void p2m_force_tlb_flush_sync(struct p2m_domain 
> *p2m)
>      p2m->need_flush = false;
>  }
>  
> +void p2m_tlb_flush_sync(struct p2m_domain *p2m)
> +{
> +    if ( p2m->need_flush )
> +        p2m_force_tlb_flush_sync(p2m);
> +}
> +
>  /*
>   * Find and map the root page table. The caller is responsible for
>   * unmapping the table.
> @@ -674,8 +674,7 @@ static void p2m_free_entry(struct p2m_domain *p2m,
>       * XXX: Should we defer the free of the page table to avoid the
>       * flush?
>       */
> -    if ( p2m->need_flush )
> -        p2m_force_tlb_flush_sync(p2m);
> +    p2m_tlb_flush_sync(p2m);
>  
>      mfn = _mfn(entry.p2m.base);
>      ASSERT(mfn_valid(mfn));
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index faadcfe8fe..a0abc84ed8 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h
> @@ -204,6 +204,8 @@ static inline int p2m_is_write_locked(struct p2m_domain 
> *p2m)
>      return rw_is_write_locked(&p2m->lock);
>  }
>  
> +void p2m_tlb_flush_sync(struct p2m_domain *p2m);
> +
>  /* Look up the MFN corresponding to a domain's GFN. */
>  mfn_t p2m_lookup(struct domain *d, gfn_t gfn, p2m_type_t *t);

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