Re: [Xen-devel] [PATCH for-next 13/16] xen/arm: p2m: Fold p2m_tlb_flush into p2m_force_tlb_flush_sync

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 23 Nov 2017, Julien Grall wrote:
> p2m_tlb_flush is called in 2 places: p2m_alloc_table and
> p2m_force_tlb_flush_sync.
> 
> p2m_alloc_table is called when the domain is initialized and could be
> replace by a call to p2m_force_tlb_flush_sync with the P2M write locked.
> 
> This seems a bit pointless but would allow to have a single API for
> flushing and avoid misusage in the P2M code.
> 
> So update p2m_alloc_table to use p2m_force_tlb_flush_sync and fold
> p2m_tlb_flush in p2m_force_tlb_flush_sync.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  xen/arch/arm/p2m.c | 24 +++++++++++-------------
>  1 file changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 37498d8ff1..5294113afe 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -132,11 +132,18 @@ void p2m_restore_state(struct vcpu *n)
>      *last_vcpu_ran = n->vcpu_id;
>  }
>  
> -static void p2m_tlb_flush(struct p2m_domain *p2m)
> +/*
> + * Force a synchronous P2M TLB flush.
> + *
> + * Must be called with the p2m lock held.
> + */
> +static void p2m_force_tlb_flush_sync(struct p2m_domain *p2m)
>  {
>      unsigned long flags = 0;
>      uint64_t ovttbr;
>  
> +    ASSERT(p2m_is_write_locked(p2m));
> +
>      /*
>       * ARM only provides an instruction to flush TLBs for the current
>       * VMID. So switch to the VTTBR of a given P2M if different.
> @@ -157,18 +164,7 @@ static void p2m_tlb_flush(struct p2m_domain *p2m)
>          isb();
>          local_irq_restore(flags);
>      }
> -}
> -
> -/*
> - * Force a synchronous P2M TLB flush.
> - *
> - * Must be called with the p2m lock held.
> - */
> -static void p2m_force_tlb_flush_sync(struct p2m_domain *p2m)
> -{
> -    ASSERT(p2m_is_write_locked(p2m));
>  
> -    p2m_tlb_flush(p2m);
>      p2m->need_flush = false;
>  }
>  
> @@ -1143,7 +1139,9 @@ static int p2m_alloc_table(struct domain *d)
>       * Make sure that all TLBs corresponding to the new VMID are flushed
>       * before using it
>       */
> -    p2m_tlb_flush(p2m);
> +    p2m_write_lock(p2m);
> +    p2m_force_tlb_flush_sync(p2m);
> +    p2m_write_unlock(p2m);
>  
>      return 0;
>  }
> -- 
> 2.11.0
> 

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