Re: [Xen-devel] [PATCH 13/22] xen/arm: p2m: Introduce p2m_{read, write}_{, un}lock helpers

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 20 Jul 2016, Julien Grall wrote:
> Some functions in the p2m code do not require to modify the P2M code.
> Document it by introducing separate helpers to lock the p2m.
> 
> This patch does not change the lock. This will be done in a subsequent
> patch.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


>  xen/arch/arm/p2m.c | 49 +++++++++++++++++++++++++++++++++++++------------
>  1 file changed, 37 insertions(+), 12 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 4c279dc..d74c249 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -47,11 +47,36 @@ static bool_t p2m_mapping(lpae_t pte)
>      return p2m_valid(pte) && !pte.p2m.table;
>  }
>  
> +static inline void p2m_write_lock(struct p2m_domain *p2m)
> +{
> +    spin_lock(&p2m->lock);
> +}
> +
> +static inline void p2m_write_unlock(struct p2m_domain *p2m)
> +{
> +    spin_unlock(&p2m->lock);
> +}
> +
> +static inline void p2m_read_lock(struct p2m_domain *p2m)
> +{
> +    spin_lock(&p2m->lock);
> +}
> +
> +static inline void p2m_read_unlock(struct p2m_domain *p2m)
> +{
> +    spin_unlock(&p2m->lock);
> +}
> +
> +static inline int p2m_is_locked(struct p2m_domain *p2m)
> +{
> +    return spin_is_locked(&p2m->lock);
> +}
> +
>  void p2m_dump_info(struct domain *d)
>  {
>      struct p2m_domain *p2m = &d->arch.p2m;
>  
> -    spin_lock(&p2m->lock);
> +    p2m_read_lock(p2m);
>      printk("p2m mappings for domain %d (vmid %d):\n",
>             d->domain_id, p2m->vmid);
>      BUG_ON(p2m->stats.mappings[0] || p2m->stats.shattered[0]);
> @@ -60,7 +85,7 @@ void p2m_dump_info(struct domain *d)
>      printk("  2M mappings: %ld (shattered %ld)\n",
>             p2m->stats.mappings[2], p2m->stats.shattered[2]);
>      printk("  4K mappings: %ld\n", p2m->stats.mappings[3]);
> -    spin_unlock(&p2m->lock);
> +    p2m_read_unlock(p2m);
>  }
>  
>  void memory_type_changed(struct domain *d)
> @@ -166,7 +191,7 @@ static mfn_t __p2m_lookup(struct domain *d, gfn_t gfn, 
> p2m_type_t *t)
>      p2m_type_t _t;
>      unsigned int level, root_table;
>  
> -    ASSERT(spin_is_locked(&p2m->lock));
> +    ASSERT(p2m_is_locked(p2m));
>      BUILD_BUG_ON(THIRD_MASK != PAGE_MASK);
>  
>      /* Allow t to be NULL */
> @@ -233,9 +258,9 @@ mfn_t p2m_lookup(struct domain *d, gfn_t gfn, p2m_type_t 
> *t)
>      mfn_t ret;
>      struct p2m_domain *p2m = &d->arch.p2m;
>  
> -    spin_lock(&p2m->lock);
> +    p2m_read_lock(p2m);
>      ret = __p2m_lookup(d, gfn, t);
> -    spin_unlock(&p2m->lock);
> +    p2m_read_unlock(p2m);
>  
>      return ret;
>  }
> @@ -476,7 +501,7 @@ static int __p2m_get_mem_access(struct domain *d, gfn_t 
> gfn,
>  #undef ACCESS
>      };
>  
> -    ASSERT(spin_is_locked(&p2m->lock));
> +    ASSERT(p2m_is_locked(p2m));
>  
>      /* If no setting was ever set, just return rwx. */
>      if ( !p2m->mem_access_enabled )
> @@ -945,7 +970,7 @@ static int apply_p2m_changes(struct domain *d,
>       */
>      flush_pt = iommu_enabled && !iommu_has_feature(d, 
> IOMMU_FEAT_COHERENT_WALK);
>  
> -    spin_lock(&p2m->lock);
> +    p2m_write_lock(p2m);
>  
>      /* Static mapping. P2M_ROOT_PAGES > 1 are handled below */
>      if ( P2M_ROOT_PAGES == 1 )
> @@ -1149,7 +1174,7 @@ out:
>              unmap_domain_page(mappings[level]);
>      }
>  
> -    spin_unlock(&p2m->lock);
> +    p2m_write_unlock(p2m);
>  
>      if ( rc < 0 && ( op == INSERT ) &&
>           addr != start_gpaddr )
> @@ -1530,7 +1555,7 @@ struct page_info *get_page_from_gva(struct vcpu *v, 
> vaddr_t va,
>      if ( v != current )
>          return NULL;
>  
> -    spin_lock(&p2m->lock);
> +    p2m_read_lock(p2m);
>  
>      rc = gvirt_to_maddr(va, &maddr, flags);
>  
> @@ -1550,7 +1575,7 @@ err:
>      if ( !page && p2m->mem_access_enabled )
>          page = p2m_mem_access_check_and_get_page(va, flags);
>  
> -    spin_unlock(&p2m->lock);
> +    p2m_read_unlock(p2m);
>  
>      return page;
>  }
> @@ -1824,9 +1849,9 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn,
>      int ret;
>      struct p2m_domain *p2m = p2m_get_hostp2m(d);
>  
> -    spin_lock(&p2m->lock);
> +    p2m_read_lock(p2m);
>      ret = __p2m_get_mem_access(d, gfn, access);
> -    spin_unlock(&p2m->lock);
> +    p2m_read_unlock(p2m);
>  
>      return ret;
>  }
> -- 
> 1.9.1
> 

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