[Xen-devel] [PATCH 13/15] xen/arm: p2m: Introduce a new variable removing_mapping in __p2m_set_entry

[Julien Grall]

This is making the code slightly easier to understand.

Signed-off-by: Julien Grall 
---
 xen/arch/arm/p2m.c | 10 ++
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 66d58fabd7..e826f57842 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -792,6 +792,8 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
 unsigned int target = 3 - (page_order / LPAE_SHIFT);
 lpae_t *entry, *table, orig_pte;
 int rc;
+/* A mapping is removed if the MFN is invalid. */
+bool removing_mapping = mfn_eq(smfn, INVALID_MFN);
 
 /* Convenience aliases */
 const unsigned int offsets[4] = {
@@ -817,9 +819,9 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
 {
 /*
  * Don't try to allocate intermediate page table if the mapping
- * is about to be removed (i.e mfn == INVALID_MFN).
+ * is about to be removed.
  */
-rc = p2m_next_level(p2m, mfn_eq(smfn, INVALID_MFN),
+rc = p2m_next_level(p2m, removing_mapping,
 level, &table, offsets[level]);
 if ( rc == GUEST_TABLE_MAP_FAILED )
 {
@@ -830,7 +832,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
  * when removing a mapping as it may not exist in the
  * page table. In this case, just ignore it.
  */
-rc = mfn_eq(smfn, INVALID_MFN) ? 0 : -ENOENT;
+rc = removing_mapping ?  0 : -ENOENT;
 goto out;
 }
 else if ( rc != GUEST_TABLE_NORMAL_PAGE )
@@ -925,7 +927,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
 if ( lpae_is_valid(orig_pte) )
 p2m_remove_pte(entry, p2m->clean_pte);
 
-if ( mfn_eq(smfn, INVALID_MFN) )
+if ( removing_mapping )
 /* Flush can be deferred if the entry is removed */
 p2m->need_flush |= !!lpae_is_valid(orig_pte);
 else
-- 
2.11.0


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Re: [Xen-devel] [PATCH 13/15] xen/arm: p2m: Introduce a new variable removing_mapping in __p2m_set_entry

[Stefano Stabellini]

On Mon, 16 Jul 2018, Julien Grall wrote:
> This is making the code slightly easier to understand.
> 
> Signed-off-by: Julien Grall 

Reviewed-by: Stefano Stabellini 


> ---
>  xen/arch/arm/p2m.c | 10 ++
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 66d58fabd7..e826f57842 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -792,6 +792,8 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
>  unsigned int target = 3 - (page_order / LPAE_SHIFT);
>  lpae_t *entry, *table, orig_pte;
>  int rc;
> +/* A mapping is removed if the MFN is invalid. */
> +bool removing_mapping = mfn_eq(smfn, INVALID_MFN);
>  
>  /* Convenience aliases */
>  const unsigned int offsets[4] = {
> @@ -817,9 +819,9 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
>  {
>  /*
>   * Don't try to allocate intermediate page table if the mapping
> - * is about to be removed (i.e mfn == INVALID_MFN).
> + * is about to be removed.
>   */
> -rc = p2m_next_level(p2m, mfn_eq(smfn, INVALID_MFN),
> +rc = p2m_next_level(p2m, removing_mapping,
>  level, &table, offsets[level]);
>  if ( rc == GUEST_TABLE_MAP_FAILED )
>  {
> @@ -830,7 +832,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
>   * when removing a mapping as it may not exist in the
>   * page table. In this case, just ignore it.
>   */
> -rc = mfn_eq(smfn, INVALID_MFN) ? 0 : -ENOENT;
> +rc = removing_mapping ?  0 : -ENOENT;
>  goto out;
>  }
>  else if ( rc != GUEST_TABLE_NORMAL_PAGE )
> @@ -925,7 +927,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
>  if ( lpae_is_valid(orig_pte) )
>  p2m_remove_pte(entry, p2m->clean_pte);
>  
> -if ( mfn_eq(smfn, INVALID_MFN) )
> +if ( removing_mapping )
>  /* Flush can be deferred if the entry is removed */
>  p2m->need_flush |= !!lpae_is_valid(orig_pte);
>  else
> -- 
> 2.11.0
> 

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