Re: [Xen-devel] [RFC 07/16] xen/arm: p2m: Introduce p2m_is_valid and use it

2018-11-02 Thread Stefano Stabellini 
On Tue, 30 Oct 2018, Julien Grall wrote:
> Hi,
> 
> On 30/10/2018 00:21, Stefano Stabellini wrote:
> > On Mon, 8 Oct 2018, Julien Grall wrote:
> > > The LPAE format allows to store information in an entry even with the
> > > valid bit unset. In a follow-up patch, we will take advantage of this
> > > feature to re-purpose the valid bit for generating a translation fault
> > > even if an entry contains valid information.
> > > 
> > > So we need a different way to know whether an entry contains valid
> > > information. It is possible to use the information hold in the p2m_type
> > > to know for that purpose. Indeed all entries containing valid
> > > information will have a valid p2m type (i.e p2m_type != p2m_invalid).
> > > 
> > > This patch introduces a new helper p2m_is_valid, which implements that
> > > idea, and replace most of lpae_is_valid call with the new helper. The ones
> > > remaining are for TLBs handling and entries accounting.
> > > 
> > > With the renaming there are 2 others changes required:
> > >  - Generate table entry with a valid p2m type
> > >  - Detect new mapping for proper stats accounting
> > > 
> > > Signed-off-by: Julien Grall 
> > > ---
> > >   xen/arch/arm/p2m.c | 34 +++---
> > >   1 file changed, 23 insertions(+), 11 deletions(-)
> > > 
> > > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > > index 6c76298ebc..2a1e7e9be2 100644
> > > --- a/xen/arch/arm/p2m.c
> > > +++ b/xen/arch/arm/p2m.c
> > > @@ -220,17 +220,26 @@ static p2m_access_t p2m_mem_access_radix_get(struct
> > > p2m_domain *p2m, gfn_t gfn)
> > >   }
> > > /*
> > > + * In the case of the P2M, the valid bit is used for other purpose. Use
> > > + * the type to check whether an entry is valid.
> > > + */
> > > +static inline bool p2m_is_valid(lpae_t pte)
> > > +{
> > > +return pte.p2m.type != p2m_invalid;
> > > +}
> > > +
> > > +/*
> > >* lpae_is_* helpers don't check whether the valid bit is set in the
> > >* PTE. Provide our own overlay to check the valid bit.
> > >*/
> > >   static inline bool p2m_is_mapping(lpae_t pte, unsigned int level)
> > >   {
> > > -return lpae_is_valid(pte) && lpae_is_mapping(pte, level);
> > > +return p2m_is_valid(pte) && lpae_is_mapping(pte, level);
> > >   }
> > > static inline bool p2m_is_superpage(lpae_t pte, unsigned int level)
> > >   {
> > > -return lpae_is_valid(pte) && lpae_is_superpage(pte, level);
> > > +return p2m_is_valid(pte) && lpae_is_superpage(pte, level);
> > >   }
> > > #define GUEST_TABLE_MAP_FAILED 0
> > > @@ -264,7 +273,7 @@ static int p2m_next_level(struct p2m_domain *p2m, bool
> > > read_only,
> > > entry = *table + offset;
> > >   -if ( !lpae_is_valid(*entry) )
> > > +if ( !p2m_is_valid(*entry) )
> > >   {
> > >   if ( read_only )
> > >   return GUEST_TABLE_MAP_FAILED;
> > > @@ -356,7 +365,7 @@ mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
> > > entry = table[offsets[level]];
> > >   -if ( lpae_is_valid(entry) )
> > > +if ( p2m_is_valid(entry) )
> > >   {
> > >   *t = entry.p2m.type;
> > >   @@ -544,8 +553,11 @@ static lpae_t page_to_p2m_table(struct page_info
> > > *page)
> > >   /*
> > >* The access value does not matter because the hardware will ignore
> > >* the permission fields for table entry.
> > > + *
> > > + * We use p2m_ram_rw so the entry has a valid type. This is important
> > > + * for p2m_is_valid() to return valid on table entries.
> > >*/
> > > -return mfn_to_p2m_entry(page_to_mfn(page), p2m_invalid,
> > > p2m_access_rwx);
> > > +return mfn_to_p2m_entry(page_to_mfn(page), p2m_ram_rw,
> > > p2m_access_rwx);
> > >   }
> > > static inline void p2m_write_pte(lpae_t *p, lpae_t pte, bool
> > > clean_pte)
> > > @@ -569,7 +581,7 @@ static int p2m_create_table(struct p2m_domain *p2m,
> > > lpae_t *entry)
> > >   struct page_info *page;
> > >   lpae_t *p;
> > >   -ASSERT(!lpae_is_valid(*entry));
> > > +ASSERT(!p2m_is_valid(*entry));
> > > page = alloc_domheap_page(NULL, 0);
> > >   if ( page == NULL )
> > > @@ -626,7 +638,7 @@ static int p2m_mem_access_radix_set(struct p2m_domain
> > > *p2m, gfn_t gfn,
> > >*/
> > >   static void p2m_put_l3_page(const lpae_t pte)
> > >   {
> > > -ASSERT(lpae_is_valid(pte));
> > > +ASSERT(p2m_is_valid(pte));
> > > /*
> > >* TODO: Handle other p2m types
> > > @@ -654,11 +666,11 @@ static void p2m_free_entry(struct p2m_domain *p2m,
> > >   struct page_info *pg;
> > > /* Nothing to do if the entry is invalid. */
> > > -if ( !lpae_is_valid(entry) )
> > > +if ( !p2m_is_valid(entry) )
> > >   return;
> > > /* Nothing to do but updating the stats if the entry is a
> > > super-page. */
> > > -if ( p2m_is_superpage(entry, level) )
> > > +if ( level == 3 && entry.p2m.table )
> > 
> > Why?
> 
> Because p2m_is_superpage(...)

Re: [Xen-devel] [RFC 07/16] xen/arm: p2m: Introduce p2m_is_valid and use it

2018-10-30 Thread Julien Grall 

Hi,

On 30/10/2018 00:21, Stefano Stabellini wrote:

On Mon, 8 Oct 2018, Julien Grall wrote:

The LPAE format allows to store information in an entry even with the
valid bit unset. In a follow-up patch, we will take advantage of this
feature to re-purpose the valid bit for generating a translation fault
even if an entry contains valid information.

So we need a different way to know whether an entry contains valid
information. It is possible to use the information hold in the p2m_type
to know for that purpose. Indeed all entries containing valid
information will have a valid p2m type (i.e p2m_type != p2m_invalid).

This patch introduces a new helper p2m_is_valid, which implements that
idea, and replace most of lpae_is_valid call with the new helper. The ones
remaining are for TLBs handling and entries accounting.

With the renaming there are 2 others changes required:
 - Generate table entry with a valid p2m type
 - Detect new mapping for proper stats accounting

Signed-off-by: Julien Grall 
---
  xen/arch/arm/p2m.c | 34 +++---
  1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 6c76298ebc..2a1e7e9be2 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -220,17 +220,26 @@ static p2m_access_t p2m_mem_access_radix_get(struct 
p2m_domain *p2m, gfn_t gfn)
  }
  
  /*

+ * In the case of the P2M, the valid bit is used for other purpose. Use
+ * the type to check whether an entry is valid.
+ */
+static inline bool p2m_is_valid(lpae_t pte)
+{
+return pte.p2m.type != p2m_invalid;
+}
+
+/*
   * lpae_is_* helpers don't check whether the valid bit is set in the
   * PTE. Provide our own overlay to check the valid bit.
   */
  static inline bool p2m_is_mapping(lpae_t pte, unsigned int level)
  {
-return lpae_is_valid(pte) && lpae_is_mapping(pte, level);
+return p2m_is_valid(pte) && lpae_is_mapping(pte, level);
  }
  
  static inline bool p2m_is_superpage(lpae_t pte, unsigned int level)

  {
-return lpae_is_valid(pte) && lpae_is_superpage(pte, level);
+return p2m_is_valid(pte) && lpae_is_superpage(pte, level);
  }
  
  #define GUEST_TABLE_MAP_FAILED 0

@@ -264,7 +273,7 @@ static int p2m_next_level(struct p2m_domain *p2m, bool 
read_only,
  
  entry = *table + offset;
  
-if ( !lpae_is_valid(*entry) )

+if ( !p2m_is_valid(*entry) )
  {
  if ( read_only )
  return GUEST_TABLE_MAP_FAILED;
@@ -356,7 +365,7 @@ mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
  
  entry = table[offsets[level]];
  
-if ( lpae_is_valid(entry) )

+if ( p2m_is_valid(entry) )
  {
  *t = entry.p2m.type;
  
@@ -544,8 +553,11 @@ static lpae_t page_to_p2m_table(struct page_info *page)

  /*
   * The access value does not matter because the hardware will ignore
   * the permission fields for table entry.
+ *
+ * We use p2m_ram_rw so the entry has a valid type. This is important
+ * for p2m_is_valid() to return valid on table entries.
   */
-return mfn_to_p2m_entry(page_to_mfn(page), p2m_invalid, p2m_access_rwx);
+return mfn_to_p2m_entry(page_to_mfn(page), p2m_ram_rw, p2m_access_rwx);
  }
  
  static inline void p2m_write_pte(lpae_t *p, lpae_t pte, bool clean_pte)

@@ -569,7 +581,7 @@ static int p2m_create_table(struct p2m_domain *p2m, lpae_t 
*entry)
  struct page_info *page;
  lpae_t *p;
  
-ASSERT(!lpae_is_valid(*entry));

+ASSERT(!p2m_is_valid(*entry));
  
  page = alloc_domheap_page(NULL, 0);

  if ( page == NULL )
@@ -626,7 +638,7 @@ static int p2m_mem_access_radix_set(struct p2m_domain *p2m, 
gfn_t gfn,
   */
  static void p2m_put_l3_page(const lpae_t pte)
  {
-ASSERT(lpae_is_valid(pte));
+ASSERT(p2m_is_valid(pte));
  
  /*

   * TODO: Handle other p2m types
@@ -654,11 +666,11 @@ static void p2m_free_entry(struct p2m_domain *p2m,
  struct page_info *pg;
  
  /* Nothing to do if the entry is invalid. */

-if ( !lpae_is_valid(entry) )
+if ( !p2m_is_valid(entry) )
  return;
  
  /* Nothing to do but updating the stats if the entry is a super-page. */

-if ( p2m_is_superpage(entry, level) )
+if ( level == 3 && entry.p2m.table )


Why?


Because p2m_is_superpage(...) contains p2m_is_valid(). So we would test twice 
the validity of the p2m.


But I guess this is not a big deal, so I can remove it.





  {
  p2m->stats.mappings[level]--;
  return;
@@ -951,7 +963,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
  else
  p2m->need_flush = true;
  }
-else /* new mapping */
+else if ( !p2m_is_valid(orig_pte) ) /* new mapping */


There are a couple of lpae_is_valid checks just above this line that you
missed, why haven't you changed them?

If you have a good reason, please explain in a comment and/or commit
message.


This is already explained in the commit message:

"This patch

Re: [Xen-devel] [RFC 07/16] xen/arm: p2m: Introduce p2m_is_valid and use it

2018-10-29 Thread Stefano Stabellini 
On Mon, 8 Oct 2018, Julien Grall wrote:
> The LPAE format allows to store information in an entry even with the
> valid bit unset. In a follow-up patch, we will take advantage of this
> feature to re-purpose the valid bit for generating a translation fault
> even if an entry contains valid information.
> 
> So we need a different way to know whether an entry contains valid
> information. It is possible to use the information hold in the p2m_type
> to know for that purpose. Indeed all entries containing valid
> information will have a valid p2m type (i.e p2m_type != p2m_invalid).
> 
> This patch introduces a new helper p2m_is_valid, which implements that
> idea, and replace most of lpae_is_valid call with the new helper. The ones
> remaining are for TLBs handling and entries accounting.
> 
> With the renaming there are 2 others changes required:
> - Generate table entry with a valid p2m type
> - Detect new mapping for proper stats accounting
> 
> Signed-off-by: Julien Grall 
> ---
>  xen/arch/arm/p2m.c | 34 +++---
>  1 file changed, 23 insertions(+), 11 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 6c76298ebc..2a1e7e9be2 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -220,17 +220,26 @@ static p2m_access_t p2m_mem_access_radix_get(struct 
> p2m_domain *p2m, gfn_t gfn)
>  }
>  
>  /*
> + * In the case of the P2M, the valid bit is used for other purpose. Use
> + * the type to check whether an entry is valid.
> + */
> +static inline bool p2m_is_valid(lpae_t pte)
> +{
> +return pte.p2m.type != p2m_invalid;
> +}
> +
> +/*
>   * lpae_is_* helpers don't check whether the valid bit is set in the
>   * PTE. Provide our own overlay to check the valid bit.
>   */
>  static inline bool p2m_is_mapping(lpae_t pte, unsigned int level)
>  {
> -return lpae_is_valid(pte) && lpae_is_mapping(pte, level);
> +return p2m_is_valid(pte) && lpae_is_mapping(pte, level);
>  }
>  
>  static inline bool p2m_is_superpage(lpae_t pte, unsigned int level)
>  {
> -return lpae_is_valid(pte) && lpae_is_superpage(pte, level);
> +return p2m_is_valid(pte) && lpae_is_superpage(pte, level);
>  }
>  
>  #define GUEST_TABLE_MAP_FAILED 0
> @@ -264,7 +273,7 @@ static int p2m_next_level(struct p2m_domain *p2m, bool 
> read_only,
>  
>  entry = *table + offset;
>  
> -if ( !lpae_is_valid(*entry) )
> +if ( !p2m_is_valid(*entry) )
>  {
>  if ( read_only )
>  return GUEST_TABLE_MAP_FAILED;
> @@ -356,7 +365,7 @@ mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
>  
>  entry = table[offsets[level]];
>  
> -if ( lpae_is_valid(entry) )
> +if ( p2m_is_valid(entry) )
>  {
>  *t = entry.p2m.type;
>  
> @@ -544,8 +553,11 @@ static lpae_t page_to_p2m_table(struct page_info *page)
>  /*
>   * The access value does not matter because the hardware will ignore
>   * the permission fields for table entry.
> + *
> + * We use p2m_ram_rw so the entry has a valid type. This is important
> + * for p2m_is_valid() to return valid on table entries.
>   */
> -return mfn_to_p2m_entry(page_to_mfn(page), p2m_invalid, p2m_access_rwx);
> +return mfn_to_p2m_entry(page_to_mfn(page), p2m_ram_rw, p2m_access_rwx);
>  }
>  
>  static inline void p2m_write_pte(lpae_t *p, lpae_t pte, bool clean_pte)
> @@ -569,7 +581,7 @@ static int p2m_create_table(struct p2m_domain *p2m, 
> lpae_t *entry)
>  struct page_info *page;
>  lpae_t *p;
>  
> -ASSERT(!lpae_is_valid(*entry));
> +ASSERT(!p2m_is_valid(*entry));
>  
>  page = alloc_domheap_page(NULL, 0);
>  if ( page == NULL )
> @@ -626,7 +638,7 @@ static int p2m_mem_access_radix_set(struct p2m_domain 
> *p2m, gfn_t gfn,
>   */
>  static void p2m_put_l3_page(const lpae_t pte)
>  {
> -ASSERT(lpae_is_valid(pte));
> +ASSERT(p2m_is_valid(pte));
>  
>  /*
>   * TODO: Handle other p2m types
> @@ -654,11 +666,11 @@ static void p2m_free_entry(struct p2m_domain *p2m,
>  struct page_info *pg;
>  
>  /* Nothing to do if the entry is invalid. */
> -if ( !lpae_is_valid(entry) )
> +if ( !p2m_is_valid(entry) )
>  return;
>  
>  /* Nothing to do but updating the stats if the entry is a super-page. */
> -if ( p2m_is_superpage(entry, level) )
> +if ( level == 3 && entry.p2m.table )

Why?


>  {
>  p2m->stats.mappings[level]--;
>  return;
> @@ -951,7 +963,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
>  else
>  p2m->need_flush = true;
>  }
> -else /* new mapping */
> +else if ( !p2m_is_valid(orig_pte) ) /* new mapping */

There are a couple of lpae_is_valid checks just above this line that you
missed, why haven't you changed them?

If you have a good reason, please explain in a comment and/or commit
message.

>  p2m->stats.mappings[level]++;
>  
>  p2m_write_pte(entry, pte, p2m->clean_pte);
>

[Xen-devel] [RFC 07/16] xen/arm: p2m: Introduce p2m_is_valid and use it

2018-10-08 Thread Julien Grall 
The LPAE format allows to store information in an entry even with the
valid bit unset. In a follow-up patch, we will take advantage of this
feature to re-purpose the valid bit for generating a translation fault
even if an entry contains valid information.

So we need a different way to know whether an entry contains valid
information. It is possible to use the information hold in the p2m_type
to know for that purpose. Indeed all entries containing valid
information will have a valid p2m type (i.e p2m_type != p2m_invalid).

This patch introduces a new helper p2m_is_valid, which implements that
idea, and replace most of lpae_is_valid call with the new helper. The ones
remaining are for TLBs handling and entries accounting.

With the renaming there are 2 others changes required:
- Generate table entry with a valid p2m type
- Detect new mapping for proper stats accounting

Signed-off-by: Julien Grall 
---
 xen/arch/arm/p2m.c | 34 +++---
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 6c76298ebc..2a1e7e9be2 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -220,17 +220,26 @@ static p2m_access_t p2m_mem_access_radix_get(struct 
p2m_domain *p2m, gfn_t gfn)
 }
 
 /*
+ * In the case of the P2M, the valid bit is used for other purpose. Use
+ * the type to check whether an entry is valid.
+ */
+static inline bool p2m_is_valid(lpae_t pte)
+{
+return pte.p2m.type != p2m_invalid;
+}
+
+/*
  * lpae_is_* helpers don't check whether the valid bit is set in the
  * PTE. Provide our own overlay to check the valid bit.
  */
 static inline bool p2m_is_mapping(lpae_t pte, unsigned int level)
 {
-return lpae_is_valid(pte) && lpae_is_mapping(pte, level);
+return p2m_is_valid(pte) && lpae_is_mapping(pte, level);
 }
 
 static inline bool p2m_is_superpage(lpae_t pte, unsigned int level)
 {
-return lpae_is_valid(pte) && lpae_is_superpage(pte, level);
+return p2m_is_valid(pte) && lpae_is_superpage(pte, level);
 }
 
 #define GUEST_TABLE_MAP_FAILED 0
@@ -264,7 +273,7 @@ static int p2m_next_level(struct p2m_domain *p2m, bool 
read_only,
 
 entry = *table + offset;
 
-if ( !lpae_is_valid(*entry) )
+if ( !p2m_is_valid(*entry) )
 {
 if ( read_only )
 return GUEST_TABLE_MAP_FAILED;
@@ -356,7 +365,7 @@ mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
 
 entry = table[offsets[level]];
 
-if ( lpae_is_valid(entry) )
+if ( p2m_is_valid(entry) )
 {
 *t = entry.p2m.type;
 
@@ -544,8 +553,11 @@ static lpae_t page_to_p2m_table(struct page_info *page)
 /*
  * The access value does not matter because the hardware will ignore
  * the permission fields for table entry.
+ *
+ * We use p2m_ram_rw so the entry has a valid type. This is important
+ * for p2m_is_valid() to return valid on table entries.
  */
-return mfn_to_p2m_entry(page_to_mfn(page), p2m_invalid, p2m_access_rwx);
+return mfn_to_p2m_entry(page_to_mfn(page), p2m_ram_rw, p2m_access_rwx);
 }
 
 static inline void p2m_write_pte(lpae_t *p, lpae_t pte, bool clean_pte)
@@ -569,7 +581,7 @@ static int p2m_create_table(struct p2m_domain *p2m, lpae_t 
*entry)
 struct page_info *page;
 lpae_t *p;
 
-ASSERT(!lpae_is_valid(*entry));
+ASSERT(!p2m_is_valid(*entry));
 
 page = alloc_domheap_page(NULL, 0);
 if ( page == NULL )
@@ -626,7 +638,7 @@ static int p2m_mem_access_radix_set(struct p2m_domain *p2m, 
gfn_t gfn,
  */
 static void p2m_put_l3_page(const lpae_t pte)
 {
-ASSERT(lpae_is_valid(pte));
+ASSERT(p2m_is_valid(pte));
 
 /*
  * TODO: Handle other p2m types
@@ -654,11 +666,11 @@ static void p2m_free_entry(struct p2m_domain *p2m,
 struct page_info *pg;
 
 /* Nothing to do if the entry is invalid. */
-if ( !lpae_is_valid(entry) )
+if ( !p2m_is_valid(entry) )
 return;
 
 /* Nothing to do but updating the stats if the entry is a super-page. */
-if ( p2m_is_superpage(entry, level) )
+if ( level == 3 && entry.p2m.table )
 {
 p2m->stats.mappings[level]--;
 return;
@@ -951,7 +963,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
 else
 p2m->need_flush = true;
 }
-else /* new mapping */
+else if ( !p2m_is_valid(orig_pte) ) /* new mapping */
 p2m->stats.mappings[level]++;
 
 p2m_write_pte(entry, pte, p2m->clean_pte);
@@ -965,7 +977,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
  * Free the entry only if the original pte was valid and the base
  * is different (to avoid freeing when permission is changed).
  */
-if ( lpae_is_valid(orig_pte) &&
+if ( p2m_is_valid(orig_pte) &&
  !mfn_eq(lpae_get_mfn(*entry), lpae_get_mfn(orig_pte)) )
 p2m_free_entry(p2m, orig_pte, level);
 
-- 
2.11.0


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