diff mbox

[4/6] xentrace: ARM platform DOMID_XEN mapping support

Message ID 1458161499-15313-5-git-send-email-ben.sanda@dornerworks.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ben Sanda March 16, 2016, 8:51 p.m. UTC
From: bensanda <ben.sanda@dornerworks.com>

Modified xenmem_add_to_physmap_one() to provide support for xentrace on the ARM platform. Checks for DOMID_XEN added via new function, get_pg_owner, ported from x86 code base. This provides correct calls to rcu_lock_domain() when DOMID_XEN is requested. DOMID_XEN checks also adde to skip page to MFN translation (xentrace sends a MFN dirrectly and so does not need to be translated).

Signed-off-by: Benjamin Sanda <ben.sanda@dornerworks.com>
---
 xen/arch/arm/mm.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 54 insertions(+), 2 deletions(-)

Comments

Julien Grall March 17, 2016, 3:53 p.m. UTC | #1
Hello Benjamin,

Thank you for the patch.

On 16/03/16 20:51, Benjamin Sanda wrote:
> From: bensanda <ben.sanda@dornerworks.com>
>
> Modified xenmem_add_to_physmap_one() to provide support for xentrace on the ARM platform. Checks for DOMID_XEN added via new function, get_pg_owner, ported from x86 code base. This provides correct calls to rcu_lock_domain() when DOMID_XEN is requested. DOMID_XEN checks also adde to skip page to MFN translation (xentrace sends a MFN dirrectly and so does not need to be translated).

A line in the commit message should not be longer than 72 characters.

>
> Signed-off-by: Benjamin Sanda <ben.sanda@dornerworks.com>
> ---
>   xen/arch/arm/mm.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 54 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 81f9e2e..b1d834f 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -41,6 +41,7 @@
>   #include <xen/pfn.h>
>
>   struct domain *dom_xen, *dom_io, *dom_cow;
> +static struct domain *get_pg_owner(domid_t domid);

I would rather avoid to forward declare a function if there is no strict 
dependency on other functions. Instead, I would add the function before 
the caller.

>
>   /* Static start-of-day pagetables that we use before the allocators
>    * are up. These are used by all CPUs during bringup before switching
> @@ -1099,7 +1100,8 @@ int xenmem_add_to_physmap_one(
>       {
>           struct domain *od;
>           p2m_type_t p2mt;
> -        od = rcu_lock_domain_by_any_id(foreign_domid);
> +        od = get_pg_owner(foreign_domid);
> +
>           if ( od == NULL )
>               return -ESRCH;
>
> @@ -1132,7 +1134,17 @@ int xenmem_add_to_physmap_one(
>               return -EINVAL;
>           }
>
> -        mfn = page_to_mfn(page);
> +        /* If DOMID_XEN then no page to MFN translation is
> +        needed as we already have the MFN directly */
> +        if(DOMID_XEN !=od->domain_id)
> +        {
> +            mfn = page_to_mfn(page);
> +        }
> +        else
> +        {
> +            mfn = idx;
> +        }
> +

Please avoid to spread the DOMID_ID specific case everywhere. The cost 
to calculate the MFN of a page is very limited.

>           t = p2m_map_foreign;
>
>           rcu_unlock_domain(od);
> @@ -1312,6 +1324,46 @@ void clear_and_clean_page(struct page_info *page)
>       unmap_domain_page(p);
>   }
>
> +/* Ported from x86 architecture: checks for special domain requests for
> +DOMID_XEN or DOMID_IO which must be handled differently then guest domain
> +requests */
> +static struct domain *get_pg_owner(domid_t domid)

This function is very similar to the x86 one. I think it would benefit 
to implement get_pg_owner in the common code and add arch specific 
helper when it's necessary.

Also, please introduce the helper put_pg_owner to stay consistent.

> +{
> +    struct domain *pg_owner = NULL, *curr = current->domain;
> +
> +    if ( likely(domid == DOMID_SELF) )
> +    {
> +        pg_owner = rcu_lock_current_domain();
> +        goto out;
> +    }
> +
> +    if ( unlikely(domid == curr->domain_id) )
> +    {
> +        goto out;
> +    }
> +
> +    /* check for special domain cases of DOMID_IO or DOMID_XEN which
> +    must use rcu_lock_domain() and dom_xen/dom_io as the domid_t */
> +    switch ( domid )
> +    {
> +    case DOMID_IO:
> +        pg_owner = rcu_lock_domain(dom_io);
> +        break;
> +    case DOMID_XEN:
> +        pg_owner = rcu_lock_domain(dom_xen);
> +        break;
> +    default:
> +        if ( (pg_owner = rcu_lock_domain_by_id(domid)) == NULL )
> +        {
> +            break;
> +        }
> +        break;
> +    }
> +
> + out:
> +    return pg_owner;
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
>

Regards,
diff mbox

Patch

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 81f9e2e..b1d834f 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -41,6 +41,7 @@ 
 #include <xen/pfn.h>
 
 struct domain *dom_xen, *dom_io, *dom_cow;
+static struct domain *get_pg_owner(domid_t domid);
 
 /* Static start-of-day pagetables that we use before the allocators
  * are up. These are used by all CPUs during bringup before switching
@@ -1099,7 +1100,8 @@  int xenmem_add_to_physmap_one(
     {
         struct domain *od;
         p2m_type_t p2mt;
-        od = rcu_lock_domain_by_any_id(foreign_domid);
+        od = get_pg_owner(foreign_domid);
+
         if ( od == NULL )
             return -ESRCH;
 
@@ -1132,7 +1134,17 @@  int xenmem_add_to_physmap_one(
             return -EINVAL;
         }
 
-        mfn = page_to_mfn(page);
+        /* If DOMID_XEN then no page to MFN translation is 
+        needed as we already have the MFN directly */
+        if(DOMID_XEN !=od->domain_id)
+        {
+            mfn = page_to_mfn(page);
+        }
+        else
+        {
+            mfn = idx;
+        }
+
         t = p2m_map_foreign;
 
         rcu_unlock_domain(od);
@@ -1312,6 +1324,46 @@  void clear_and_clean_page(struct page_info *page)
     unmap_domain_page(p);
 }
 
+/* Ported from x86 architecture: checks for special domain requests for
+DOMID_XEN or DOMID_IO which must be handled differently then guest domain 
+requests */
+static struct domain *get_pg_owner(domid_t domid)
+{
+    struct domain *pg_owner = NULL, *curr = current->domain;
+
+    if ( likely(domid == DOMID_SELF) )
+    {
+        pg_owner = rcu_lock_current_domain();
+        goto out;
+    }
+
+    if ( unlikely(domid == curr->domain_id) )
+    {
+        goto out;
+    }
+
+    /* check for special domain cases of DOMID_IO or DOMID_XEN which
+    must use rcu_lock_domain() and dom_xen/dom_io as the domid_t */
+    switch ( domid )
+    {
+    case DOMID_IO:
+        pg_owner = rcu_lock_domain(dom_io);
+        break;
+    case DOMID_XEN:
+        pg_owner = rcu_lock_domain(dom_xen);
+        break;
+    default:
+        if ( (pg_owner = rcu_lock_domain_by_id(domid)) == NULL )
+        {
+            break;
+        }
+        break;
+    }
+
+ out:
+    return pg_owner;
+}
+
 /*
  * Local variables:
  * mode: C