[for-4.7 v2 0/2] xen: XENMEM_add_to_phymap_batch: Mark 'foreign_id' as reserved for dev_mmio

[for-4.7 v2 0/2] xen: XENMEM_add_to_phymap_batch: Mark 'foreign_id' as reserved for dev_mmio

[Julien Grall]

Hello all,

This series is based on the thread [1]. To allow future extension, the new
space dev_mmio should have all unused fields marked as reserved.

This series is candidate for Xen 4.7, the first patch ensure a clean ABI
for the new space which will allow future extension.

See in each patch for all the changes.

Regards,

[1] http://lists.xenproject.org/archives/html/xen-devel/2016-05/msg02328.html

Julien Grall (2):
  xen: XENMEM_add_to_physmap_batch: Mark 'foreign_id' as reserved for
    dev_mmio
  xen/arm: Document the behavior of XENMAPSPACE_dev_mmio

 xen/arch/arm/mm.c           |  9 +++++++--
 xen/arch/x86/mm.c           |  4 ++--
 xen/common/compat/memory.c  |  2 ++
 xen/common/memory.c         | 12 +++++++++---
 xen/include/public/memory.h | 16 ++++++++++++++--
 xen/include/xen/mm.h        |  3 ++-
 6 files changed, 36 insertions(+), 10 deletions(-)

-- 
1.9.1


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[for-4.7 v2 1/2] xen: XENMEM_add_to_physmap_batch: Mark 'foreign_id' as reserved for dev_mmio

[Julien Grall]

The field 'foreign_id' is not used when the space is dev_mmio. As the
space is not yet part of the stable ABI, the field is marked as reserved
for future use.

The value should always be 0, other values will return -EOPNOTSUPP.

Signed-off-by: Julien Grall <julien.grall@arm.com>

---
    Changes in v2:
        - Return -EOPNOTSUPP rather than -ENOSYS
        - Introduce a union in the sturcutre xenmem_add_to_physmap_batch
---
 xen/arch/arm/mm.c           |  9 +++++++--
 xen/arch/x86/mm.c           |  4 ++--
 xen/common/compat/memory.c  |  2 ++
 xen/common/memory.c         | 12 +++++++++---
 xen/include/public/memory.h | 10 +++++++++-
 xen/include/xen/mm.h        |  3 ++-
 6 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index b46e23e..79f4310 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1047,7 +1047,7 @@ void share_xen_page_with_privileged_guests(
 int xenmem_add_to_physmap_one(
     struct domain *d,
     unsigned int space,
-    domid_t foreign_domid,
+    union add_to_physmap_batch_extra extra,
     unsigned long idx,
     xen_pfn_t gpfn)
 {
@@ -1103,7 +1103,8 @@ int xenmem_add_to_physmap_one(
     {
         struct domain *od;
         p2m_type_t p2mt;
-        od = rcu_lock_domain_by_any_id(foreign_domid);
+
+        od = rcu_lock_domain_by_any_id(extra.foreign_domid);
         if ( od == NULL )
             return -ESRCH;
 
@@ -1143,6 +1144,10 @@ int xenmem_add_to_physmap_one(
         break;
     }
     case XENMAPSPACE_dev_mmio:
+        /* extra should be 0. Reserved for future use. */
+        if ( extra.res0 )
+            return -EOPNOTSUPP;
+
         rc = map_dev_mmio_region(d, gpfn, 1, idx);
         return rc;
 
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 03a4d5b..0b67103 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4769,7 +4769,7 @@ static int handle_iomem_range(unsigned long s, unsigned long e, void *p)
 int xenmem_add_to_physmap_one(
     struct domain *d,
     unsigned int space,
-    domid_t foreign_domid,
+    union add_to_physmap_batch_extra extra,
     unsigned long idx,
     xen_pfn_t gpfn)
 {
@@ -4830,7 +4830,7 @@ int xenmem_add_to_physmap_one(
             break;
         }
         case XENMAPSPACE_gmfn_foreign:
-            return p2m_add_foreign(d, idx, gpfn, foreign_domid);
+            return p2m_add_foreign(d, idx, gpfn, extra.foreign_domid);
         default:
             break;
     }
diff --git a/xen/common/compat/memory.c b/xen/common/compat/memory.c
index 19a914d..e56e187 100644
--- a/xen/common/compat/memory.c
+++ b/xen/common/compat/memory.c
@@ -253,6 +253,8 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat)
             unsigned int size = cmp.atpb.size;
             xen_ulong_t *idxs = (void *)(nat.atpb + 1);
             xen_pfn_t *gpfns = (void *)(idxs + limit);
+            enum XLAT_add_to_physmap_batch_u u =
+                XLAT_add_to_physmap_batch_u_res0;
 
             if ( copy_from_guest(&cmp.atpb, compat, 1) ||
                  !compat_handle_okay(cmp.atpb.idxs, size) ||
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 644f81a..b1ac8b9 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -639,9 +639,15 @@ static int xenmem_add_to_physmap(struct domain *d,
 {
     unsigned int done = 0;
     long rc = 0;
+    union add_to_physmap_batch_extra extra;
+
+    if ( xatp->space != XENMAPSPACE_gmfn_foreign )
+        extra.res0 = 0;
+    else
+        extra.foreign_domid = DOMID_INVALID;
 
     if ( xatp->space != XENMAPSPACE_gmfn_range )
-        return xenmem_add_to_physmap_one(d, xatp->space, DOMID_INVALID,
+        return xenmem_add_to_physmap_one(d, xatp->space, extra,
                                          xatp->idx, xatp->gpfn);
 
     if ( xatp->size < start )
@@ -658,7 +664,7 @@ static int xenmem_add_to_physmap(struct domain *d,
 
     while ( xatp->size > done )
     {
-        rc = xenmem_add_to_physmap_one(d, xatp->space, DOMID_INVALID,
+        rc = xenmem_add_to_physmap_one(d, xatp->space, extra,
                                        xatp->idx, xatp->gpfn);
         if ( rc < 0 )
             break;
@@ -719,7 +725,7 @@ static int xenmem_add_to_physmap_batch(struct domain *d,
         }
 
         rc = xenmem_add_to_physmap_one(d, xatpb->space,
-                                       xatpb->foreign_domid,
+                                       xatpb->u,
                                        idx, gpfn);
 
         if ( unlikely(__copy_to_guest_offset(xatpb->errs, 0, &rc, 1)) )
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index fe52ee1..a5ab139 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -259,7 +259,15 @@ struct xen_add_to_physmap_batch {
 
     /* Number of pages to go through */
     uint16_t size;
-    domid_t foreign_domid; /* IFF gmfn_foreign */
+
+#if __XEN_INTERFACE_VERSION__ < 0x00040700
+    domid_t foreign_domid; /* IFF gmfn_foreign. Should be 0 for other spaces. */
+#else
+    union add_to_physmap_batch_extra {
+        domid_t foreign_domid; /* gmfn_foreign */
+        uint16_t res0;  /* All the other spaces. Should be 0 */
+    } u;
+#endif
 
     /* Indexes into space being mapped. */
     XEN_GUEST_HANDLE(xen_ulong_t) idxs;
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index d4721fc..d82e0a4 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -50,6 +50,7 @@
 #include <xen/list.h>
 #include <xen/spinlock.h>
 #include <xen/typesafe.h>
+#include <public/memory.h>
 
 TYPE_SAFE(unsigned long, mfn);
 #define PRI_mfn          "05lx"
@@ -505,7 +506,7 @@ void scrub_one_page(struct page_info *);
 #endif
 
 int xenmem_add_to_physmap_one(struct domain *d, unsigned int space,
-                              domid_t foreign_domid,
+                              union add_to_physmap_batch_extra extra,
                               unsigned long idx, xen_pfn_t gpfn);
 
 /* Returns 1 on success, 0 on error, negative if the ring
-- 
1.9.1


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Re: [for-4.7 v2 1/2] xen: XENMEM_add_to_physmap_batch: Mark 'foreign_id' as reserved for dev_mmio

[Jan Beulich]

>>> On 25.05.16 at 17:56, <julien.grall@arm.com> wrote:
> --- a/xen/common/compat/memory.c
> +++ b/xen/common/compat/memory.c
> @@ -253,6 +253,8 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat)
>              unsigned int size = cmp.atpb.size;
>              xen_ulong_t *idxs = (void *)(nat.atpb + 1);
>              xen_pfn_t *gpfns = (void *)(idxs + limit);
> +            enum XLAT_add_to_physmap_batch_u u =
> +                XLAT_add_to_physmap_batch_u_res0;

Here you're cheating, and to help future readers understand you are
you should say why this is okay in a comment. Or alternatively handle
things properly.

> --- a/xen/include/public/memory.h
> +++ b/xen/include/public/memory.h
> @@ -259,7 +259,15 @@ struct xen_add_to_physmap_batch {
>  
>      /* Number of pages to go through */
>      uint16_t size;
> -    domid_t foreign_domid; /* IFF gmfn_foreign */
> +
> +#if __XEN_INTERFACE_VERSION__ < 0x00040700
> +    domid_t foreign_domid; /* IFF gmfn_foreign. Should be 0 for other 
> spaces. */
> +#else
> +    union add_to_physmap_batch_extra {

This lacks a xen_ prefix.

Jan


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Re: [for-4.7 v2 1/2] xen: XENMEM_add_to_physmap_batch: Mark 'foreign_id' as reserved for dev_mmio

[Julien Grall]

Hi Jan,

On 27/05/16 10:58, Jan Beulich wrote:
>>>> On 25.05.16 at 17:56, <julien.grall@arm.com> wrote:
>> --- a/xen/common/compat/memory.c
>> +++ b/xen/common/compat/memory.c
>> @@ -253,6 +253,8 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat)
>>               unsigned int size = cmp.atpb.size;
>>               xen_ulong_t *idxs = (void *)(nat.atpb + 1);
>>               xen_pfn_t *gpfns = (void *)(idxs + limit);
>> +            enum XLAT_add_to_physmap_batch_u u =
>> +                XLAT_add_to_physmap_batch_u_res0;
>
> Here you're cheating, and to help future readers understand you are
> you should say why this is okay in a comment. Or alternatively handle
> things properly.

Well, this is the case on other place having to convert union (see 
XENMEM_get_vnumainfo). So I though it was valid.

I will add a comment here.

>
>> --- a/xen/include/public/memory.h
>> +++ b/xen/include/public/memory.h
>> @@ -259,7 +259,15 @@ struct xen_add_to_physmap_batch {
>>
>>       /* Number of pages to go through */
>>       uint16_t size;
>> -    domid_t foreign_domid; /* IFF gmfn_foreign */
>> +
>> +#if __XEN_INTERFACE_VERSION__ < 0x00040700
>> +    domid_t foreign_domid; /* IFF gmfn_foreign. Should be 0 for other
>> spaces. */
>> +#else
>> +    union add_to_physmap_batch_extra {
>
> This lacks a xen_ prefix.

I will fix it.

Regards,

-- 
Julien Grall

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Re: [for-4.7 v2 1/2] xen: XENMEM_add_to_physmap_batch: Mark 'foreign_id' as reserved for dev_mmio

[Jan Beulich]

>>> On 27.05.16 at 17:16, <julien.grall@arm.com> wrote:
> On 27/05/16 10:58, Jan Beulich wrote:
>>>>> On 25.05.16 at 17:56, <julien.grall@arm.com> wrote:
>>> --- a/xen/common/compat/memory.c
>>> +++ b/xen/common/compat/memory.c
>>> @@ -253,6 +253,8 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat)
>>>               unsigned int size = cmp.atpb.size;
>>>               xen_ulong_t *idxs = (void *)(nat.atpb + 1);
>>>               xen_pfn_t *gpfns = (void *)(idxs + limit);
>>> +            enum XLAT_add_to_physmap_batch_u u =
>>> +                XLAT_add_to_physmap_batch_u_res0;
>>
>> Here you're cheating, and to help future readers understand you are
>> you should say why this is okay in a comment. Or alternatively handle
>> things properly.
> 
> Well, this is the case on other place having to convert union (see 
> XENMEM_get_vnumainfo). So I though it was valid.

It depends on context whether you can go this way or need to use
switch().

Jan


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[for-4.7 v2 2/2] xen/arm: Document the behavior of XENMAPSPACE_dev_mmio

[Julien Grall]

Currently, XENMAPSPACE_dev_mmio maps MMIO regions using one of the most
restrictive memory attribute (Device-nGnRE).

Signed-off-by: Julien Grall <julien.grall@arm.com>

---
    Changes in v2:
        - s/Device_nGnRE/Device-nGnRE/ to match the spec
        - Update the comment to mention the name for ARMv7.
---
 xen/include/public/memory.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index a5ab139..cfb427f 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -220,7 +220,11 @@ DEFINE_XEN_GUEST_HANDLE(xen_machphys_mapping_t);
 #define XENMAPSPACE_gmfn_range   3 /* GMFN range, XENMEM_add_to_physmap only. */
 #define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another dom,
                                     * XENMEM_add_to_physmap_batch only. */
-#define XENMAPSPACE_dev_mmio     5 /* device mmio region */
+#define XENMAPSPACE_dev_mmio     5 /* device mmio region
+                                      ARM only; the region will be mapped
+                                      in Stage-2 using the memory attribute
+                                      "Device-nGnRE" (previously named
+                                      "Device" on ARMv7) */
 /* ` } */
 
 /*
-- 
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Re: [for-4.7 v2 2/2] xen/arm: Document the behavior of XENMAPSPACE_dev_mmio

[Jan Beulich]

>>> On 25.05.16 at 17:56, <julien.grall@arm.com> wrote:
> Currently, XENMAPSPACE_dev_mmio maps MMIO regions using one of the most
> restrictive memory attribute (Device-nGnRE).
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>

Acked-by: Jan Beulich <jbeulich@suse.com>
irrespective of whether ...

> --- a/xen/include/public/memory.h
> +++ b/xen/include/public/memory.h
> @@ -220,7 +220,11 @@ DEFINE_XEN_GUEST_HANDLE(xen_machphys_mapping_t);
>  #define XENMAPSPACE_gmfn_range   3 /* GMFN range, XENMEM_add_to_physmap 
> only. */
>  #define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another dom,
>                                      * XENMEM_add_to_physmap_batch only. */
> -#define XENMAPSPACE_dev_mmio     5 /* device mmio region */
> +#define XENMAPSPACE_dev_mmio     5 /* device mmio region
> +                                      ARM only; the region will be mapped
> +                                      in Stage-2 using the memory attribute
> +                                      "Device-nGnRE" (previously named
> +                                      "Device" on ARMv7) */

"will be" would get replaced as suggested by Stefano (I don't think
the current wording is really misleading).

Jan


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