[PATCH 4/6] mm: New XENMEM space, XENMAPSPACE_gmfn_range

[Jean Guyader <jean.guyader@eu.citrix.com>]

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XENMAPSPACE_gmfn_range is like XENMAPSPACE_gmfn but it runs on
a range of pages. The size of the range is defined in a new field.

This new field .size is located in the 16 bits padding between .domid
and .space in struct xen_add_to_physmap to stay compatible with older
versions.

Signed-off-by: Jean Guyader <jean.guyader@eu.citrix.com>
---
 xen/arch/x86/mm.c               |   48 ++++++++++++++++++++++++++++++++++++--
 xen/arch/x86/x86_64/compat/mm.c |   14 +++++++++++
 xen/include/public/memory.h     |    4 +++
 3 files changed, 63 insertions(+), 3 deletions(-)


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diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 7cbbb07..126f5b6 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4592,8 +4592,8 @@ static int handle_iomem_range(unsigned long s, unsigned long e, void *p)
     return 0;
 }
 
-static int xenmem_add_to_physmap(struct domain *d,
-                                 struct xen_add_to_physmap xatp)
+static int xenmem_add_to_physmap_once(struct domain *d,
+                                      struct xen_add_to_physmap xatp)
 {
     struct page_info* page = NULL;
     unsigned long mfn = 0;
@@ -4631,6 +4631,7 @@ static int xenmem_add_to_physmap(struct domain *d,
 
         spin_unlock(&d->grant_table->lock);
         break;
+    case XENMAPSPACE_gmfn_range:
     case XENMAPSPACE_gmfn:
     {
         p2m_type_t p2mt;
@@ -4691,6 +4692,37 @@ static int xenmem_add_to_physmap(struct domain *d,
     return rc;
 }
 
+static int xenmem_add_to_physmap(struct domain *d,
+                                 struct xen_add_to_physmap *xatp)
+{
+    int rc = 0;
+
+    if ( xatp->space == XENMAPSPACE_gmfn_range )
+    {
+        while ( xatp->size > 0 )
+        {
+            rc = xenmem_add_to_physmap_once(d, *xatp);
+            if ( rc < 0 )
+                return rc;
+
+            xatp->idx++;
+            xatp->gpfn++;
+            xatp->size--;
+
+            /* Check for continuation if it's not the last interation */
+            if ( xatp->size > 0 && hypercall_preempt_check() )
+            {
+                rc = -EAGAIN;
+                break;
+            }
+        }
+
+        return rc;
+    }
+
+    return xenmem_add_to_physmap_once(d, *xatp);
+}
+
 long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
 {
     int rc;
@@ -4715,10 +4747,20 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
             return -EPERM;
         }
 
-        rc = xenmem_add_to_physmap(d, xatp);
+        rc = xenmem_add_to_physmap(d, &xatp);
 
         rcu_unlock_domain(d);
 
+        if ( rc )
+        {
+            if ( copy_to_guest(arg, &xatp, 1) )
+                return -EFAULT;
+        }
+
+        if ( rc == -EAGAIN )
+            rc = hypercall_create_continuation(
+                    __HYPERVISOR_memory_op, "ih", op, arg);
+
         return rc;
     }
 
diff --git a/xen/arch/x86/x86_64/compat/mm.c b/xen/arch/x86/x86_64/compat/mm.c
index 3ef08a5..2644770 100644
--- a/xen/arch/x86/x86_64/compat/mm.c
+++ b/xen/arch/x86/x86_64/compat/mm.c
@@ -63,6 +63,20 @@ int compat_arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
 
         XLAT_add_to_physmap(nat, &cmp);
         rc = arch_memory_op(op, guest_handle_from_ptr(nat, void));
+        if ( rc )
+        {
+            XLAT_add_to_physmap(&cmp, nat);
+            if ( copy_to_guest(arg, &cmp, 1) )
+            {
+                hypercall_cancel_continuation();
+                return -EFAULT;
+            }
+        }
+        if ( rc < 0 )
+            break;
+
+        if ( rc == __HYPERVISOR_memory_op )
+            hypercall_xlat_continuation(NULL, 0x2, nat, arg);
 
         break;
     }
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 08355e3..c5b78a8 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -208,10 +208,14 @@ struct xen_add_to_physmap {
     /* Which domain to change the mapping for. */
     domid_t domid;
 
+    /* Number of pages to go through for gmfn_range */
+    uint16_t    size;
+
     /* Source mapping space. */
 #define XENMAPSPACE_shared_info 0 /* shared info page */
 #define XENMAPSPACE_grant_table 1 /* grant table page */
 #define XENMAPSPACE_gmfn        2 /* GMFN */
+#define XENMAPSPACE_gmfn_range  3 /* GMFN range */
     unsigned int space;
 
 #define XENMAPIDX_grant_table_status 0x80000000

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