mm: New XENMEM space, XENMAPSPACE_gmfn_range

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>
Committed-by: Keir Fraser <keir@xen.org>

xen/arch/x86/mm.c

@@ -4677,8 +4677,8 @@ static int handle_iomem_range(unsigned long s, unsigned long e, void *p)
     return 0;
 }
 
-static int xenmem_add_to_physmap(struct domain *d,
-                                 const struct xen_add_to_physmap *xatp)
+static int xenmem_add_to_physmap_once(struct domain *d,
+                                      const struct xen_add_to_physmap *xatp)
 {
     struct page_info *page = NULL;
     unsigned long gfn = 0; /* gcc ... */
@@ -4717,6 +4717,7 @@ 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;
@@ -4744,7 +4745,8 @@ static int xenmem_add_to_physmap(struct domain *d,
     {
         if ( page )
             put_page(page);
-        if ( xatp->space == XENMAPSPACE_gmfn )
+        if ( xatp->space == XENMAPSPACE_gmfn ||
+             xatp->space == XENMAPSPACE_gmfn_range )
             put_gfn(d, gfn);
         rcu_unlock_domain(d);
         return -EINVAL;
@@ -4779,7 +4781,8 @@ static int xenmem_add_to_physmap(struct domain *d,
     rc = guest_physmap_add_page(d, xatp->gpfn, mfn, PAGE_ORDER_4K);
 
     /* In the XENMAPSPACE_gmfn, we took a ref and locked the p2m at the top */
-    if ( xatp->space == XENMAPSPACE_gmfn )
+    if ( xatp->space == XENMAPSPACE_gmfn ||
+         xatp->space == XENMAPSPACE_gmfn_range )
         put_gfn(d, gfn);
     domain_unlock(d);
 
@@ -4788,6 +4791,37 @@ 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;
@@ -4816,6 +4850,19 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
 
         rcu_unlock_domain(d);
 
+        if ( xatp.space == XENMAPSPACE_gmfn_range )
+        {
+            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;
     }
 

xen/arch/x86/x86_64/compat/mm.c

@@ -64,6 +64,21 @@ 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 ( cmp.space == XENMAPSPACE_gmfn_range )
+        {
+            if ( rc )
+            {
+                XLAT_add_to_physmap(&cmp, nat);
+                if ( copy_to_guest(arg, &cmp, 1) )
+                {
+                    hypercall_cancel_continuation();
+                    return -EFAULT;
+                }
+            }
+            if ( rc == __HYPERVISOR_memory_op )
+                hypercall_xlat_continuation(NULL, 0x2, nat, arg);
+        }
+
         break;
     }
 

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