[PATCH 02/18] PVH xen: add XENMEM_add_to_physmap_range

[Mukesh Rathor <mukesh.rathor@oracle.com>]

In this patch we add a new function xenmem_add_to_physmap_range(), and
change xenmem_add_to_physmap_once parameters so it can be called from
xenmem_add_to_physmap_range. There is no PVH specific change here.
Note, foreign_domid is useful for XENMAPSPACE_gmfn_foreign only and is
introduced later in the patch series. In this patch, calling with
XENMAPSPACE_gmfn_foreign will result in xenmem_add_to_physmap_once()
returing -EINVAL.

Changes in V2:
  - Do not break parameter so xenmem_add_to_physmap_once() but pass in
    struct xen_add_to_physmap.

Changes in V3:
  - add xsm hook
  - redo xenmem_add_to_physmap_range() a bit as the struct
    xen_add_to_physmap_range got enhanced.

Changes in V6:
  - rcu_lock_target_domain_by_id() got removed, use rcu_lock_domain_by_any_id.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
---
 xen/arch/x86/mm.c |   74 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 71 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 5123860..43f0769 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4519,7 +4519,8 @@ static int handle_iomem_range(unsigned long s, unsigned long e, void *p)
 
 static int xenmem_add_to_physmap_once(
     struct domain *d,
-    const struct xen_add_to_physmap *xatp)
+    const struct xen_add_to_physmap *xatp,
+    domid_t foreign_domid)
 {
     struct page_info *page = NULL;
     unsigned long gfn = 0; /* gcc ... */
@@ -4646,7 +4647,7 @@ static int xenmem_add_to_physmap(struct domain *d,
         start_xatp = *xatp;
         while ( xatp->size > 0 )
         {
-            rc = xenmem_add_to_physmap_once(d, xatp);
+            rc = xenmem_add_to_physmap_once(d, xatp, DOMID_INVALID);
             if ( rc < 0 )
                 return rc;
 
@@ -4672,7 +4673,37 @@ static int xenmem_add_to_physmap(struct domain *d,
         return rc;
     }
 
-    return xenmem_add_to_physmap_once(d, xatp);
+    return xenmem_add_to_physmap_once(d, xatp, DOMID_INVALID);
+}
+
+static int xenmem_add_to_physmap_range(struct domain *d,
+                                       struct xen_add_to_physmap_range *xatpr)
+{
+    int rc;
+
+    /* Process entries in reverse order to allow continuations */
+    while ( xatpr->size > 0 )
+    {
+        struct xen_add_to_physmap xatp;
+
+        if ( copy_from_guest_offset(&xatp.idx, xatpr->idxs, xatpr->size-1, 1)
+             || copy_from_guest_offset(&xatp.gpfn, xatpr->gpfns, xatpr->size-1,
+                                       1) )
+            return -EFAULT;
+
+        xatp.space = xatpr->space;
+        rc = xenmem_add_to_physmap_once(d, &xatp, xatpr->foreign_domid);
+
+        if ( copy_to_guest_offset(xatpr->errs, xatpr->size-1, &rc, 1) )
+            return -EFAULT;
+
+        xatpr->size--;
+
+        /* Check for continuation if it's not the last interation */
+        if ( xatpr->size > 0 && hypercall_preempt_check() )
+            return -EAGAIN;
+    }
+    return 0;
 }
 
 long arch_memory_op(int op, XEN_GUEST_HANDLE_PARAM(void) arg)
@@ -4689,6 +4720,10 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE_PARAM(void) arg)
         if ( copy_from_guest(&xatp, arg, 1) )
             return -EFAULT;
 
+        /* This one is only supported for add_to_physmap_range */
+        if ( xatp.space == XENMAPSPACE_gmfn_foreign )
+            return -EINVAL;
+
         d = rcu_lock_domain_by_any_id(xatp.domid);
         if ( d == NULL )
             return -ESRCH;
@@ -4716,6 +4751,39 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE_PARAM(void) arg)
         return rc;
     }
 
+    case XENMEM_add_to_physmap_range:
+    {
+        struct xen_add_to_physmap_range xatpr;
+        struct domain *d;
+
+        if ( copy_from_guest(&xatpr, arg, 1) )
+            return -EFAULT;
+
+        /* This mapspace is redundant for this hypercall */
+        if ( xatpr.space == XENMAPSPACE_gmfn_range )
+            return -EINVAL;
+
+        d = rcu_lock_domain_by_any_id(xatpr.domid);
+        if ( d == NULL )
+            return -ESRCH;
+
+        if ( xsm_add_to_physmap(XSM_TARGET, current->domain, d) )
+        {
+            rcu_unlock_domain(d);
+            return -EPERM;
+        }
+
+        rc = xenmem_add_to_physmap_range(d, &xatpr);
+
+        rcu_unlock_domain(d);
+
+        if ( rc == -EAGAIN )
+            rc = hypercall_create_continuation(
+                __HYPERVISOR_memory_op, "ih", op, arg);
+
+        return rc;
+    }
+
     case XENMEM_set_memory_map:
     {
         struct xen_foreign_memory_map fmap;
-- 
1.7.2.3