[V4 PATCH 3/7] PVH dom0: implement XENMEM_add_to_physmap_range for x86

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

This preparatory patch adds support for XENMEM_add_to_physmap_range
on x86 so it can be used to create a guest on PVH dom0. To this end, 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.

Please note, compat will continue to return -ENOSYS.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
---
 xen/arch/x86/mm.c |   65 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 65 insertions(+), 0 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 6c26026..4ae4523 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4675,6 +4675,39 @@ static int xenmem_add_to_physmap(struct domain *d,
     return xenmem_add_to_physmap_once(d, xatp);
 }
 
+static int xenmem_add_to_physmap_range(struct domain *d,
+                                       struct xen_add_to_physmap_range *xatpr)
+{
+    /* Process entries in reverse order to allow continuations */
+    while ( xatpr->size > 0 )
+    {
+        int rc;
+        xen_ulong_t idx;
+        xen_pfn_t gpfn;
+        struct xen_add_to_physmap xatp;
+
+        if ( copy_from_guest_offset(&idx, xatpr->idxs, xatpr->size-1, 1)  ||
+             copy_from_guest_offset(&gpfn, xatpr->gpfns, xatpr->size-1, 1) )
+            return -EFAULT;
+
+        xatp.space = xatpr->space;
+        xatp.idx = idx;
+        xatp.gpfn = gpfn;
+        rc = xenmem_add_to_physmap_once(d, &xatp);
+
+        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)
 {
     int rc;
@@ -4689,6 +4722,10 @@ 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 for now */
+        if ( xatp.space == XENMAPSPACE_gmfn_foreign )
+            return -EINVAL;
+
         d = rcu_lock_domain_by_any_id(xatp.domid);
         if ( d == NULL )
             return -ESRCH;
@@ -4716,6 +4753,34 @@ 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 ( (rc = xsm_add_to_physmap(XSM_TARGET, current->domain, d)) == 0 )
+            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