[Xen-devel] [PATCH v2 02/19] xen: make two memory hypercalls vNUMA-aware

[Wei Liu <wei.liu2@xxxxxxxxxx>]

Make XENMEM_increase_reservation and XENMEM_populate_physmap
vNUMA-aware.

That is, if guest requests Xen to allocate memory for specific vnode,
Xen can translate vnode to pnode using vNUMA information of that guest.

XENMEMF_vnode is introduced for the guest to mark the node number is in
fact virtual node number and should be translated by Xen.

XENFEAT_memory_op_vnode_supported is introduced to indicate that Xen is
able to translate virtual node to physical node.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
---
Changes in v2:
1. Return start_extent when vnode translation fails.
2. Expose new feature bit to guest.
3. Fix typo in comment.
---
 xen/common/kernel.c           |    1 +
 xen/common/memory.c           |   58 ++++++++++++++++++++++++++++++++++++++---
 xen/include/public/features.h |    3 +++
 xen/include/public/memory.h   |    2 ++
 4 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index d23c422..9f97f68 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -302,6 +302,7 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         {
         case 0:
             fi.submap = 0;
+            fi.submap |= (1U << XENFEAT_memory_op_vnode_supported);
             if ( VM_ASSIST(d, VMASST_TYPE_pae_extended_cr3) )
                 fi.submap |= (1U << XENFEAT_pae_pgdir_above_4gb);
             if ( paging_mode_translate(current->domain) )
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 9f21bd3..f78c403 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -692,6 +692,49 @@ out:
     return rc;
 }
 
+static int translate_vnode_to_pnode(struct domain *d,
+                                    struct xen_memory_reservation *r,
+                                    struct memop_args *a)
+{
+    int rc = 0;
+    unsigned int vnode, pnode;
+
+    /* Note: we don't strictly require non-supported bits set to zero,
+     * so we may have exact_vnode bit set for old guests that don't
+     * support vNUMA.
+     *
+     * To distinguish spurious vnode request v.s. real one, check if
+     * d->vnuma exists.
+     */
+    if ( r->mem_flags & XENMEMF_vnode )
+    {
+        read_lock(&d->vnuma_rwlock);
+        if ( d->vnuma )
+        {
+            vnode = XENMEMF_get_node(r->mem_flags);
+
+            if ( vnode < d->vnuma->nr_vnodes )
+            {
+                pnode = d->vnuma->vnode_to_pnode[vnode];
+
+                a->memflags &=
+                    ~MEMF_node(XENMEMF_get_node(r->mem_flags));
+
+                if ( pnode != NUMA_NO_NODE )
+                {
+                    a->memflags |= MEMF_exact_node;
+                    a->memflags |= MEMF_node(pnode);
+                }
+            }
+            else
+                rc = -EINVAL;
+        }
+        read_unlock(&d->vnuma_rwlock);
+    }
+
+    return rc;
+}
+
 long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
     struct domain *d;
@@ -734,10 +777,6 @@ long do_memory_op(unsigned long cmd, 
XEN_GUEST_HANDLE_PARAM(void) arg)
             args.memflags = MEMF_bits(address_bits);
         }
 
-        args.memflags |= MEMF_node(XENMEMF_get_node(reservation.mem_flags));
-        if ( reservation.mem_flags & XENMEMF_exact_node_request )
-            args.memflags |= MEMF_exact_node;
-
         if ( op == XENMEM_populate_physmap
              && (reservation.mem_flags & XENMEMF_populate_on_demand) )
             args.memflags |= MEMF_populate_on_demand;
@@ -747,6 +786,17 @@ long do_memory_op(unsigned long cmd, 
XEN_GUEST_HANDLE_PARAM(void) arg)
             return start_extent;
         args.domain = d;
 
+        args.memflags |= MEMF_node(XENMEMF_get_node(reservation.mem_flags));
+        if ( reservation.mem_flags & XENMEMF_exact_node_request )
+            args.memflags |= MEMF_exact_node;
+
+        rc = translate_vnode_to_pnode(d, &reservation, &args);
+        if ( rc )
+        {
+            rcu_unlock_domain(d);
+            return start_extent;
+        }
+
         rc = xsm_memory_adjust_reservation(XSM_TARGET, current->domain, d);
         if ( rc )
         {
diff --git a/xen/include/public/features.h b/xen/include/public/features.h
index 16d92aa..2110b04 100644
--- a/xen/include/public/features.h
+++ b/xen/include/public/features.h
@@ -99,6 +99,9 @@
 #define XENFEAT_grant_map_identity        12
  */
 
+/* Guest can use XENMEMF_vnode to specify virtual node for memory op. */
+#define XENFEAT_memory_op_vnode_supported 13
+
 #define XENFEAT_NR_SUBMAPS 1
 
 #endif /* __XEN_PUBLIC_FEATURES_H__ */
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 595f953..2b5206b 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -55,6 +55,8 @@
 /* Flag to request allocation only from the node specified */
 #define XENMEMF_exact_node_request  (1<<17)
 #define XENMEMF_exact_node(n) (XENMEMF_node(n) | XENMEMF_exact_node_request)
+/* Flag to indicate the node specified is virtual node */
+#define XENMEMF_vnode  (1<<18)
 #endif
 
 struct xen_memory_reservation {
-- 
1.7.10.4


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