[Xen-changelog] [xen staging] x86/mem_sharing: enable mem_sharing on first memop

[patchbot@xxxxxxx]

commit 72f8d45d69b84e2f5c76180fe046ecca1b2f99ea
Author:     Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
AuthorDate: Fri Jan 24 10:28:22 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jan 24 10:28:22 2020 +0100

    x86/mem_sharing: enable mem_sharing on first memop
    
    It is wasteful to require separate hypercalls to enable sharing on both the
    parent and the client domain during VM forking. To speed things up we enable
    sharing on the first memop in case it wasn't already enabled.
    
    Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/mm/mem_sharing.c | 52 +++++++++++++++++--------------------------
 1 file changed, 21 insertions(+), 31 deletions(-)

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index da7d142ad8..c39e56f5b9 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1400,6 +1400,24 @@ static int range_share(struct domain *d, struct domain 
*cd,
     return rc;
 }
 
+static inline int mem_sharing_control(struct domain *d, bool enable)
+{
+    if ( enable )
+    {
+        if ( unlikely(!is_hvm_domain(d)) )
+            return -EOPNOTSUPP;
+
+        if ( unlikely(!hap_enabled(d)) )
+            return -ENODEV;
+
+        if ( unlikely(is_iommu_enabled(d)) )
+            return -EXDEV;
+    }
+
+    d->arch.hvm.mem_sharing.enabled = enable;
+    return 0;
+}
+
 int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
 {
     int rc;
@@ -1421,10 +1439,8 @@ int 
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
     if ( rc )
         goto out;
 
-    /* Only HAP is supported */
-    rc = -ENODEV;
-    if ( !mem_sharing_enabled(d) )
-        goto out;
+    if ( !mem_sharing_enabled(d) && (rc = mem_sharing_control(d, true)) )
+        return rc;
 
     switch ( mso.op )
     {
@@ -1432,10 +1448,6 @@ int 
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
     {
         shr_handle_t handle;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = nominate_page(d, _gfn(mso.u.nominate.u.gfn), 0, &handle);
         mso.u.nominate.handle = handle;
     }
@@ -1447,9 +1459,6 @@ int 
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
         gfn_t gfn;
         shr_handle_t handle;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
         rc = mem_sharing_gref_to_gfn(d->grant_table, gref, &gfn, NULL);
         if ( rc < 0 )
             goto out;
@@ -1465,10 +1474,6 @@ int 
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
         struct domain *cd;
         shr_handle_t sh, ch;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = rcu_lock_live_remote_domain_by_id(mso.u.share.client_domain,
                                                &cd);
         if ( rc )
@@ -1535,10 +1540,6 @@ int 
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
         struct domain *cd;
         shr_handle_t sh;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = rcu_lock_live_remote_domain_by_id(mso.u.share.client_domain,
                                                &cd);
         if ( rc )
@@ -1597,9 +1598,6 @@ int 
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
               mso.u.range.opaque > mso.u.range.last_gfn) )
             goto out;
 
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = rcu_lock_live_remote_domain_by_id(mso.u.range.client_domain,
                                                &cd);
         if ( rc )
@@ -1691,18 +1689,10 @@ int mem_sharing_domctl(struct domain *d, struct 
xen_domctl_mem_sharing_op *mec)
 {
     int rc;
 
-    /* Only HAP is supported */
-    if ( !hap_enabled(d) )
-        return -ENODEV;
-
     switch ( mec->op )
     {
     case XEN_DOMCTL_MEM_SHARING_CONTROL:
-        rc = 0;
-        if ( unlikely(is_iommu_enabled(d) && mec->u.enable) )
-            rc = -EXDEV;
-        else
-            d->arch.hvm.mem_sharing_enabled = mec->u.enable;
+        rc = mem_sharing_control(d, mec->u.enable);
         break;
 
     default:
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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