[Xen-devel] [PATCH 09/18] xenpaging: populate only paged-out pages

[Olaf Hering <olaf@xxxxxxxxx>]

populdate a paged-out page only once to reduce pressure in the ringbuffer.
Several cpus may still request a page at once. xenpaging can handle this.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

---
 xen/arch/x86/hvm/emulate.c       |    3 ++-
 xen/arch/x86/hvm/hvm.c           |   17 ++++++++++-------
 xen/arch/x86/mm/guest_walk.c     |    3 ++-
 xen/arch/x86/mm/hap/guest_walk.c |    6 ++++--
 4 files changed, 18 insertions(+), 11 deletions(-)

--- xen-4.0.1-testing.orig/xen/arch/x86/hvm/emulate.c
+++ xen-4.0.1-testing/xen/arch/x86/hvm/emulate.c
@@ -65,7 +65,8 @@ static int hvmemul_do_io(
     ram_mfn = gfn_to_mfn_unshare(current->domain, ram_gfn, &p2mt, 0);
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(curr->domain, ram_gfn);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(curr->domain, ram_gfn);
         return X86EMUL_RETRY;
     }
     if ( p2m_is_shared(p2mt) )
--- xen-4.0.1-testing.orig/xen/arch/x86/hvm/hvm.c
+++ xen-4.0.1-testing/xen/arch/x86/hvm/hvm.c
@@ -291,7 +291,8 @@ static int hvm_set_ioreq_page(
         return -EINVAL;
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(d, gmfn);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(d, gmfn);
         return -ENOENT;
     }
     if ( p2m_is_shared(p2mt) )
@@ -1324,7 +1325,8 @@ static void *hvm_map_entry(unsigned long
     mfn = mfn_x(gfn_to_mfn_unshare(current->domain, gfn, &p2mt, 0));
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(current->domain, gfn);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(current->domain, gfn);
         return NULL;
     }
     if ( p2m_is_shared(p2mt) )
@@ -1723,7 +1725,8 @@ static enum hvm_copy_result __hvm_copy(
 
         if ( p2m_is_paging(p2mt) )
         {
-            p2m_mem_paging_populate(curr->domain, gfn);
+            if ( p2m_is_paged(p2mt) )
+                p2m_mem_paging_populate(curr->domain, gfn);
             return HVMCOPY_gfn_paged_out;
         }
         if ( p2m_is_shared(p2mt) )
@@ -3032,8 +3035,8 @@ long do_hvm_op(unsigned long op, XEN_GUE
             mfn_t mfn = gfn_to_mfn(d, pfn, &t);
             if ( p2m_is_paging(t) )
             {
-                p2m_mem_paging_populate(d, pfn);
-
+                if ( p2m_is_paged(t) )
+                    p2m_mem_paging_populate(d, pfn);
                 rc = -EINVAL;
                 goto param_fail3;
             }
@@ -3096,8 +3099,8 @@ long do_hvm_op(unsigned long op, XEN_GUE
             mfn = gfn_to_mfn_unshare(d, pfn, &t, 0);
             if ( p2m_is_paging(t) )
             {
-                p2m_mem_paging_populate(d, pfn);
-
+                if ( p2m_is_paged(t) )
+                    p2m_mem_paging_populate(d, pfn);
                 rc = -EINVAL;
                 goto param_fail4;
             }
--- xen-4.0.1-testing.orig/xen/arch/x86/mm/guest_walk.c
+++ xen-4.0.1-testing/xen/arch/x86/mm/guest_walk.c
@@ -96,7 +96,8 @@ static inline void *map_domain_gfn(struc
     *mfn = gfn_to_mfn_unshare(d, gfn_x(gfn), p2mt, 0);
     if ( p2m_is_paging(*p2mt) )
     {
-        p2m_mem_paging_populate(d, gfn_x(gfn));
+        if ( p2m_is_paged(*p2mt) )
+            p2m_mem_paging_populate(d, gfn_x(gfn));
 
         *rc = _PAGE_PAGED;
         return NULL;
--- xen-4.0.1-testing.orig/xen/arch/x86/mm/hap/guest_walk.c
+++ xen-4.0.1-testing/xen/arch/x86/mm/hap/guest_walk.c
@@ -49,7 +49,8 @@ unsigned long hap_gva_to_gfn(GUEST_PAGIN
     top_mfn = gfn_to_mfn_unshare(v->domain, cr3 >> PAGE_SHIFT, &p2mt, 0);
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(v->domain, cr3 >> PAGE_SHIFT);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(v->domain, cr3 >> PAGE_SHIFT);
 
         pfec[0] = PFEC_page_paged;
         return INVALID_GFN;
@@ -81,7 +82,8 @@ unsigned long hap_gva_to_gfn(GUEST_PAGIN
         gfn_to_mfn_unshare(v->domain, gfn_x(gfn), &p2mt, 0);
         if ( p2m_is_paging(p2mt) )
         {
-            p2m_mem_paging_populate(v->domain, gfn_x(gfn));
+            if ( p2m_is_paged(p2mt) )
+                p2m_mem_paging_populate(v->domain, gfn_x(gfn));
 
             pfec[0] = PFEC_page_paged;
             return INVALID_GFN;


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