[Xen-devel] [PATCH 07/16] 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.

But: maybe this will miss pages in paging-out state?

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

---
 xen/arch/x86/hvm/emulate.c       |    3 ++-
 xen/arch/x86/hvm/hvm.c           |   15 ++++++++++-----
 xen/arch/x86/mm/guest_walk.c     |    3 ++-
 xen/arch/x86/mm/hap/guest_walk.c |    6 ++++--
 4 files changed, 18 insertions(+), 9 deletions(-)

--- xen-unstable.hg-4.1.22344.orig/xen/arch/x86/hvm/emulate.c
+++ xen-unstable.hg-4.1.22344/xen/arch/x86/hvm/emulate.c
@@ -66,7 +66,8 @@ static int hvmemul_do_io(
     ram_mfn = gfn_to_mfn_unshare(p2m, ram_gfn, &p2mt, 0);
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(p2m, ram_gfn);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(p2m, ram_gfn);
         return X86EMUL_RETRY;
     }
     if ( p2m_is_shared(p2mt) )
--- xen-unstable.hg-4.1.22344.orig/xen/arch/x86/hvm/hvm.c
+++ xen-unstable.hg-4.1.22344/xen/arch/x86/hvm/hvm.c
@@ -345,7 +345,8 @@ static int hvm_set_ioreq_page(
         return -EINVAL;
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(p2m, gmfn);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(p2m, gmfn);
         return -ENOENT;
     }
     if ( p2m_is_shared(p2mt) )
@@ -1369,7 +1370,8 @@ static void *__hvm_map_guest_frame(unsig
         return NULL;
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(p2m, gfn);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(p2m, gfn);
         return NULL;
     }
 
@@ -1811,7 +1813,8 @@ static enum hvm_copy_result __hvm_copy(
 
         if ( p2m_is_paging(p2mt) )
         {
-            p2m_mem_paging_populate(p2m, gfn);
+            if ( p2m_is_paged(p2mt) )
+                p2m_mem_paging_populate(p2m, gfn);
             return HVMCOPY_gfn_paged_out;
         }
         if ( p2m_is_shared(p2mt) )
@@ -3118,7 +3121,8 @@ long do_hvm_op(unsigned long op, XEN_GUE
             mfn_t mfn = gfn_to_mfn(p2m, pfn, &t);
             if ( p2m_is_paging(t) )
             {
-                p2m_mem_paging_populate(p2m, pfn);
+                if ( p2m_is_paged(t) )
+                    p2m_mem_paging_populate(p2m, pfn);
 
                 rc = -EINVAL;
                 goto param_fail3;
@@ -3184,7 +3188,8 @@ long do_hvm_op(unsigned long op, XEN_GUE
             mfn = gfn_to_mfn_unshare(p2m, pfn, &t, 0);
             if ( p2m_is_paging(t) )
             {
-                p2m_mem_paging_populate(p2m, pfn);
+                if ( p2m_is_paged(t) )
+                    p2m_mem_paging_populate(p2m, pfn);
 
                 rc = -EINVAL;
                 goto param_fail4;
--- xen-unstable.hg-4.1.22344.orig/xen/arch/x86/mm/guest_walk.c
+++ xen-unstable.hg-4.1.22344/xen/arch/x86/mm/guest_walk.c
@@ -96,7 +96,8 @@ static inline void *map_domain_gfn(struc
     *mfn = gfn_to_mfn_unshare(p2m, gfn_x(gfn), p2mt, 0);
     if ( p2m_is_paging(*p2mt) )
     {
-        p2m_mem_paging_populate(p2m, gfn_x(gfn));
+        if ( p2m_is_paged(*p2mt) )
+            p2m_mem_paging_populate(p2m, gfn_x(gfn));
 
         *rc = _PAGE_PAGED;
         return NULL;
--- xen-unstable.hg-4.1.22344.orig/xen/arch/x86/mm/hap/guest_walk.c
+++ xen-unstable.hg-4.1.22344/xen/arch/x86/mm/hap/guest_walk.c
@@ -50,7 +50,8 @@ unsigned long hap_gva_to_gfn(GUEST_PAGIN
     top_mfn = gfn_to_mfn_unshare(p2m, cr3 >> PAGE_SHIFT, &p2mt, 0);
     if ( p2m_is_paging(p2mt) )
     {
-        p2m_mem_paging_populate(p2m, cr3 >> PAGE_SHIFT);
+        if ( p2m_is_paged(p2mt) )
+            p2m_mem_paging_populate(p2m, cr3 >> PAGE_SHIFT);
 
         pfec[0] = PFEC_page_paged;
         return INVALID_GFN;
@@ -82,7 +83,8 @@ unsigned long hap_gva_to_gfn(GUEST_PAGIN
         gfn_to_mfn_unshare(p2m, gfn_x(gfn), &p2mt, 0);
         if ( p2m_is_paging(p2mt) )
         {
-            p2m_mem_paging_populate(p2m, gfn_x(gfn));
+            if ( p2m_is_paged(p2mt) )
+                p2m_mem_paging_populate(p2m, gfn_x(gfn));
 
             pfec[0] = PFEC_page_paged;
             return INVALID_GFN;


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