diff mbox series

[v9,10/13] x86/smpboot: switch clone_mapping() to new APIs

Message ID d55bcecc33df5b277bc3e1dbb48826bc816d8d10.1617706782.git.hongyxia@amazon.com (mailing list archive)
State Superseded
Headers show
Series switch to domheap for Xen page tables | expand

Commit Message

Hongyan Xia April 6, 2021, 11:05 a.m. UTC 
From: Wei Liu <wei.liu2@citrix.com>

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Hongyan Xia <hongyxia@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

---
Changed in v7:
- change patch title
- remove initialiser of pl3e.
- combine the initialisation of pl3e into a single assignment.
- use the new alloc_map_clear() helper.
- use the normal map_domain_page() in the error path.
---
 xen/arch/x86/smpboot.c | 44 ++++++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 17 deletions(-)

Comments

Jan Beulich April 20, 2021, 12:32 p.m. UTC | #1 
On 06.04.2021 13:05, Hongyan Xia wrote:
> @@ -742,51 +742,58 @@ static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
>          }
>      }
>  
> +    UNMAP_DOMAIN_PAGE(pl1e);
> +    UNMAP_DOMAIN_PAGE(pl2e);
> +    UNMAP_DOMAIN_PAGE(pl3e);

Just one minor remark: A pedantic(?) compiler might warn about the
setting to NULL of pl3e here, when

>      if ( !(root_get_flags(rpt[root_table_offset(linear)]) & _PAGE_PRESENT) )
>      {
> -        pl3e = alloc_xen_pagetable();
> +        mfn_t l3mfn;
> +
> +        pl3e = alloc_map_clear_xen_pt(&l3mfn);
>          rc = -ENOMEM;
>          if ( !pl3e )
>              goto out;
> -        clear_page(pl3e);
>          l4e_write(&rpt[root_table_offset(linear)],
> -                  l4e_from_paddr(__pa(pl3e), __PAGE_HYPERVISOR));
> +                  l4e_from_mfn(l3mfn, __PAGE_HYPERVISOR));
>      }
>      else
> -        pl3e = l4e_to_l3e(rpt[root_table_offset(linear)]);
> +        pl3e = map_l3t_from_l4e(rpt[root_table_offset(linear)]);

... it is guaranteed to get initialized again before any further
consumption. IOW strictly speaking the last of those three would
want to be unmap_domain_page(), just like you have ...

> @@ -802,6 +809,9 @@ static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
>  
>      rc = 0;
>   out:
> +    unmap_domain_page(pl1e);
> +    unmap_domain_page(pl2e);
> +    unmap_domain_page(pl3e);
>      return rc;
>  }

... here.

Jan
Hongyan Xia April 21, 2021, 1:39 p.m. UTC | #2 
On Tue, 2021-04-20 at 14:32 +0200, Jan Beulich wrote:
> On 06.04.2021 13:05, Hongyan Xia wrote:
> > @@ -742,51 +742,58 @@ static int clone_mapping(const void *ptr,
> > root_pgentry_t *rpt)
> >          }
> >      }
> >  
> > +    UNMAP_DOMAIN_PAGE(pl1e);
> > +    UNMAP_DOMAIN_PAGE(pl2e);
> > +    UNMAP_DOMAIN_PAGE(pl3e);
> 
> Just one minor remark: A pedantic(?) compiler might warn about the
> setting to NULL of pl3e here, when
> 
> >      if ( !(root_get_flags(rpt[root_table_offset(linear)]) &
> > _PAGE_PRESENT) )
> >      {
> > -        pl3e = alloc_xen_pagetable();
> > +        mfn_t l3mfn;
> > +
> > +        pl3e = alloc_map_clear_xen_pt(&l3mfn);
> >          rc = -ENOMEM;
> >          if ( !pl3e )
> >              goto out;
> > -        clear_page(pl3e);
> >          l4e_write(&rpt[root_table_offset(linear)],
> > -                  l4e_from_paddr(__pa(pl3e), __PAGE_HYPERVISOR));
> > +                  l4e_from_mfn(l3mfn, __PAGE_HYPERVISOR));
> >      }
> >      else
> > -        pl3e = l4e_to_l3e(rpt[root_table_offset(linear)]);
> > +        pl3e = map_l3t_from_l4e(rpt[root_table_offset(linear)]);
> 
> ... it is guaranteed to get initialized again before any further
> consumption. IOW strictly speaking the last of those three would
> want to be unmap_domain_page(), just like you have ...
> 
> > @@ -802,6 +809,9 @@ static int clone_mapping(const void *ptr,
> > root_pgentry_t *rpt)
> >  
> >      rc = 0;
> >   out:
> > +    unmap_domain_page(pl1e);
> > +    unmap_domain_page(pl2e);
> > +    unmap_domain_page(pl3e);
> >      return rc;
> >  }
> 
> ... here.

True. I will switch to lower case for pl3e just in case.

Hongyan
diff mbox series

Patch

diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index e90c4dfa8a88..9c5323977b25 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -694,8 +694,8 @@  static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
     unsigned long linear = (unsigned long)ptr, pfn;
     unsigned int flags;
     l3_pgentry_t *pl3e;
-    l2_pgentry_t *pl2e;
-    l1_pgentry_t *pl1e;
+    l2_pgentry_t *pl2e = NULL;
+    l1_pgentry_t *pl1e = NULL;
     int rc = 0;
 
     /*
@@ -710,7 +710,7 @@  static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
          (linear >= XEN_VIRT_END && linear < DIRECTMAP_VIRT_START) )
         return -EINVAL;
 
-    pl3e = l4e_to_l3e(idle_pg_table[root_table_offset(linear)]) +
+    pl3e = map_l3t_from_l4e(idle_pg_table[root_table_offset(linear)]) +
         l3_table_offset(linear);
 
     flags = l3e_get_flags(*pl3e);
@@ -723,7 +723,7 @@  static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
     }
     else
     {
-        pl2e = l3e_to_l2e(*pl3e) + l2_table_offset(linear);
+        pl2e = map_l2t_from_l3e(*pl3e) + l2_table_offset(linear);
         flags = l2e_get_flags(*pl2e);
         ASSERT(flags & _PAGE_PRESENT);
         if ( flags & _PAGE_PSE )
@@ -734,7 +734,7 @@  static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
         }
         else
         {
-            pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(linear);
+            pl1e = map_l1t_from_l2e(*pl2e) + l1_table_offset(linear);
             flags = l1e_get_flags(*pl1e);
             if ( !(flags & _PAGE_PRESENT) )
                 goto out;
@@ -742,51 +742,58 @@  static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
         }
     }
 
+    UNMAP_DOMAIN_PAGE(pl1e);
+    UNMAP_DOMAIN_PAGE(pl2e);
+    UNMAP_DOMAIN_PAGE(pl3e);
+
     if ( !(root_get_flags(rpt[root_table_offset(linear)]) & _PAGE_PRESENT) )
     {
-        pl3e = alloc_xen_pagetable();
+        mfn_t l3mfn;
+
+        pl3e = alloc_map_clear_xen_pt(&l3mfn);
         rc = -ENOMEM;
         if ( !pl3e )
             goto out;
-        clear_page(pl3e);
         l4e_write(&rpt[root_table_offset(linear)],
-                  l4e_from_paddr(__pa(pl3e), __PAGE_HYPERVISOR));
+                  l4e_from_mfn(l3mfn, __PAGE_HYPERVISOR));
     }
     else
-        pl3e = l4e_to_l3e(rpt[root_table_offset(linear)]);
+        pl3e = map_l3t_from_l4e(rpt[root_table_offset(linear)]);
 
     pl3e += l3_table_offset(linear);
 
     if ( !(l3e_get_flags(*pl3e) & _PAGE_PRESENT) )
     {
-        pl2e = alloc_xen_pagetable();
+        mfn_t l2mfn;
+
+        pl2e = alloc_map_clear_xen_pt(&l2mfn);
         rc = -ENOMEM;
         if ( !pl2e )
             goto out;
-        clear_page(pl2e);
-        l3e_write(pl3e, l3e_from_paddr(__pa(pl2e), __PAGE_HYPERVISOR));
+        l3e_write(pl3e, l3e_from_mfn(l2mfn, __PAGE_HYPERVISOR));
     }
     else
     {
         ASSERT(!(l3e_get_flags(*pl3e) & _PAGE_PSE));
-        pl2e = l3e_to_l2e(*pl3e);
+        pl2e = map_l2t_from_l3e(*pl3e);
     }
 
     pl2e += l2_table_offset(linear);
 
     if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
     {
-        pl1e = alloc_xen_pagetable();
+        mfn_t l1mfn;
+
+        pl1e = alloc_map_clear_xen_pt(&l1mfn);
         rc = -ENOMEM;
         if ( !pl1e )
             goto out;
-        clear_page(pl1e);
-        l2e_write(pl2e, l2e_from_paddr(__pa(pl1e), __PAGE_HYPERVISOR));
+        l2e_write(pl2e, l2e_from_mfn(l1mfn, __PAGE_HYPERVISOR));
     }
     else
     {
         ASSERT(!(l2e_get_flags(*pl2e) & _PAGE_PSE));
-        pl1e = l2e_to_l1e(*pl2e);
+        pl1e = map_l1t_from_l2e(*pl2e);
     }
 
     pl1e += l1_table_offset(linear);
@@ -802,6 +809,9 @@  static int clone_mapping(const void *ptr, root_pgentry_t *rpt)
 
     rc = 0;
  out:
+    unmap_domain_page(pl1e);
+    unmap_domain_page(pl2e);
+    unmap_domain_page(pl3e);
     return rc;
 }