[Xen-changelog] [xen-unstable] [XEN] Fix shadow linear-mapping recopy code for SMP PAE HVM on 64bit Xen.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User tdeegan@xxxxxxxxxxxxxxxxxxxxx
# Node ID 2017f6e92bf8e8a902a1b86e1808b5cf54eeeb50
# Parent  1c3455182cee5db602c59afbe6b6eaa47aa41c9f
[XEN] Fix shadow linear-mapping recopy code for SMP PAE HVM on 64bit Xen.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
---
 xen/arch/x86/mm/shadow/multi.c |   66 ++++++++---------------------------------
 1 files changed, 14 insertions(+), 52 deletions(-)

diff -r 1c3455182cee -r 2017f6e92bf8 xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c    Thu Aug 31 12:07:46 2006 +0100
+++ b/xen/arch/x86/mm/shadow/multi.c    Thu Aug 31 14:46:28 2006 +0100
@@ -2861,11 +2861,11 @@ static int sh_page_fault(struct vcpu *v,
     //      bunch of 4K maps.
     //
 
+    shadow_lock(d);
+
     SHADOW_PRINTK("d:v=%u:%u va=%#lx err=%u\n",
                    v->domain->domain_id, v->vcpu_id, va, regs->error_code);
     
-    shadow_lock(d);
-
     shadow_audit_tables(v);
                    
     if ( guest_walk_tables(v, va, &gw, 1) != 0 )
@@ -3291,12 +3291,6 @@ sh_update_linear_entries(struct vcpu *v)
         {
             ml3e = __linear_l3_table;
             l3mfn = _mfn(l4e_get_pfn(__linear_l4_table[0]));
-#if GUEST_PAGING_LEVELS == 2
-            /* Shadow l3 tables are made up by update_cr3 */
-            sl3e = v->arch.hvm_vcpu.hvm_lowmem_l3tab;
-#else
-            sl3e = v->arch.shadow_vtable;
-#endif
         }
         else 
         {   
@@ -3306,13 +3300,15 @@ sh_update_linear_entries(struct vcpu *v)
             l3mfn = _mfn(l4e_get_pfn(ml4e[0]));
             ml3e = sh_map_domain_page(l3mfn);
             sh_unmap_domain_page(ml4e);
+        }
+
 #if GUEST_PAGING_LEVELS == 2
-            /* Shadow l3 tables are made up by update_cr3 */
-            sl3e = v->arch.hvm_vcpu.hvm_lowmem_l3tab;
+        /* Shadow l3 tables are made up by update_cr3 */
+        sl3e = v->arch.hvm_vcpu.hvm_lowmem_l3tab;
 #else
-            sl3e = sh_map_domain_page(pagetable_get_mfn(v->arch.shadow_table));
-#endif
-        }
+        /* Always safe to use shadow_vtable, because it's globally mapped */
+        sl3e = v->arch.shadow_vtable;
+#endif
 
         for ( i = 0; i < SHADOW_L3_PAGETABLE_ENTRIES; i++ )
         {
@@ -3324,12 +3320,7 @@ sh_update_linear_entries(struct vcpu *v)
         }
 
         if ( v != current ) 
-        {
             sh_unmap_domain_page(ml3e);
-#if GUEST_PAGING_LEVELS != 2
-            sh_unmap_domain_page(sl3e);
-#endif
-        }
     }
 
 #elif CONFIG_PAGING_LEVELS == 3
@@ -3361,31 +3352,10 @@ sh_update_linear_entries(struct vcpu *v)
         
 #else /* GUEST_PAGING_LEVELS == 3 */
         
-        /* Use local vcpu's mappings if we can; otherwise make new mappings */
-        if ( v == current ) 
-        {
-            shadow_l3e = v->arch.shadow_vtable;
-            if ( !shadow_mode_external(d) )
-                guest_l3e = v->arch.guest_vtable;
-        }
-        else 
-        {
-            mfn_t smfn;
-            int idx;
-            
-            /* Map the shadow l3 */
-            smfn = pagetable_get_mfn(v->arch.shadow_table);
-            idx = shadow_l3_index(&smfn, guest_index(v->arch.shadow_vtable));
-            shadow_l3e = sh_map_domain_page(smfn);
-            shadow_l3e += idx;
-            if ( !shadow_mode_external(d) )
-            {
-                /* Also the guest l3 */
-                mfn_t gmfn = pagetable_get_mfn(v->arch.guest_table); 
-                guest_l3e = sh_map_domain_page(gmfn);
-                guest_l3e += guest_index(v->arch.guest_vtable);
-            }
-        }
+        /* Always safe to use *_vtable, because they're globally mapped */
+        shadow_l3e = v->arch.shadow_vtable;
+        guest_l3e = v->arch.guest_vtable;
+
 #endif /* GUEST_PAGING_LEVELS */
         
         /* Choose where to write the entries, using linear maps if possible */
@@ -3443,14 +3413,6 @@ sh_update_linear_entries(struct vcpu *v)
         if ( v != current || !shadow_mode_external(d) )
             sh_unmap_domain_page(l2e);
         
-#if GUEST_PAGING_LEVELS == 3
-        if ( v != current) 
-        {
-            sh_unmap_domain_page(shadow_l3e);
-            if ( !shadow_mode_external(d) )
-                sh_unmap_domain_page(guest_l3e);
-        }
-#endif
     }
 
 #elif CONFIG_PAGING_LEVELS == 2
@@ -3601,7 +3563,7 @@ sh_detach_old_tables(struct vcpu *v)
          v->arch.shadow_vtable )
     {
         // Q: why does this need to use (un)map_domain_page_*global* ?
-        //
+        /* A: so sh_update_linear_entries can operate on other vcpus */
         sh_unmap_domain_page_global(v->arch.shadow_vtable);
         v->arch.shadow_vtable = NULL;
     }

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