[Xen-changelog] [xen-unstable] Fix PV CPUID virtualization of XSave

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Shan Haitao <haitao.shan@xxxxxxxxx>
# Date 1316300518 -3600
# Node ID b78235de5c6407023759f9bbf723dd83887fedf0
# Parent  c944e82bb092925f31403a129087e9d40e0fa06a
Fix PV CPUID virtualization of XSave

The patch will fix XSave CPUID virtualization for PV guests. The XSave
area size returned by CPUID leaf D is changed dynamically depending on
the XCR0. Tools/libxc only assigns a static value. The fix will adjust
xsave area size during runtime.

Note: This fix is already in HVM cpuid virtualization. And Dom0 is not
affected, either.

Signed-off-by:  Shan Haitao <haitao.shan@xxxxxxxxx>
---


diff -r c944e82bb092 -r b78235de5c64 xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c    Sun Sep 18 00:00:26 2011 +0100
+++ b/xen/arch/x86/hvm/hvm.c    Sun Sep 18 00:01:58 2011 +0100
@@ -2426,7 +2426,7 @@
         {
             /* reset EBX to default value first */
             *ebx = XSTATE_AREA_MIN_SIZE; 
-            for ( sub_leaf = 2; sub_leaf < 64; sub_leaf++ )
+            for ( sub_leaf = 2; sub_leaf < 63; sub_leaf++ )
             {
                 if ( !(v->arch.xcr0 & (1ULL << sub_leaf)) )
                     continue;
diff -r c944e82bb092 -r b78235de5c64 xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c      Sun Sep 18 00:00:26 2011 +0100
+++ b/xen/arch/x86/traps.c      Sun Sep 18 00:01:58 2011 +0100
@@ -770,6 +770,30 @@
     {
         if ( !cpuid_hypervisor_leaves(a, c, &a, &b, &c, &d) )
             domain_cpuid(current->domain, a, c, &a, &b, &c, &d);
+
+        switch ( a )
+        {
+        case 0xd:
+        {
+            unsigned int sub_leaf, _eax, _ebx, _ecx, _edx;
+            /* EBX value of main leaf 0 depends on enabled xsave features */
+            if ( c == 0 && current->arch.xcr0 )
+            {
+                /* reset EBX to default value first */
+                b = XSTATE_AREA_MIN_SIZE;
+                for ( sub_leaf = 2; sub_leaf < 63; sub_leaf++ )
+                {
+                    if ( !(current->arch.xcr0 & (1ULL << sub_leaf)) )
+                        continue;
+                    domain_cpuid(current->domain, a, c, &_eax, &_ebx, &_ecx,
+                                 &_edx);
+                    if ( (_eax + _ebx) > b )
+                        b = _eax + _ebx;
+                }
+            }
+        break;
+        }
+        }
         goto out;
     }
 

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