[Xen-changelog] Remove unnecessary cr4 handling in vmx_set_cr0.

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

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 96ba0a2bc9de7da1c70a2528481f7448f3a9524d
# Parent  9af36c14ae8326130cdb2ba5d64e927b09bb6871
Remove unnecessary cr4 handling in vmx_set_cr0.
1) on x86_32, PAE should never be enabled in guest cr4, since we only
support pure IA32 VMX guest.
2) on x86_32p or x86_64, PAE should always be enabled in guest cr4,
since even pure IA32 guest uses PAE paging mode actually.

Signed-off-by: Xin Li <xin.b.li@xxxxxxxxx>
Signed-off-by: Yunhong Jiang <yunhong.jiang@xxxxxxxxx>

diff -r 9af36c14ae83 -r 96ba0a2bc9de xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Wed Mar 15 12:24:59 2006
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Wed Mar 15 12:35:43 2006
@@ -1219,8 +1219,6 @@
 
     if ( (value & X86_CR0_PE) && (value & X86_CR0_PG) && !paging_enabled )
     {
-        unsigned long cr4;
-
         /*
          * Trying to enable guest paging.
          * The guest CR3 must be pointing to the guest physical.
@@ -1269,16 +1267,6 @@
                 domain_crash_synchronous(); /* need to take a clean path */
             }
 #endif
-        }
-
-        /* update CR4's PAE if needed */
-        __vmread(GUEST_CR4, &cr4);
-        if ( (!(cr4 & X86_CR4_PAE)) &&
-             test_bit(VMX_CPU_STATE_PAE_ENABLED,
-                      &v->arch.hvm_vmx.cpu_state) )
-        {
-            HVM_DBG_LOG(DBG_LEVEL_1, "enable PAE in cr4\n");
-            __vmwrite(GUEST_CR4, cr4 | X86_CR4_PAE);
         }
 
         /*

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