Re: Weekly VMX status report. Xen: #18846 & Xen0: #749

[Keir Fraser <keir.fraser@eu.citrix.com>]

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On 13/12/2008 22:43, "Nakajima, Jun" <jun.nakajima@intel.com> wrote:

>> I think you agree that we don't need to keep guest 'actual' EFER.NX in
>> sync with its 'shadow' EFER.NX?
>> 
> 
> That should be okay. The fact we see the NX bit in the shadow page tables
> means at least the BSP enabled NX. And I don't expect other processors would
> do otherwise. In other words, such out-of-sync situations be transient anyway.

Attached is my proposed patch. Does it look okay to everyone? Haicheng:
could you test if it gets rid of the HVM Solaris crash?

 Thanks,
 Keir


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diff -r f827181eadd4 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c	Mon Dec 15 11:37:14 2008 +0000
+++ b/xen/arch/x86/hvm/vmx/vmx.c	Mon Dec 15 12:59:57 2008 +0000
@@ -306,9 +306,6 @@ static void vmx_restore_host_msrs(void)
         wrmsrl(msr_index[i], host_msr_state->msrs[i]);
         clear_bit(i, &host_msr_state->flags);
     }
-
-    if ( cpu_has_nx && !(read_efer() & EFER_NX) )
-        write_efer(read_efer() | EFER_NX);
 }
 
 static void vmx_save_guest_msrs(struct vcpu *v)
@@ -342,39 +339,23 @@ static void vmx_restore_guest_msrs(struc
         clear_bit(i, &guest_flags);
     }
 
-    if ( (v->arch.hvm_vcpu.guest_efer ^ read_efer()) & (EFER_NX | EFER_SCE) )
+    if ( (v->arch.hvm_vcpu.guest_efer ^ read_efer()) & EFER_SCE )
     {
         HVM_DBG_LOG(DBG_LEVEL_2,
                     "restore guest's EFER with value %lx",
                     v->arch.hvm_vcpu.guest_efer);
-        write_efer((read_efer() & ~(EFER_NX | EFER_SCE)) |
-                   (v->arch.hvm_vcpu.guest_efer & (EFER_NX | EFER_SCE)));
+        write_efer((read_efer() & ~EFER_SCE) |
+                   (v->arch.hvm_vcpu.guest_efer & EFER_SCE));
     }
 }
 
 #else  /* __i386__ */
 
 #define vmx_save_host_msrs()        ((void)0)
-
-static void vmx_restore_host_msrs(void)
-{
-    if ( cpu_has_nx && !(read_efer() & EFER_NX) )
-        write_efer(read_efer() | EFER_NX);
-}
+#define vmx_restore_host_msrs()     ((void)0)
 
 #define vmx_save_guest_msrs(v)      ((void)0)
-
-static void vmx_restore_guest_msrs(struct vcpu *v)
-{
-    if ( (v->arch.hvm_vcpu.guest_efer ^ read_efer()) & EFER_NX )
-    {
-        HVM_DBG_LOG(DBG_LEVEL_2,
-                    "restore guest's EFER with value %lx",
-                    v->arch.hvm_vcpu.guest_efer);
-        write_efer((read_efer() & ~EFER_NX) |
-                   (v->arch.hvm_vcpu.guest_efer & EFER_NX));
-    }
-}
+#define vmx_restore_guest_msrs(v)   ((void)0)
 
 static enum handler_return long_mode_do_msr_read(struct cpu_user_regs *regs)
 {
@@ -1190,8 +1171,8 @@ static void vmx_update_guest_efer(struct
 #endif
 
     if ( v == current )
-        write_efer((read_efer() & ~(EFER_NX|EFER_SCE)) |
-                   (v->arch.hvm_vcpu.guest_efer & (EFER_NX|EFER_SCE)));
+        write_efer((read_efer() & ~EFER_SCE) |
+                   (v->arch.hvm_vcpu.guest_efer & EFER_SCE));
 }
 
 static void vmx_flush_guest_tlbs(void)

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