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Re: [Xen-devel] [PATCH]fix xen0 hang when start seconds vmx guest

To: "Ling, Xiaofeng" <xiaofeng.ling@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH]fix xen0 hang when start seconds vmx guest
From: "Ling, Xiaofeng" <xiaofeng.ling@xxxxxxxxx>
Date: Thu, 10 Nov 2005 15:46:27 +0800
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Attach patch can satisfy the audit.
For vmx domain, we also call get_type.

Ling, Xiaofeng wrote:
For vmx domain, because shadow_mode_reference is set later in
vmx_final_setup_guest, so in arch_set_info_guest, the phys_basetab
is not do get_page, while when destroying, put_page is called,
so there is one page, the count=-1, and when a new domain allocate
this page, it will take it as cpumask 0xffffffff, this cause flash_tlb_mask goes into dead loop.(How new bios/microcode can deal with
it? maybe some differnet in sending IPI?)
The warning:
(XEN) Audit 1: type count went below zero mfn=1e03d t=f0000000 ot=3654b
is also caused by this, for vmx domain, the page is net get_type.

I think bug 128, 131, 351 are all caused by this issue.

diff -r 07070a351156 -r 833b086cc0e8 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c Thu Nov 10 12:18:23 2005 +0800
+++ b/xen/arch/x86/domain.c Thu Nov 10 14:05:11 2005 +0800
@@ -389,7 +389,12 @@
         if ( !get_page(&frame_table[phys_basetab>>PAGE_SHIFT], d) )
             return -EINVAL;
     }
-    else if ( !(c->flags & VGCF_VMX_GUEST) )
+    else if ( (c->flags & VGCF_VMX_GUEST) )
+    {
+        if ( !get_page(&frame_table[phys_basetab>>PAGE_SHIFT], d) )
+            return -EINVAL;
+    }
+    else
     {
         if ( !get_page_and_type(&frame_table[phys_basetab>>PAGE_SHIFT], d,
                                 PGT_base_page_table) )


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# HG changeset patch
# User Xiaofeng Ling <xiaofeng.ling@xxxxxxxxx>
# Node ID 833b086cc0e82af98fb5149cebfce08e5e65b4b1
# Parent  07070a3511560287314082abf5f3514d4bfdd0dd
For vmx domain, because shadow_mode_reference is set later in
vmx_final_setup_guest, so in arch_set_info_guest, the phys_basetab
is not do get_page, while when destroying, put_page is called,
so there is one page, the count=-1, and when a new domain allocate
this page, it will take it as cpumask 0xffffffff, this cause flash_tlb_mask
goes into dead loop.
This patch also eliminate the warning when creating vmx guest:
(XEN) Audit 1: type count went below zero mfn=1e03d t=f0000000 ot=3654b

Signed-off-by: Xiaofeng Ling <xiaofeng.ling@xxxxxxxxx>

diff -r 07070a351156 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Thu Nov 10 12:18:23 2005 +0800
+++ b/xen/arch/x86/domain.c     Thu Nov 10 15:36:29 2005 +0800
@@ -389,7 +389,7 @@
         if ( !get_page(&frame_table[phys_basetab>>PAGE_SHIFT], d) )
             return -EINVAL;
     }
-    else if ( !(c->flags & VGCF_VMX_GUEST) )
+    else
     {
         if ( !get_page_and_type(&frame_table[phys_basetab>>PAGE_SHIFT], d,
                                 PGT_base_page_table) )
@@ -962,7 +962,7 @@
     {
         if ( (pfn = pagetable_get_pfn(v->arch.guest_table)) != 0 )
         {
-            if ( !shadow_mode_refcounts(d) )
+            if ( !shadow_mode_refcounts(d) || shadow_mode_external(d) )
                 put_page_type(pfn_to_page(pfn));
             put_page(pfn_to_page(pfn));
 
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