[Xen-changelog] [xen-4.0-testing] x86/vmx: don't call __vmxoff() blindly

[Xen patchbot-4.0-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1317655569 -3600
# Node ID 3f89d09030e166168f8f472a569c1f3904f3ac00
# Parent  487d9e6505847c195aa38b637a80a4c39523691c
x86/vmx: don't call __vmxoff() blindly

If vmx_vcpu_up() failed, __vmxon() would generally not have got
(successfully) executed, and in that case __vmxoff() will #UD.

Additionally, any panic() during early resume (namely the tboot
related one) would cause vmx_cpu_down() to get executed without
vmx_cpu_up() having run before.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
xen-unstable changeset:   23848:cf37d2eec2ef
xen-unstable date:        Sat Sep 17 16:26:37 2011 +0100
---


diff -r 487d9e650584 -r 3f89d09030e1 xen/arch/x86/hvm/vmx/vmcs.c
--- a/xen/arch/x86/hvm/vmx/vmcs.c       Tue Sep 13 10:42:07 2011 +0100
+++ b/xen/arch/x86/hvm/vmx/vmcs.c       Mon Oct 03 16:26:09 2011 +0100
@@ -70,6 +70,7 @@
 static DEFINE_PER_CPU_READ_MOSTLY(struct vmcs_struct *, host_vmcs);
 static DEFINE_PER_CPU(struct vmcs_struct *, current_vmcs);
 static DEFINE_PER_CPU(struct list_head, active_vmcs_list);
+static DEFINE_PER_CPU(bool_t, vmxon);
 
 static u32 vmcs_revision_id __read_mostly;
 
@@ -442,6 +443,7 @@
         printk("CPU%d: unexpected VMXON failure\n", cpu);
         return 0;
     case 0: /* success */
+        this_cpu(vmxon) = 1;
         break;
     default:
         BUG();
@@ -463,6 +465,9 @@
     struct list_head *active_vmcs_list = &this_cpu(active_vmcs_list);
     unsigned long flags;
 
+    if ( !this_cpu(vmxon) )
+        return;
+
     local_irq_save(flags);
 
     while ( !list_empty(active_vmcs_list) )
@@ -470,6 +475,7 @@
                                     struct vcpu, arch.hvm_vmx.active_list));
 
     BUG_ON(!(read_cr4() & X86_CR4_VMXE));
+    this_cpu(vmxon) = 0;
     __vmxoff();
 
     local_irq_restore(flags);

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