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

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1316273197 -3600
# Node ID cf37d2eec2ef0548588e2e2b2be10798168ce2d1
# Parent  dbfb2e052c4b3e096e4c14c55240ef4fa866e62e
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>
---


diff -r dbfb2e052c4b -r cf37d2eec2ef xen/arch/x86/hvm/vmx/vmcs.c
--- a/xen/arch/x86/hvm/vmx/vmcs.c       Sat Sep 17 16:25:53 2011 +0100
+++ b/xen/arch/x86/hvm/vmx/vmcs.c       Sat Sep 17 16:26:37 2011 +0100
@@ -71,6 +71,7 @@
 static DEFINE_PER_CPU_READ_MOSTLY(struct vmcs_struct *, vmxon_region);
 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;
 
@@ -519,6 +520,7 @@
         printk("CPU%d: unexpected VMXON failure\n", cpu);
         return -EINVAL;
     case 0: /* success */
+        this_cpu(vmxon) = 1;
         break;
     default:
         BUG();
@@ -540,6 +542,9 @@
     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) )
@@ -547,6 +552,7 @@
                                     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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