Ensure segment bases are consistent with their
selectors for VMX guests in VM86 mode.

Signed-off-by: David Lively <dlively@virtualiron.com>

diff -r 880433ba7487 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c	Mon May  1 17:08:02 2006 -0400
+++ b/xen/arch/x86/hvm/vmx/vmx.c	Tue May  2 10:31:03 2006 -0400
@@ -487,6 +487,33 @@ static void vmx_store_cpu_guest_regs(
         __vmptrld(virt_to_maddr(current->arch.hvm_vmx.vmcs));
 }
 
+/* Ensure segment bases are consistent with their
+ * selectors for guests in VM86 mode.
+ */
+static void fixup_vm86_seg_bases(struct cpu_user_regs *regs)
+{
+    unsigned long base;
+
+    BUG_ON(__vmread(GUEST_ES_BASE, &base));
+    if (regs->es << 4 != base)
+        BUG_ON(__vmwrite(GUEST_ES_BASE, regs->es << 4));
+    BUG_ON(__vmread(GUEST_CS_BASE, &base));
+    if (regs->cs << 4 != base)
+        BUG_ON(__vmwrite(GUEST_CS_BASE, regs->cs << 4));
+    BUG_ON(__vmread(GUEST_SS_BASE, &base));
+    if (regs->ss << 4 != base)
+        BUG_ON(__vmwrite(GUEST_SS_BASE, regs->ss << 4));
+    BUG_ON(__vmread(GUEST_DS_BASE, &base));
+    if (regs->ds << 4 != base)
+        BUG_ON(__vmwrite(GUEST_DS_BASE, regs->ds << 4));
+    BUG_ON(__vmread(GUEST_FS_BASE, &base));
+    if (regs->fs << 4 != base)
+        BUG_ON(__vmwrite(GUEST_FS_BASE, regs->fs << 4));
+    BUG_ON(__vmread(GUEST_GS_BASE, &base));
+    if (regs->gs << 4 != base)
+        BUG_ON(__vmwrite(GUEST_GS_BASE, regs->gs << 4));
+}
+
 void vmx_load_cpu_guest_regs(struct vcpu *v, struct cpu_user_regs *regs)
 {
     if ( v != current )
@@ -523,6 +550,8 @@ void vmx_load_cpu_guest_regs(struct vcpu
         __vm_set_bit(EXCEPTION_BITMAP, EXCEPTION_BITMAP_DB);
     else
         __vm_clear_bit(EXCEPTION_BITMAP, EXCEPTION_BITMAP_DB);
+    if (regs->rflags & EF_VM)
+        fixup_vm86_seg_bases(regs);
 
     __vmwrite(GUEST_CS_SELECTOR, regs->cs);
     __vmwrite(GUEST_RIP, regs->rip);
@@ -540,6 +569,8 @@ void vmx_load_cpu_guest_regs(struct vcpu
         __vm_set_bit(EXCEPTION_BITMAP, EXCEPTION_BITMAP_DB);
     else
         __vm_clear_bit(EXCEPTION_BITMAP, EXCEPTION_BITMAP_DB);
+    if (regs->eflags & EF_VM)
+        fixup_vm86_seg_bases(regs);
 
     __vmwrite(GUEST_CS_SELECTOR, regs->cs);
     __vmwrite(GUEST_RIP, regs->eip);