# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1201607262 0
# Node ID 128f7bc0a277375571b4817fc65bfcd14e00a7ec
# Parent  7aa2149a3b0e94eb01b39ae8cf4a41bc225be94e
x86: Fix HVM hypercall preemption causing guest crash.
Signed-off-by: Yu Zhao <yu.zhao@intel.com>

Index: xen-3.2-testing/xen/arch/x86/domain.c
===================================================================
--- xen-3.2-testing.orig/xen/arch/x86/domain.c
+++ xen-3.2-testing/xen/arch/x86/domain.c
@@ -1507,7 +1507,12 @@ unsigned long hypercall_create_continuat
     {
         regs       = guest_cpu_user_regs();
         regs->eax  = op;
-        regs->eip -= 2;  /* re-execute 'syscall' / 'int 0x82' */
+        /*
+         * For PV guest, we update EIP to re-execute 'syscall' / 'int 0x82';
+         * HVM does not need this since 'vmcall' / 'vmmcall' is fault-like.
+         */
+        if ( !is_hvm_vcpu(current) )
+            regs->eip -= 2;  /* re-execute 'syscall' / 'int 0x82' */
 
 #ifdef __x86_64__
         if ( !is_hvm_vcpu(current) ?