x86: Fix HVM hypercall preemption causing guest crash.

Signed-off-by: Yu Zhao <yu.zhao@intel.com>

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index d7478c178b77529bb6f90f05cd029a95661cb16f..618542f20fb180620227a1f29a3e5d4b6160e9ac 100644 (file)
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1506,7 +1506,12 @@ unsigned long hypercall_create_continuation(
     {
         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) ?