From: Keir Fraser <keir.fraser@citrix.com>
Date: Tue, 29 Jan 2008 15:27:44 +0000 (+0000)
Subject: x86: Fix HVM hypercall preemption causing guest crash.
X-Git-Tag: 3.1.3-rc3~5
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=1a0dd9293fd3caa661beea80e38340fec3e12edd;p=people%2Fvhanquez%2Fxen.git

x86: Fix HVM hypercall preemption causing guest crash.
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
xen-unstable changeset:   16929:128f7bc0a277375571b4817fc65bfcd14e00a7ec
xen-unstable date:        Tue Jan 29 11:47:42 2008 +0000
---

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index b90079688..b4170cc2b 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1388,7 +1388,12 @@ 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) ?