From: Keir Fraser <keir.fraser@citrix.com>
Date: Tue, 29 Jan 2008 11:47:42 +0000 (+0000)
Subject: x86: Fix HVM hypercall preemption causing guest crash.
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14360
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=c8e525b16bc6752f710b649c5a8d5ea706fde747;p=xen.git

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 d7478c178b..618542f20f 100644
--- 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) ?