[Xen-changelog] [xen-3.2-testing] x86: Fix HVM hypercall preemption causing guest crash.

["Xen patchbot-3.2-testing" <patchbot-3.2-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1201620221 0
# Node ID 8bef057447f05f9bca898c7afa99718df630fbbf
# Parent  ee779ed05081ccda35cebbd80ac5f8d3c5fc27cf
x86: Fix HVM hypercall preemption causing guest crash.
Signed-off-by: Yu Zhao <yu.zhao@xxxxxxxxx>
xen-unstable changeset:   16929:128f7bc0a277375571b4817fc65bfcd14e00a7ec
xen-unstable date:        Tue Jan 29 11:47:42 2008 +0000
---
 xen/arch/x86/domain.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletion(-)

diff -r ee779ed05081 -r 8bef057447f0 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Tue Jan 29 15:23:18 2008 +0000
+++ b/xen/arch/x86/domain.c     Tue Jan 29 15:23:41 2008 +0000
@@ -1506,7 +1506,12 @@ 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) ?

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