[Xen-changelog] [xen-3.1-testing] x86: Fix HVM hypercall preemption causing guest crash.

["Xen patchbot-3.1-testing" <patchbot-3.1-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1201620464 0
# Node ID d03ed9c63d33012d96ecab3a54fcb8e971e47806
# Parent  ef03fdafc731675cbb673c737c522d25f5ef84bf
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 ef03fdafc731 -r d03ed9c63d33 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Mon Jan 28 10:42:14 2008 +0000
+++ b/xen/arch/x86/domain.c     Tue Jan 29 15:27:44 2008 +0000
@@ -1388,7 +1388,12 @@ 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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