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

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1201607262 0
# Node ID 128f7bc0a277375571b4817fc65bfcd14e00a7ec
# Parent  7aa2149a3b0e94eb01b39ae8cf4a41bc225be94e
x86: Fix HVM hypercall preemption causing guest crash.
Signed-off-by: Yu Zhao <yu.zhao@xxxxxxxxx>
---
 xen/arch/x86/domain.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletion(-)

diff -r 7aa2149a3b0e -r 128f7bc0a277 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Tue Jan 29 11:45:15 2008 +0000
+++ b/xen/arch/x86/domain.c     Tue Jan 29 11:47:42 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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