From: Jan Beulich <jbeulich@suse.com>
Date: Mon, 22 Feb 2016 16:23:08 +0000 (+0100)
Subject: x86: drop register reload from INT80 malicious MSI guard
X-Git-Tag: 4.7.0-rc1~527
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=a4b4d3d5a89c61baab042a8972676b6b4f30a9a4;p=xen.git

x86: drop register reload from INT80 malicious MSI guard

None of the restored registers are actually of interest to the
subsequent code (as opposed to the similar construct on the compat
mode hypercall path).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index e0f5c83ac7..dd7f1149d7 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -286,7 +286,6 @@ ENTRY(int80_direct_trap)
 UNLIKELY_START(ne, msi_check)
         movl  $0x80,%edi
         call  check_for_unexpected_msi
-        LOAD_C_CLOBBERED
 UNLIKELY_END(msi_check)
 
         GET_CURRENT(%rbx)