From: Jan Beulich <jbeulich@suse.com>
Date: Mon, 5 Nov 2018 10:13:59 +0000 (+0100)
Subject: x86emul: VME and PVI modes require a #GP(0) check first thing
X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~3063
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=efe9cba66c036c452cc2ed7220984aa11be8dcb5;p=xen.git

x86emul: VME and PVI modes require a #GP(0) check first thing

As explicitly spelled out by the SDM, EFLAGS.VIF and EFLAGS.VIP both set
at the start of an instruction trigger #GP(0) independent of actual
instruction.

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

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index e717e6ac14..e69dfdd983 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -3247,6 +3247,11 @@ x86_emulate(
 
     ASSERT(ops->read);
 
+    generate_exception_if((mode_vif() &&
+                           (_regs.eflags & X86_EFLAGS_VIF) &&
+                           (_regs.eflags & X86_EFLAGS_VIP)),
+                          EXC_GP, 0);
+
     rc = x86_decode(&state, ctxt, ops);
     if ( rc != X86EMUL_OKAY )
         return rc;