[Xen-changelog] [xen master] x86/PV: don't commit debug register values early in arch_set_info_guest()

[patchbot@xxxxxxx]

commit 398c39b6c18d0b55acfc88f5ee75b3a793e6eeec
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Dec 11 10:33:19 2013 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Dec 11 10:33:19 2013 +0100

    x86/PV: don't commit debug register values early in arch_set_info_guest()
    
    They're being taken care of later (via set_debugreg()), and temporarily
    copying them into struct vcpu means that bad values may end up getting
    loaded during context switch if the vCPU is already running and the
    function errors out between the premature and real commit step, leading
    to the same issue that XSA-12 dealt with.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Release-acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
---
 xen/arch/x86/domain.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index c0ac5d6..da8e522 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -743,11 +743,12 @@ int arch_set_info_guest(
             XLAT_trap_info(v->arch.pv_vcpu.trap_ctxt + i,
                            c.cmp->trap_ctxt + i);
     }
-    for ( i = 0; i < ARRAY_SIZE(v->arch.debugreg); ++i )
-        v->arch.debugreg[i] = c(debugreg[i]);
 
     if ( has_hvm_container_vcpu(v) )
     {
+        for ( i = 0; i < ARRAY_SIZE(v->arch.debugreg); ++i )
+            v->arch.debugreg[i] = c(debugreg[i]);
+
         hvm_set_info_guest(v);
 
         if ( is_hvm_vcpu(v) || v->is_initialised )
--
generated by git-patchbot for /home/xen/git/xen.git#master

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog