[S390] kvm: fix address mode switching

598841ca9919d008b520114d8a4378c4ce4e40a1 ([S390] use gmap address
spaces for kvm guest images) changed kvm to use a separate address
space for kvm guests. This address space was switched in __vcpu_run
In some cases (preemption, page fault) there is the possibility that
this address space switch is lost.
The typical symptom was a huge amount of validity intercepts or
random guest addressing exceptions.
Fix this by doing the switch in sie_loop and sie_exit and saving the
address space in the gmap structure itself. Also use the preempt
notifier.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 5f729d627cef..713da0760538 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -1076,6 +1076,11 @@ sie_loop:
         lg      %r14,__LC_THREAD_INFO           # pointer thread_info struct
         tm      __TI_flags+7(%r14),_TIF_EXIT_SIE
         jnz     sie_exit
+        lg      %r14,__LC_GMAP                  # get gmap pointer
+        ltgr    %r14,%r14
+        jz      sie_gmap
+        lctlg   %c1,%c1,__GMAP_ASCE(%r14)       # load primary asce
+sie_gmap:
         lg      %r14,__SF_EMPTY(%r15)           # get control block pointer
         SPP     __SF_EMPTY(%r15)                # set guest id
         sie     0(%r14)
@@ -1083,6 +1088,7 @@ sie_done:
         SPP     __LC_CMF_HPP                    # set host id
         lg      %r14,__LC_THREAD_INFO           # pointer thread_info struct
 sie_exit:
+        lctlg   %c1,%c1,__LC_USER_ASCE          # load primary asce
         ni      __TI_flags+6(%r14),255-(_TIF_SIE>>8)
         lg      %r14,__SF_EMPTY+8(%r15)         # load guest register save area
         stmg    %r0,%r13,0(%r14)                # save guest gprs 0-13