[kvm-unit-tests PATCH v2 1/3] s390x: Fix initial cr0 load comments

Janosch Frank
2019-11-11T15:35:11Z

We need to load cr0 to have access to all fprs during save and restore
of fprs. Saving conditionally on basis of the CR0 AFP bit would be a
pain.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
s390x/cstart64.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index 8e2b21e..043e34a 100644
--- a/s390x/cstart64.S
+++ b/s390x/cstart64.S
@@ -94,7 +94,7 @@ memsetxc:
stmg %r0, %r15, GEN_LC_SW_INT_GRS
/* save cr0 */
stctg %c0, %c0, GEN_LC_SW_INT_CR0
- /* load initial cr0 again */
+ /* load a cr0 that has the AFP control bit which enables all FPRs */
larl %r1, initial_cr0
lctlg %c0, %c0, 0(%r1)
/* save fprs 0-15 + fpc */
@@ -139,7 +139,7 @@ diag308_load_reset:
xgr %r2, %r2
br %r14
/* Success path */
- /* We lost cr0 due to the reset */
+ /* load a cr0 that has the AFP control bit which enables all FPRs */
0: larl %r1, initial_cr0
lctlg %c0, %c0, 0(%r1)
RESTORE_REGS
--
2.20.1