[PATCH AUTOSEL 5.6 102/149] selftests: KVM: s390: fix early guest crash

Sasha Levin
2020-04-11T23:06:01Z

From: Christian Borntraeger <borntraeger@de.ibm.com>

[ Upstream commit 41cbed5b07b5f6ca4ae567059ae7f0ffad1fd454 ]

The guest crashes very early due to changes in the control registers
used by dynamic address translation. Let us use different registers
that will not crash the guest.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/kvm/s390x/resets.c | 27 +++++++++++-----------
1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/s390x/resets.c b/tools/testing/selftests/kvm/s390x/resets.c
index 1485bc6c8999f..cbb343ad5d424 100644
--- a/tools/testing/selftests/kvm/s390x/resets.c
+++ b/tools/testing/selftests/kvm/s390x/resets.c
@@ -23,25 +23,24 @@ struct kvm_run *run;
struct kvm_sync_regs *regs;
static uint64_t regs_null[16];

-static uint64_t crs[16] = { 0x40000ULL,
- 0x42000ULL,
- 0, 0, 0, 0, 0,
- 0x43000ULL,
- 0, 0, 0, 0, 0,
- 0x44000ULL,
- 0, 0
-};
-
static void guest_code_initial(void)
{
- /* Round toward 0 */
- uint32_t fpc = 0x11;
+ /* set several CRs to "safe" value */
+ unsigned long cr2_59 = 0x10; /* enable guarded storage */
+ unsigned long cr8_63 = 0x1; /* monitor mask = 1 */
+ unsigned long cr10 = 1; /* PER START */
+ unsigned long cr11 = -1; /* PER END */
+

/* Dirty registers */
asm volatile (
- " lctlg 0,15,%0\n"
- " sfpc %1\n"
- : : "Q" (crs), "d" (fpc));
+ " lghi 2,0x11\n" /* Round toward 0 */
+ " sfpc 2\n" /* set fpc to !=0 */
+ " lctlg 2,2,%0\n"
+ " lctlg 8,8,%1\n"
+ " lctlg 10,10,%2\n"
+ " lctlg 11,11,%3\n"
+ : : "m" (cr2_59), "m" (cr8_63), "m" (cr10), "m" (cr11) : "2");
GUEST_SYNC(0);
}

--
2.20.1