[kvm-unit-tests GIT PULL v2 14/14] s390x: sie: Test whether the epoch extension field is working as expected

Nico Boehr
2023-04-04T11:37:19Z

From: Thomas Huth <thuth@redhat.com>

We recently discovered a bug with the time management in nested scenarios
which got fixed by kernel commit "KVM: s390: vsie: Fix the initialization
of the epoch extension (epdx) field". This adds a simple test for this
bug so that it is easier to determine whether the host kernel of a machine
has already been fixed or not.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20221208170502.17984-1-thuth@redhat.com
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
s390x/sie.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/s390x/sie.c b/s390x/sie.c
index 87575b2..cd3cea1 100644
--- a/s390x/sie.c
+++ b/s390x/sie.c
@@ -58,6 +58,33 @@ static void test_diags(void)
}
}

+static void test_epoch_ext(void)
+{
+ u32 instr[] = {
+ 0xb2780000, /* STCKE 0 */
+ 0x83000044 /* DIAG 0x44 to intercept */
+ };
+
+ if (!test_facility(139)) {
+ report_skip("epdx: Multiple Epoch Facility is not available");
+ return;
+ }
+
+ guest[0] = 0x00;
+ memcpy(guest_instr, instr, sizeof(instr));
+
+ vm.sblk->gpsw.addr = PAGE_SIZE * 2;
+ vm.sblk->gpsw.mask = PSW_MASK_64;
+
+ vm.sblk->ecd |= ECD_MEF;
+ vm.sblk->epdx = 0x47; /* Setting the epoch extension here ... */
+
+ sie(&vm);
+
+ /* ... should result in the same epoch extension here: */
+ report(guest[0] == 0x47, "epdx: different epoch is visible in the guest");
+}
+
static void setup_guest(void)
{
setup_vm();
@@ -80,6 +107,7 @@ int main(void)

setup_guest();
test_diags();
+ test_epoch_ext();
sie_guest_destroy(&vm);

done:
--
2.39.2