KVM: selftests: sync_regs test for diag318

The DIAGNOSE 0x0318 instruction, unique to s390x, is a privileged call
that must be intercepted via SIE, handled in userspace, and the
information set by the instruction is communicated back to KVM.

To test the instruction interception, an ad-hoc handler is defined which
simply has a VM execute the instruction and then userspace will extract
the necessary info. The handler is defined such that the instruction
invocation occurs only once. It is up to the caller to determine how the
info returned by this handler should be used.

The diag318 info is communicated from userspace to KVM via a sync_regs
call. This is tested during a sync_regs test, where the diag318 info is
requested via the handler, then the info is stored in the appropriate
register in KVM via a sync registers call.

If KVM does not support diag318, then the tests will print a message
stating that diag318 was skipped, and the asserts will simply test
against a value of 0.

Signed-off-by: Collin Walling <walling@linux.ibm.com>
Link: https://lore.kernel.org/r/20201207154125.10322-1-walling@linux.ibm.com
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/tools/testing/selftests/kvm/s390x/sync_regs_test.c b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
index 5731ccf34917..caf7b8859a94 100644
--- a/tools/testing/selftests/kvm/s390x/sync_regs_test.c
+++ b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
@@ -20,6 +20,7 @@
 
 #include "test_util.h"
 #include "kvm_util.h"
+#include "diag318_test_handler.h"
 
 #define VCPU_ID 5
 
@@ -70,7 +71,7 @@ static void compare_sregs(struct kvm_sregs *left, struct kvm_sync_regs *right)
 
 #undef REG_COMPARE
 
-#define TEST_SYNC_FIELDS   (KVM_SYNC_GPRS|KVM_SYNC_ACRS|KVM_SYNC_CRS)
+#define TEST_SYNC_FIELDS   (KVM_SYNC_GPRS|KVM_SYNC_ACRS|KVM_SYNC_CRS|KVM_SYNC_DIAG318)
 #define INVALID_SYNC_FIELD 0x80000000
 
 int main(int argc, char *argv[])
@@ -152,6 +153,12 @@ int main(int argc, char *argv[])
 
 	run->kvm_valid_regs = TEST_SYNC_FIELDS;
 	run->kvm_dirty_regs = KVM_SYNC_GPRS | KVM_SYNC_ACRS;
+
+	if (get_diag318_info() > 0) {
+		run->s.regs.diag318 = get_diag318_info();
+		run->kvm_dirty_regs |= KVM_SYNC_DIAG318;
+	}
+
 	rv = _vcpu_run(vm, VCPU_ID);
 	TEST_ASSERT(rv == 0, "vcpu_run failed: %d\n", rv);
 	TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
@@ -164,6 +171,9 @@ int main(int argc, char *argv[])
 	TEST_ASSERT(run->s.regs.acrs[0]  == 1 << 11,
 		    "acr0 sync regs value incorrect 0x%x.",
 		    run->s.regs.acrs[0]);
+	TEST_ASSERT(run->s.regs.diag318 == get_diag318_info(),
+		    "diag318 sync regs value incorrect 0x%llx.",
+		    run->s.regs.diag318);
 
 	vcpu_regs_get(vm, VCPU_ID, &regs);
 	compare_regs(&regs, &run->s.regs);
@@ -177,6 +187,7 @@ int main(int argc, char *argv[])
 	run->kvm_valid_regs = TEST_SYNC_FIELDS;
 	run->kvm_dirty_regs = 0;
 	run->s.regs.gprs[11] = 0xDEADBEEF;
+	run->s.regs.diag318 = 0x4B1D;
 	rv = _vcpu_run(vm, VCPU_ID);
 	TEST_ASSERT(rv == 0, "vcpu_run failed: %d\n", rv);
 	TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
@@ -186,6 +197,9 @@ int main(int argc, char *argv[])
 	TEST_ASSERT(run->s.regs.gprs[11] != 0xDEADBEEF,
 		    "r11 sync regs value incorrect 0x%llx.",
 		    run->s.regs.gprs[11]);
+	TEST_ASSERT(run->s.regs.diag318 != 0x4B1D,
+		    "diag318 sync regs value incorrect 0x%llx.",
+		    run->s.regs.diag318);
 
 	kvm_vm_free(vm);