[kvm-unit-tests PATCH v2 1/1] s390x: cmm: test no-translate bit after reset

[Nico Boehr <nrb@linux.ibm.com>]

KVM did not properly reset the no-translate bit after reset, see
https://lore.kernel.org/kvm/20231109123624.37314-1-imbrenda@linux.ibm.com/

Add a test which performs a load normal reset (includes a subsystem
reset) and verify that this clears the no-translate bit.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 s390x/cmm.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/s390x/cmm.c b/s390x/cmm.c
index af852838851e..ca6eb00bd663 100644
--- a/s390x/cmm.c
+++ b/s390x/cmm.c
@@ -9,6 +9,7 @@
  */
 
 #include <libcflat.h>
+#include <bitops.h>
 #include <asm/asm-offsets.h>
 #include <asm/interrupt.h>
 #include <asm/page.h>
@@ -16,6 +17,8 @@
 
 static uint8_t pagebuf[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
 
+extern int diag308_load_reset(u64);
+
 static void test_params(void)
 {
 	report_prefix_push("invalid ORC 8");
@@ -35,6 +38,26 @@ static void test_priv(void)
 	report_prefix_pop();
 }
 
+static void test_reset_no_translate(void)
+{
+	const uint64_t mask_no_translate = BIT(63 - 58);
+	unsigned long state;
+
+	report_prefix_push("reset no-translate");
+	essa(ESSA_SET_STABLE_NODAT, (unsigned long)pagebuf);
+
+	state = essa(ESSA_GET_STATE, (unsigned long)pagebuf);
+	report(state & mask_no_translate, "no-translate bit set before reset");
+
+	/* Load normal reset - includes subsystem reset */
+	diag308_load_reset(1);
+
+	state = essa(ESSA_GET_STATE, (unsigned long)pagebuf);
+	report(!(state & mask_no_translate), "no-translate bit unset after reset");
+
+	report_prefix_pop();
+}
+
 int main(void)
 {
 	bool has_essa = check_essa_available();
@@ -47,6 +70,7 @@ int main(void)
 
 	test_priv();
 	test_params();
+	test_reset_no_translate();
 done:
 	report_prefix_pop();
 	return report_summary();
-- 
2.41.0