[PATCH kvm-unit-tests v1 2/8] s390x: Add test for PFMF low-address protection

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

PFMF should respect the low-address protection when clearing pages, hence
add some tests for it.

When low-address protection fails, clearing frame 0 is a destructive
operation. It messes up interrupts and thus printing test results won't
work properly. Hence, we first attempt to clear frame 1 which is not as
destructive.

Doing it this way around increases the chances for the user to see a
proper failure message instead of QEMU randomly quitting in the middle
of the test run.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
---
 s390x/pfmf.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/s390x/pfmf.c b/s390x/pfmf.c
index 2f3cb110dc4c..aa1305292ee8 100644
--- a/s390x/pfmf.c
+++ b/s390x/pfmf.c
@@ -113,6 +113,34 @@ static void test_1m_clear(void)
 	report_prefix_pop();
 }
 
+static void test_low_addr_prot(void)
+{
+	union pfmf_r1 r1 = {
+		.reg.cf = 1,
+		.reg.fsc = PFMF_FSC_4K
+	};
+
+	report_prefix_push("low-address protection");
+
+	report_prefix_push("0x1000");
+	expect_pgm_int();
+	low_prot_enable();
+	pfmf(r1.val, (void *)0x1000);
+	low_prot_disable();
+	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
+	report_prefix_pop();
+
+	report_prefix_push("0x0");
+	expect_pgm_int();
+	low_prot_enable();
+	pfmf(r1.val, 0);
+	low_prot_disable();
+	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
+	report_prefix_pop();
+
+	report_prefix_pop();
+}
+
 int main(void)
 {
 	bool has_edat = test_facility(8);
@@ -124,6 +152,7 @@ int main(void)
 	}
 
 	test_priv();
+	test_low_addr_prot();
 	/* Force the buffer pages in */
 	memset(pagebuf, 0, PAGE_SIZE * 256);
 
-- 
2.31.1