selftests: kvm: s390: Add VM run test case

Add test case running code interacting with registers within a
ucontrol VM.

* Add uc_gprs test case

The test uses the same VM setup using the fixture and debug macros
introduced in earlier patches in this series.
Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20240807154512.316936-7-schlameuss@linux.ibm.com
[frankja@linux.ibm.com: Removed leftover comment line]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20240807154512.316936-7-schlameuss@linux.ibm.com>

tools/testing/selftests/kvm/s390x/ucontrol_test.c

@@ -7,6 +7,7 @@
  * Authors:
  *  Christoph Schlameuss <schlameuss@linux.ibm.com>
  */
+#include "debug_print.h"
 #include "kselftest_harness.h"
 #include "kvm_util.h"
 #include "processor.h"
@@ -40,6 +41,23 @@ void require_ucontrol_admin(void)
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_S390_UCONTROL));
 }
 
+/* Test program setting some registers and looping */
+extern char test_gprs_asm[];
+asm("test_gprs_asm:\n"
+	"xgr	%r0, %r0\n"
+	"lgfi	%r1,1\n"
+	"lgfi	%r2,2\n"
+	"lgfi	%r3,3\n"
+	"lgfi	%r4,4\n"
+	"lgfi	%r5,5\n"
+	"lgfi	%r6,6\n"
+	"lgfi	%r7,7\n"
+	"0:\n"
+	"	diag	0,0,0x44\n"
+	"	ahi	%r0,1\n"
+	"	j	0b\n"
+);
+
 FIXTURE(uc_kvm)
 {
 	struct kvm_s390_sie_block *sie_block;
@@ -204,4 +222,111 @@ TEST(uc_cap_hpage)
 	close(kvm_fd);
 }
 
+/* verify SIEIC exit
+ * * fail on codes not expected in the test cases
+ */
+static bool uc_handle_sieic(FIXTURE_DATA(uc_kvm) * self)
+{
+	struct kvm_s390_sie_block *sie_block = self->sie_block;
+	struct kvm_run *run = self->run;
+
+	/* check SIE interception code */
+	pr_info("sieic: 0x%.2x 0x%.4x 0x%.4x\n",
+		run->s390_sieic.icptcode,
+		run->s390_sieic.ipa,
+		run->s390_sieic.ipb);
+	switch (run->s390_sieic.icptcode) {
+	case ICPT_INST:
+		/* end execution in caller on intercepted instruction */
+		pr_info("sie instruction interception\n");
+		return false;
+	case ICPT_OPEREXC:
+		/* operation exception */
+		TEST_FAIL("sie exception on %.4x%.8x", sie_block->ipa, sie_block->ipb);
+	default:
+		TEST_FAIL("UNEXPECTED SIEIC CODE %d", run->s390_sieic.icptcode);
+	}
+	return true;
+}
+
+/* verify VM state on exit */
+static bool uc_handle_exit(FIXTURE_DATA(uc_kvm) * self)
+{
+	struct kvm_run *run = self->run;
+
+	switch (run->exit_reason) {
+	case KVM_EXIT_S390_SIEIC:
+		return uc_handle_sieic(self);
+	default:
+		pr_info("exit_reason %2d not handled\n", run->exit_reason);
+	}
+	return true;
+}
+
+/* run the VM until interrupted */
+static int uc_run_once(FIXTURE_DATA(uc_kvm) * self)
+{
+	int rc;
+
+	rc = ioctl(self->vcpu_fd, KVM_RUN, NULL);
+	print_run(self->run, self->sie_block);
+	print_regs(self->run);
+	pr_debug("run %d / %d %s\n", rc, errno, strerror(errno));
+	return rc;
+}
+
+static void uc_assert_diag44(FIXTURE_DATA(uc_kvm) * self)
+{
+	struct kvm_s390_sie_block *sie_block = self->sie_block;
+
+	/* assert vm was interrupted by diag 0x0044 */
+	TEST_ASSERT_EQ(KVM_EXIT_S390_SIEIC, self->run->exit_reason);
+	TEST_ASSERT_EQ(ICPT_INST, sie_block->icptcode);
+	TEST_ASSERT_EQ(0x8300, sie_block->ipa);
+	TEST_ASSERT_EQ(0x440000, sie_block->ipb);
+}
+
+TEST_F(uc_kvm, uc_gprs)
+{
+	struct kvm_sync_regs *sync_regs = &self->run->s.regs;
+	struct kvm_run *run = self->run;
+	struct kvm_regs regs = {};
+
+	/* Set registers to values that are different from the ones that we expect below */
+	for (int i = 0; i < 8; i++)
+		sync_regs->gprs[i] = 8;
+	run->kvm_dirty_regs |= KVM_SYNC_GPRS;
+
+	/* copy test_gprs_asm to code_hva / code_gpa */
+	TH_LOG("copy code %p to vm mapped memory %p / %p",
+	       &test_gprs_asm, (void *)self->code_hva, (void *)self->code_gpa);
+	memcpy((void *)self->code_hva, &test_gprs_asm, PAGE_SIZE);
+
+	/* DAT disabled + 64 bit mode */
+	run->psw_mask = 0x0000000180000000ULL;
+	run->psw_addr = self->code_gpa;
+
+	/* run and expect interception of diag 44 */
+	ASSERT_EQ(0, uc_run_once(self));
+	ASSERT_EQ(false, uc_handle_exit(self));
+	uc_assert_diag44(self);
+
+	/* Retrieve and check guest register values */
+	ASSERT_EQ(0, ioctl(self->vcpu_fd, KVM_GET_REGS, &regs));
+	for (int i = 0; i < 8; i++) {
+		ASSERT_EQ(i, regs.gprs[i]);
+		ASSERT_EQ(i, sync_regs->gprs[i]);
+	}
+
+	/* run and expect interception of diag 44 again */
+	ASSERT_EQ(0, uc_run_once(self));
+	ASSERT_EQ(false, uc_handle_exit(self));
+	uc_assert_diag44(self);
+
+	/* check continued increment of register 0 value */
+	ASSERT_EQ(0, ioctl(self->vcpu_fd, KVM_GET_REGS, &regs));
+	ASSERT_EQ(1, regs.gprs[0]);
+	ASSERT_EQ(1, sync_regs->gprs[0]);
+}
+
 TEST_HARNESS_MAIN