diff mbox series

[kvm-unit-tests,3/3] s390x: pv: Add IPL reset tests

Message ID 20230201084833.39846-4-frankja@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series s390x: Add PV SIE intercepts and ipl tests | expand

Commit Message

Janosch Frank Feb. 1, 2023, 8:48 a.m. UTC
The diag308 requires extensive cooperation between the hypervisor and
the Ultravisor so the Ultravisor can make sure all necessary reset
steps have been done.

Let's check if we get the correct validity errors.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 s390x/Makefile                           |   2 +
 s390x/pv-ipl.c                           | 237 +++++++++++++++++++++++
 s390x/snippets/asm/snippet-pv-diag-308.S |  67 +++++++
 3 files changed, 306 insertions(+)
 create mode 100644 s390x/pv-ipl.c
 create mode 100644 s390x/snippets/asm/snippet-pv-diag-308.S

Comments

Claudio Imbrenda Feb. 17, 2023, 4:42 p.m. UTC | #1
On Wed,  1 Feb 2023 08:48:33 +0000
Janosch Frank <frankja@linux.ibm.com> wrote:

> The diag308 requires extensive cooperation between the hypervisor and
> the Ultravisor so the Ultravisor can make sure all necessary reset
> steps have been done.
> 
> Let's check if we get the correct validity errors.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---

[...]

> +
> +	/*
> +	 * We need to perform several UV calls to emulate the subcode
> +	 * 1. Failing to do that should result in a validity
> +	 *
> +	 * - Mark all cpus as stopped
> +	 * - Reset the cpus, calling one gets an initial reset
> +	 * - Load the reset PSW
> +	 * - Unshare all
> +	 * - Load the reset PSW

you forgot to mention prepare the reset, and the list does not reflect
the order things are done in the code

> +	 */
> +	sie_expect_validity(&vm);
> +	sie(&vm);
> +	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity no UVCs");
> +
> +	/* Mark the CPU as stopped so we can unshare and reset */
> +	cc = uv_set_cpu_state(vm.sblk->pv_handle_cpu, PV_CPU_STATE_STP);
> +	report(!cc, "Set cpu stopped");
> +
> +	sie_expect_validity(&vm);
> +	sie(&vm);
> +	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity stopped");
> +
> +	/* Unshare all memory */
> +	cc = uv_cmd_nodata(vm.sblk->pv_handle_config,
> +			   UVC_CMD_SET_UNSHARED_ALL, &rc, &rrc);
> +	report(cc == 0 && rc == 1, "Unshare all");
> +
> +	sie_expect_validity(&vm);
> +	sie(&vm);
> +	report((sie_get_validity(&vm) & 0xff00) == 0x2000,
> +	       "validity stopped, unshared");
> +
> +	/* Prepare the CPU reset */
> +	cc = uv_cmd_nodata(vm.sblk->pv_handle_config,
> +			   UVC_CMD_PREPARE_RESET, &rc, &rrc);
> +	report(cc == 0 && rc == 1, "Prepare reset call");
> +
> +	sie_expect_validity(&vm);
> +	sie(&vm);
> +	report((sie_get_validity(&vm) & 0xff00) == 0x2000,
> +	       "validity stopped, unshared, prepare");
> +
> +	/* Do the reset */
> +	cc = uv_cmd_nodata(vm.sblk->pv_handle_cpu,
> +			   UVC_CMD_CPU_RESET_INITIAL, &rc, &rrc);
> +	report(cc == 0 && rc == 1, "Clear reset cpu");
> +
> +	sie_expect_validity(&vm);
> +	sie(&vm);
> +	report((sie_get_validity(&vm) & 0xff00) == 0x2000,
> +	       "validity stopped, unshared, prepare, reset");
> +
> +	/* Load the PSW from 0x0 */
> +	cc = uv_set_cpu_state(vm.sblk->pv_handle_cpu, PV_CPU_STATE_OPR_LOAD);
> +	report(!cc, "Set cpu load");
> +
> +	/*
> +	 * Check if we executed the iaddr of the reset PSW, we should
> +	 * see a diagnose 0x9c PV instruction notification.
> +	 */
> +	sie(&vm);
> +	report(vm.sblk->icptcode == ICPT_PV_NOTIFY && vm.sblk->ipa == 0x8302 &&
> +	       vm.sblk->ipb == 0x50000000 && vm.save_area.guest.grs[5] == 0x9c &&
> +	       vm.save_area.guest.grs[0] == 42,
> +	       "intercept values after diag 0x308");
> +
> +
> +	uv_destroy_guest(&vm);
> +	report_prefix_pop();
> +}
> +

[...]

> diff --git a/s390x/snippets/asm/snippet-pv-diag-308.S b/s390x/snippets/asm/snippet-pv-diag-308.S
> new file mode 100644
> index 00000000..58c96173
> --- /dev/null
> +++ b/s390x/snippets/asm/snippet-pv-diag-308.S
> @@ -0,0 +1,67 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Diagnose 0x308 snippet used for PV IPL and reset testing
> + *
> + * Copyright (c) 2023 IBM Corp
> + *
> + * Authors:
> + *  Janosch Frank <frankja@linux.ibm.com>
> + */
> +#include <asm/asm-offsets.h>
> +.section .text
> +
> +/* Sets a reset PSW with the given PSW address */
> +.macro SET_RESET_PSW_ADDR label
> +lgrl	%r5, reset_psw
> +larl	%r6, \label
> +ogr	%r5, %r6
> +stg	%r5, 0
> +.endm
> +
> +/* Does a diagnose 308 with the given subcode */
> +.macro DIAG308 subcode
> +xgr	%r3, %r3
> +lghi	%r3, \subcode
> +diag	1, 3, 0x308
> +.endm
> +
> +sam64
> +
> +/* Execute the diag500 which will set the subcode we execute in gr2 */
> +diag	0, 0, 0x500
> +
> +/*
> + * A valid PGM new PSW can be a real problem since we never fall out
> + * of SIE and therefore effectively loop forever. 0 is a valid PSW
> + * therefore we re-use the reset_psw as this has the short PSW
> + * bit set which is invalid for a long PSW like the exception new
> + * PSWs.
> + *
> + * For subcode 0/1 there are no PGMs to consider.
> + */
> +lgrl   %r5, reset_psw
> +stg    %r5, GEN_LC_PGM_NEW_PSW
> +
> +/* Clean registers that are used */
> +xgr	%r0, %r0
> +xgr	%r1, %r1
> +xgr	%r3, %r3
> +xgr	%r4, %r4
> +xgr	%r5, %r5
> +xgr	%r6, %r6
> +
> +/* Subcode 0 - Modified Clear */

what about subcode 1?

> +SET_RESET_PSW_ADDR done
> +diag	%r0, %r2, 0x308
> +
> +/* Should never be executed because of the reset PSW */
> +diag	0, 0, 0x44
> +
> +done:
> +lghi	%r1, 42
> +diag	%r1, 0, 0x9c
> +
> +
> +	.align	8
> +reset_psw:
> +	.quad	0x0008000180000000
Janosch Frank Feb. 21, 2023, 9:26 a.m. UTC | #2
On 2/17/23 17:42, Claudio Imbrenda wrote:
> On Wed,  1 Feb 2023 08:48:33 +0000
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> The diag308 requires extensive cooperation between the hypervisor and
>> the Ultravisor so the Ultravisor can make sure all necessary reset
>> steps have been done.
>>
>> Let's check if we get the correct validity errors.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
> 
> [...]
> 
>> +
>> +	/*
>> +	 * We need to perform several UV calls to emulate the subcode
>> +	 * 1. Failing to do that should result in a validity
>> +	 *
>> +	 * - Mark all cpus as stopped
>> +	 * - Reset the cpus, calling one gets an initial reset
>> +	 * - Load the reset PSW
>> +	 * - Unshare all
>> +	 * - Load the reset PSW
> 
> you forgot to mention prepare the reset, and the list does not reflect
> the order things are done in the code

Ok


> [...]

>> +/* Execute the diag500 which will set the subcode we execute in gr2 */
>> +diag	0, 0, 0x500
>> +
>> +/*
>> + * A valid PGM new PSW can be a real problem since we never fall out
>> + * of SIE and therefore effectively loop forever. 0 is a valid PSW
>> + * therefore we re-use the reset_psw as this has the short PSW
>> + * bit set which is invalid for a long PSW like the exception new
>> + * PSWs.
>> + *
>> + * For subcode 0/1 there are no PGMs to consider.
>> + */
>> +lgrl   %r5, reset_psw
>> +stg    %r5, GEN_LC_PGM_NEW_PSW
>> +
>> +/* Clean registers that are used */
>> +xgr	%r0, %r0
>> +xgr	%r1, %r1
>> +xgr	%r3, %r3
>> +xgr	%r4, %r4
>> +xgr	%r5, %r5
>> +xgr	%r6, %r6
>> +
>> +/* Subcode 0 - Modified Clear */
> 
> what about subcode 1?

My guess is that this hasn't been removed after a re-work of the code.
I suggest to remove the comment.

> 
>> +SET_RESET_PSW_ADDR done
>> +diag	%r0, %r2, 0x308
>> +
>> +/* Should never be executed because of the reset PSW */
>> +diag	0, 0, 0x44
>> +
>> +done:
>> +lghi	%r1, 42
>> +diag	%r1, 0, 0x9c
>> +
>> +
>> +	.align	8
>> +reset_psw:
>> +	.quad	0x0008000180000000
>
Claudio Imbrenda Feb. 28, 2023, 5:20 p.m. UTC | #3
On Tue, 21 Feb 2023 10:26:11 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

[...]

> 
> >> +/* Execute the diag500 which will set the subcode we execute in gr2 */
> >> +diag	0, 0, 0x500
> >> +
> >> +/*
> >> + * A valid PGM new PSW can be a real problem since we never fall out
> >> + * of SIE and therefore effectively loop forever. 0 is a valid PSW
> >> + * therefore we re-use the reset_psw as this has the short PSW
> >> + * bit set which is invalid for a long PSW like the exception new
> >> + * PSWs.
> >> + *
> >> + * For subcode 0/1 there are no PGMs to consider.
> >> + */
> >> +lgrl   %r5, reset_psw
> >> +stg    %r5, GEN_LC_PGM_NEW_PSW
> >> +
> >> +/* Clean registers that are used */
> >> +xgr	%r0, %r0
> >> +xgr	%r1, %r1
> >> +xgr	%r3, %r3
> >> +xgr	%r4, %r4
> >> +xgr	%r5, %r5
> >> +xgr	%r6, %r6
> >> +
> >> +/* Subcode 0 - Modified Clear */  
> > 
> > what about subcode 1?  
> 
> My guess is that this hasn't been removed after a re-work of the code.
> I suggest to remove the comment.

sounds good

> 
> >   
> >> +SET_RESET_PSW_ADDR done
> >> +diag	%r0, %r2, 0x308
> >> +
> >> +/* Should never be executed because of the reset PSW */
> >> +diag	0, 0, 0x44
> >> +
> >> +done:
> >> +lghi	%r1, 42
> >> +diag	%r1, 0, 0x9c
> >> +
> >> +
> >> +	.align	8
> >> +reset_psw:
> >> +	.quad	0x0008000180000000  
> >   
>
diff mbox series

Patch

diff --git a/s390x/Makefile b/s390x/Makefile
index 858f5af4..e8559a4e 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -42,6 +42,7 @@  tests += $(TEST_DIR)/exittime.elf
 
 pv-tests += $(TEST_DIR)/pv-diags.elf
 pv-tests += $(TEST_DIR)/pv-icptcode.elf
+pv-tests += $(TEST_DIR)/pv-ipl.elf
 
 ifneq ($(HOST_KEY_DOCUMENT),)
 ifneq ($(GEN_SE_HEADER),)
@@ -124,6 +125,7 @@  $(TEST_DIR)/pv-icptcode.elf: pv-snippets += $(SNIPPET_DIR)/asm/snippet-pv-icpt-1
 $(TEST_DIR)/pv-icptcode.elf: pv-snippets += $(SNIPPET_DIR)/asm/snippet-pv-icpt-loop.gbin
 $(TEST_DIR)/pv-icptcode.elf: pv-snippets += $(SNIPPET_DIR)/asm/snippet-loop.gbin
 $(TEST_DIR)/pv-icptcode.elf: pv-snippets += $(SNIPPET_DIR)/asm/snippet-pv-icpt-vir-timing.gbin
+$(TEST_DIR)/pv-ipl.elf: pv-snippets += $(SNIPPET_DIR)/asm/snippet-pv-diag-308.gbin
 
 ifneq ($(GEN_SE_HEADER),)
 snippets += $(pv-snippets)
diff --git a/s390x/pv-ipl.c b/s390x/pv-ipl.c
new file mode 100644
index 00000000..61afde5c
--- /dev/null
+++ b/s390x/pv-ipl.c
@@ -0,0 +1,237 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * PV diagnose 308 (IPL) tests
+ *
+ * Copyright (c) 2023 IBM Corp
+ *
+ * Authors:
+ *  Janosch Frank <frankja@linux.ibm.com>
+ */
+#include <libcflat.h>
+#include <sie.h>
+#include <sclp.h>
+#include <snippet.h>
+#include <asm/facility.h>
+#include <asm/uv.h>
+
+static struct vm vm;
+
+static void setup_gbin(void)
+{
+	extern const char SNIPPET_NAME_START(asm, snippet_pv_diag_308)[];
+	extern const char SNIPPET_NAME_END(asm, snippet_pv_diag_308)[];
+	extern const char SNIPPET_HDR_START(asm, snippet_pv_diag_308)[];
+	extern const char SNIPPET_HDR_END(asm, snippet_pv_diag_308)[];
+	int size_hdr = SNIPPET_HDR_LEN(asm, snippet_pv_diag_308);
+	int size_gbin = SNIPPET_LEN(asm, snippet_pv_diag_308);
+
+	snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_308),
+			SNIPPET_HDR_START(asm, snippet_pv_diag_308),
+			size_gbin, size_hdr, SNIPPET_UNPACK_OFF);
+}
+
+static void test_diag_308_1(void)
+{
+	uint16_t rc, rrc;
+	int cc;
+
+	report_prefix_push("subcode 1");
+	setup_gbin();
+
+	sie(&vm);
+	report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 &&
+	       vm.sblk->ipb == 0x50000000 && vm.save_area.guest.grs[5] == 0x500,
+	       "intercept values diag 500");
+	/* The snippet asked us for the subcode and we answer with 1 in gr2 */
+	vm.save_area.guest.grs[2] = 1;
+
+	/* Continue after diag 0x500, next icpt should be the 0x308 */
+	sie(&vm);
+	report(vm.sblk->icptcode == ICPT_PV_NOTIFY && vm.sblk->ipa == 0x8302 &&
+	       vm.sblk->ipb == 0x50000000 && vm.save_area.guest.grs[5] == 0x308,
+	       "intercept values diag 0x308");
+	report(vm.save_area.guest.grs[2] == 1,
+	       "subcode 1");
+
+	/*
+	 * We need to perform several UV calls to emulate the subcode
+	 * 1. Failing to do that should result in a validity
+	 *
+	 * - Mark all cpus as stopped
+	 * - Reset the cpus, calling one gets an initial reset
+	 * - Load the reset PSW
+	 * - Unshare all
+	 * - Load the reset PSW
+	 */
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity no UVCs");
+
+	/* Mark the CPU as stopped so we can unshare and reset */
+	cc = uv_set_cpu_state(vm.sblk->pv_handle_cpu, PV_CPU_STATE_STP);
+	report(!cc, "Set cpu stopped");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity stopped");
+
+	/* Unshare all memory */
+	cc = uv_cmd_nodata(vm.sblk->pv_handle_config,
+			   UVC_CMD_SET_UNSHARED_ALL, &rc, &rrc);
+	report(cc == 0 && rc == 1, "Unshare all");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000,
+	       "validity stopped, unshared");
+
+	/* Prepare the CPU reset */
+	cc = uv_cmd_nodata(vm.sblk->pv_handle_config,
+			   UVC_CMD_PREPARE_RESET, &rc, &rrc);
+	report(cc == 0 && rc == 1, "Prepare reset call");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000,
+	       "validity stopped, unshared, prepare");
+
+	/* Do the reset */
+	cc = uv_cmd_nodata(vm.sblk->pv_handle_cpu,
+			   UVC_CMD_CPU_RESET_INITIAL, &rc, &rrc);
+	report(cc == 0 && rc == 1, "Clear reset cpu");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000,
+	       "validity stopped, unshared, prepare, reset");
+
+	/* Load the PSW from 0x0 */
+	cc = uv_set_cpu_state(vm.sblk->pv_handle_cpu, PV_CPU_STATE_OPR_LOAD);
+	report(!cc, "Set cpu load");
+
+	/*
+	 * Check if we executed the iaddr of the reset PSW, we should
+	 * see a diagnose 0x9c PV instruction notification.
+	 */
+	sie(&vm);
+	report(vm.sblk->icptcode == ICPT_PV_NOTIFY && vm.sblk->ipa == 0x8302 &&
+	       vm.sblk->ipb == 0x50000000 && vm.save_area.guest.grs[5] == 0x9c &&
+	       vm.save_area.guest.grs[0] == 42,
+	       "intercept values after diag 0x308");
+
+
+	uv_destroy_guest(&vm);
+	report_prefix_pop();
+}
+
+static void test_diag_308_0(void)
+{
+	uint16_t rc, rrc;
+	int cc;
+
+	report_prefix_push("subcode 0");
+	setup_gbin();
+
+	sie(&vm);
+	report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 &&
+	       vm.sblk->ipb == 0x50000000 && vm.save_area.guest.grs[5] == 0x500,
+	       "intercept values diag 500");
+	/* The snippet asked us for the subcode and we answer with 0 in gr2 */
+	vm.save_area.guest.grs[2] = 0;
+
+	/* Continue after diag 0x500, next icpt should be the 0x308 */
+	sie(&vm);
+	report(vm.sblk->icptcode == ICPT_PV_NOTIFY && vm.sblk->ipa == 0x8302 &&
+	       vm.sblk->ipb == 0x50000000 && vm.save_area.guest.grs[5] == 0x308,
+	       "intercept values");
+	report(vm.save_area.guest.grs[2] == 0,
+	       "subcode 0");
+
+	/*
+	 * We need to perform several UV calls to emulate the subcode
+	 * 0. Failing to do that should result in a validity
+	 *
+	 * - Mark all cpus as stopped
+	 * - Unshare all memory
+	 * - Prepare the reset
+	 * - Reset the cpus
+	 * - Load the reset PSW
+	 */
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity, no action");
+
+	/* Mark the CPU as stopped so we can unshare and reset */
+	cc = uv_set_cpu_state(vm.sblk->pv_handle_cpu, PV_CPU_STATE_STP);
+	report(!cc, "Set cpu stopped");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity, stopped");
+
+	/* Unshare all memory */
+	cc = uv_cmd_nodata(vm.sblk->pv_handle_config,
+			   UVC_CMD_SET_UNSHARED_ALL, &rc, &rrc);
+	report(cc == 0 && rc == 1, "Unshare all");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity stopped, unshared");
+
+	/* Prepare the CPU reset */
+	cc = uv_cmd_nodata(vm.sblk->pv_handle_config,
+			   UVC_CMD_PREPARE_RESET, &rc, &rrc);
+	report(cc == 0 && rc == 1, "Prepare reset call");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity stopped, unshared, prep reset");
+
+	/* Do the reset */
+	cc = uv_cmd_nodata(vm.sblk->pv_handle_cpu,
+			   UVC_CMD_CPU_RESET_CLEAR, &rc, &rrc);
+	report(cc == 0 && rc == 1, "Clear reset cpu");
+
+	sie_expect_validity(&vm);
+	sie(&vm);
+	report((sie_get_validity(&vm) & 0xff00) == 0x2000, "validity stopped, unshared, prep reset, cpu reset");
+
+	/* Load the PSW from 0x0 */
+	cc = uv_set_cpu_state(vm.sblk->pv_handle_cpu, PV_CPU_STATE_OPR_LOAD);
+	report(!cc, "Set cpu load");
+
+	/*
+	 * Check if we executed the iaddr of the reset PSW, we should
+	 * see a diagnose 0x9c PV instruction notification.
+	 */
+	sie(&vm);
+	report(vm.sblk->icptcode == ICPT_PV_NOTIFY && vm.sblk->ipa == 0x8302 &&
+	       vm.sblk->ipb == 0x50000000 && vm.save_area.guest.grs[5] == 0x9c &&
+	       vm.save_area.guest.grs[0] == 42,
+	       "intercept values");
+
+	uv_destroy_guest(&vm);
+	report_prefix_pop();
+}
+
+int main(void)
+{
+	report_prefix_push("uv-sie");
+	if (!test_facility(158)) {
+		report_skip("UV Call facility unavailable");
+		goto done;
+	}
+	if (!sclp_facilities.has_sief2) {
+		report_skip("SIEF2 facility unavailable");
+		goto done;
+	}
+
+	snippet_setup_guest(&vm, true);
+	test_diag_308_0();
+	test_diag_308_1();
+	sie_guest_destroy(&vm);
+
+done:
+	report_prefix_pop();
+	return report_summary();
+}
diff --git a/s390x/snippets/asm/snippet-pv-diag-308.S b/s390x/snippets/asm/snippet-pv-diag-308.S
new file mode 100644
index 00000000..58c96173
--- /dev/null
+++ b/s390x/snippets/asm/snippet-pv-diag-308.S
@@ -0,0 +1,67 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Diagnose 0x308 snippet used for PV IPL and reset testing
+ *
+ * Copyright (c) 2023 IBM Corp
+ *
+ * Authors:
+ *  Janosch Frank <frankja@linux.ibm.com>
+ */
+#include <asm/asm-offsets.h>
+.section .text
+
+/* Sets a reset PSW with the given PSW address */
+.macro SET_RESET_PSW_ADDR label
+lgrl	%r5, reset_psw
+larl	%r6, \label
+ogr	%r5, %r6
+stg	%r5, 0
+.endm
+
+/* Does a diagnose 308 with the given subcode */
+.macro DIAG308 subcode
+xgr	%r3, %r3
+lghi	%r3, \subcode
+diag	1, 3, 0x308
+.endm
+
+sam64
+
+/* Execute the diag500 which will set the subcode we execute in gr2 */
+diag	0, 0, 0x500
+
+/*
+ * A valid PGM new PSW can be a real problem since we never fall out
+ * of SIE and therefore effectively loop forever. 0 is a valid PSW
+ * therefore we re-use the reset_psw as this has the short PSW
+ * bit set which is invalid for a long PSW like the exception new
+ * PSWs.
+ *
+ * For subcode 0/1 there are no PGMs to consider.
+ */
+lgrl   %r5, reset_psw
+stg    %r5, GEN_LC_PGM_NEW_PSW
+
+/* Clean registers that are used */
+xgr	%r0, %r0
+xgr	%r1, %r1
+xgr	%r3, %r3
+xgr	%r4, %r4
+xgr	%r5, %r5
+xgr	%r6, %r6
+
+/* Subcode 0 - Modified Clear */
+SET_RESET_PSW_ADDR done
+diag	%r0, %r2, 0x308
+
+/* Should never be executed because of the reset PSW */
+diag	0, 0, 0x44
+
+done:
+lghi	%r1, 42
+diag	%r1, 0, 0x9c
+
+
+	.align	8
+reset_psw:
+	.quad	0x0008000180000000