[kvm-unit-tests PATCH 0/3] s390x: Add test for STFLE interpretive execution (format-2)

[kvm-unit-tests PATCH 0/3] s390x: Add test for STFLE interpretive execution (format-2)

[Christoph Schlameuss]

Test the shadowing of format-2 facility list when running in VSIE.

The tests will skip the format 2 tests
* if running with unpatched kernels or qemu in G1 or G2
* if running on machines prior IBM z16 GA1 (where ASTFLEIE2 is not
  available)

Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: "Nico Böhr" <nrb@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
To: linux-s390@vger.kernel.org
Cc: kvm@vger.kernel.org

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
The original series was started by Nina and finished by me.

---
Nina Schoetterl-Glausch (3):
      s390x: snippets: Add reset_guest() to lib
      s390x: sclp: Add detection of alternate STFLE facilities
      s390x: Add test for STFLE interpretive execution (format-2)

 lib/s390x/sclp.c    |  2 ++
 lib/s390x/sclp.h    |  6 +++-
 lib/s390x/sie.c     | 11 +++++++
 lib/s390x/sie.h     |  1 +
 lib/s390x/snippet.h |  6 ++++
 s390x/spec_ex-sie.c | 10 ++----
 s390x/stfle-sie.c   | 91 ++++++++++++++++++++++++++++++++++++++++++++++-------
 7 files changed, 107 insertions(+), 20 deletions(-)
---
base-commit: 86e53277ac80dabb04f4fa5fa6a6cc7649392bdc
change-id: 20260202-vsie-stfle-fac-403e4467d8e2

Best regards,
-- 
Christoph Schlameuss <schlameuss@linux.ibm.com>

[kvm-unit-tests PATCH 1/3] s390x: snippets: Add reset_guest() to lib

[Christoph Schlameuss]

From: Nina Schoetterl-Glausch <nsg@linux.ibm.com>

Extract reset_guest from spec_ex-sie into the lib.
After reset_guest() the snippet can be executed again.

Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 lib/s390x/snippet.h |  6 ++++++
 s390x/spec_ex-sie.c | 10 ++--------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/s390x/snippet.h b/lib/s390x/snippet.h
index 910849aa186ce2f94c64ac1f40f8d6d7cdc36a1f..6f611de510d832f23384739606da13e71de3d6fd 100644
--- a/lib/s390x/snippet.h
+++ b/lib/s390x/snippet.h
@@ -83,6 +83,12 @@ static inline void snippet_init(struct vm *vm, const char *gbin,
 	vm->sblk->ictl = ICTL_OPEREXC | ICTL_PINT;
 }
 
+static inline void reset_guest(struct vm *vm)
+{
+	vm->sblk->gpsw = snippet_psw;
+	vm->sblk->icptcode = 0;
+}
+
 /*
  * Sets up a snippet UV/PV guest on top of an existing and initialized
  * SIE vm struct.
diff --git a/s390x/spec_ex-sie.c b/s390x/spec_ex-sie.c
index fe2f23ee3d84fa144416808cb4b353627fe87f3d..75625ecffc4a5a09ff7ef6136b7f1120a831a8c5 100644
--- a/s390x/spec_ex-sie.c
+++ b/s390x/spec_ex-sie.c
@@ -31,12 +31,6 @@ static void setup_guest(void)
 		     SNIPPET_LEN(c, spec_ex), SNIPPET_UNPACK_OFF);
 }
 
-static void reset_guest(void)
-{
-	vm.sblk->gpsw = snippet_psw;
-	vm.sblk->icptcode = 0;
-}
-
 static void test_spec_ex_sie(void)
 {
 	const char *msg;
@@ -45,7 +39,7 @@ static void test_spec_ex_sie(void)
 
 	report_prefix_push("SIE spec ex interpretation");
 	report_prefix_push("off");
-	reset_guest();
+	reset_guest(&vm);
 	sie(&vm);
 	/* interpretation off -> initial exception must cause interception */
 	report(vm.sblk->icptcode == ICPT_PROGI
@@ -56,7 +50,7 @@ static void test_spec_ex_sie(void)
 
 	report_prefix_push("on");
 	vm.sblk->ecb |= ECB_SPECI;
-	reset_guest();
+	reset_guest(&vm);
 	sie(&vm);
 	/* interpretation on -> configuration dependent if initial exception causes
 	 * interception, but invalid new program PSW must

-- 
2.53.0

[kvm-unit-tests PATCH 2/3] s390x: sclp: Add detection of alternate STFLE facilities

[Christoph Schlameuss]

From: Nina Schoetterl-Glausch <nsg@linux.ibm.com>

Detect availability of alternate STFLE interpretive execution facilities
1 and 2.
Also fix number of unassigned bits in sclp_facilities which wasn't
adjusted in a prior commit adding entries to sclp_facilities.

Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 lib/s390x/sclp.c | 2 ++
 lib/s390x/sclp.h | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 2f902e39e785ff4e139a39be2ffe11b5fa01edc0..7408b813b6396d572d740c19c15175e173fed596 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -163,8 +163,10 @@ void sclp_facilities_setup(void)
 	sclp_facilities.has_cmma = sclp_feat_check(116, SCLP_FEAT_116_BIT_CMMA);
 	sclp_facilities.has_64bscao = sclp_feat_check(116, SCLP_FEAT_116_BIT_64BSCAO);
 	sclp_facilities.has_esca = sclp_feat_check(116, SCLP_FEAT_116_BIT_ESCA);
+	sclp_facilities.has_astfleie1 = sclp_feat_check(116, SCLP_FEAT_116_BIT_ASTFLEIE1);
 	sclp_facilities.has_ibs = sclp_feat_check(117, SCLP_FEAT_117_BIT_IBS);
 	sclp_facilities.has_pfmfi = sclp_feat_check(117, SCLP_FEAT_117_BIT_PFMFI);
+	sclp_facilities.has_astfleie2 = sclp_feat_check(139, SCLP_FEAT_139_BIT_ASTFLEIE2);
 
 	for (i = 0; i < read_info->entries_cpu; i++, cpu++) {
 		/*
diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index 22f120d1b7ea7d1c3fe822385d0c689e5b3459fe..91a81c902eaa8ee6b999184aeb8a33633efd1065 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -129,10 +129,12 @@ struct sclp_facilities {
 	uint64_t has_cmma : 1;
 	uint64_t has_64bscao : 1;
 	uint64_t has_esca : 1;
+	uint64_t has_astfleie1 : 1;
 	uint64_t has_kss : 1;
 	uint64_t has_pfmfi : 1;
 	uint64_t has_ibs : 1;
-	uint64_t : 64 - 15;
+	uint64_t has_astfleie2 : 1;
+	uint64_t : 64 - 19;
 };
 
 /* bit number within a certain byte */
@@ -143,8 +145,10 @@ struct sclp_facilities {
 #define SCLP_FEAT_116_BIT_64BSCAO	0
 #define SCLP_FEAT_116_BIT_CMMA		1
 #define SCLP_FEAT_116_BIT_ESCA		4
+#define SCLP_FEAT_116_BIT_ASTFLEIE1	7
 #define SCLP_FEAT_117_BIT_PFMFI		1
 #define SCLP_FEAT_117_BIT_IBS		2
+#define SCLP_FEAT_139_BIT_ASTFLEIE2	1
 
 typedef struct ReadInfo {
 	SCCBHeader h;

-- 
2.53.0

[kvm-unit-tests PATCH 3/3] s390x: Add test for STFLE interpretive execution (format-2)

[Christoph Schlameuss]

From: Nina Schoetterl-Glausch <nsg@linux.ibm.com>

The STFLE instruction indicates installed facilities.
SIE has facilities for the interpretive execution of STFLE.
There are multiple possible formats for the control block.
Use a snippet guest executing STFLE to get the result of
interpretive execution and check the result.
With the addition of the format-2 control block invalid format
specifiers are now possible.
Test for the occurrence of optional validity intercepts.

Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 lib/s390x/sie.c   | 11 +++++++
 lib/s390x/sie.h   |  1 +
 s390x/stfle-sie.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 92 insertions(+), 11 deletions(-)

diff --git a/lib/s390x/sie.c b/lib/s390x/sie.c
index 0fa915cf028a1b35a76aa316dfd97308094a4682..17f0ef7eff427002dd6d74d98f58ed493457a7ce 100644
--- a/lib/s390x/sie.c
+++ b/lib/s390x/sie.c
@@ -42,6 +42,17 @@ void sie_check_validity(struct vm *vm, uint16_t vir_exp)
 	report(vir_exp == vir, "VALIDITY: %x", vir);
 }
 
+void sie_check_optional_validity(struct vm *vm, uint16_t vir_exp)
+{
+	uint16_t vir = sie_get_validity(vm);
+
+	if (vir == 0xffff)
+		report_pass("optional VALIDITY: no");
+	else
+		report(vir_exp == vir, "optional VALIDITY: %x", vir);
+	vm->validity_expected = false;
+}
+
 void sie_handle_validity(struct vm *vm)
 {
 	if (vm->sblk->icptcode != ICPT_VALIDITY)
diff --git a/lib/s390x/sie.h b/lib/s390x/sie.h
index 3ec49ed0da6459a70689ce5a1a8a027a4113f2a4..8bea0b10b0a6894096ee83933a8bda11711a1949 100644
--- a/lib/s390x/sie.h
+++ b/lib/s390x/sie.h
@@ -51,6 +51,7 @@ void sie(struct vm *vm);
 void sie_expect_validity(struct vm *vm);
 uint16_t sie_get_validity(struct vm *vm);
 void sie_check_validity(struct vm *vm, uint16_t vir_exp);
+void sie_check_optional_validity(struct vm *vm, uint16_t vir_exp);
 void sie_handle_validity(struct vm *vm);
 
 static inline bool sie_is_pv(struct vm *vm)
diff --git a/s390x/stfle-sie.c b/s390x/stfle-sie.c
index 21cf8ff8b6f6e9d61ee304c5748c36f718da65ab..5b642d9e8c3d775e078c1f09b87ad6822cd28a32 100644
--- a/s390x/stfle-sie.c
+++ b/s390x/stfle-sie.c
@@ -42,6 +42,7 @@ static struct guest_stfle_res run_guest(void)
 	uint64_t guest_stfle_addr;
 	uint64_t reg;
 
+	reset_guest(&vm);
 	sie(&vm);
 	assert(snippet_is_force_exit_value(&vm));
 	guest_stfle_addr = snippet_get_force_exit_value(&vm);
@@ -55,18 +56,73 @@ static struct guest_stfle_res run_guest(void)
 static void test_stfle_format_0(void)
 {
 	struct guest_stfle_res res;
+	int format_mask;
 
 	report_prefix_push("format-0");
-	for (int j = 0; j < stfle_size(); j++)
-		WRITE_ONCE((*fac)[j], prng64(&prng_s));
-	vm.sblk->fac = (uint32_t)(uint64_t)fac;
-	res = run_guest();
-	report(res.len == stfle_size(), "stfle len correct");
-	report(!memcmp(*fac, res.mem, res.len * sizeof(uint64_t)),
-	       "Guest facility list as specified");
+	/*
+	 * There are multiple valid two bit format control values depending on
+	 * the available facilities.
+	 * The facility introduced last defines the validity of control bits.
+	 */
+	format_mask = sclp_facilities.has_astfleie2 ? 3 : sclp_facilities.has_astfleie1;
+	for (int i = 0; i < 4; i++) {
+		if (i & format_mask)
+			continue;
+		report_prefix_pushf("format control %d", i);
+		for (int j = 0; j < stfle_size(); j++)
+			WRITE_ONCE((*fac)[j], prng64(&prng_s));
+		vm.sblk->fac = (uint32_t)(uint64_t)fac | i;
+		res = run_guest();
+		report(res.len == stfle_size(), "stfle len correct");
+		report(!memcmp(*fac, res.mem, res.len * sizeof(uint64_t)),
+		       "Guest facility list as specified");
+		report_prefix_pop();
+	}
 	report_prefix_pop();
 }
 
+static void test_stfle_format_2(void)
+{
+	const int max_stfle_len = 8;
+	int guest_max_stfle_len = 0;
+	struct guest_stfle_res res;
+	bool saturated = false;
+
+	report_prefix_push("format-2");
+	for (int i = 1; i <= max_stfle_len; i++) {
+		report_prefix_pushf("max STFLE len %d", i);
+
+		WRITE_ONCE((*fac)[0], i - 1);
+		for (int j = 0; j < i; j++)
+			WRITE_ONCE((*fac)[j + 1], prng64(&prng_s));
+		vm.sblk->fac = (uint32_t)(uint64_t)fac | 2;
+		res = run_guest();
+		/* len increases up to maximum (machine specific) */
+		if (res.len < i)
+			saturated = true;
+		if (saturated) {
+			report(res.len == guest_max_stfle_len, "stfle len correct");
+		} else {
+			report(res.len == i, "stfle len correct");
+			guest_max_stfle_len = i;
+		}
+		report(!memcmp(&(*fac)[1], res.mem, guest_max_stfle_len * sizeof(uint64_t)),
+		       "Guest facility list as specified");
+
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+}
+
+static void test_no_stfle_format(int format)
+{
+	reset_guest(&vm);
+	vm.sblk->fac = (uint32_t)(uint64_t)fac | format;
+	sie_expect_validity(&vm);
+	sie(&vm);
+	sie_check_optional_validity(&vm, 0x1330);
+}
+
 struct args {
 	uint64_t seed;
 };
@@ -119,20 +175,33 @@ static struct args parse_args(int argc, char **argv)
 int main(int argc, char **argv)
 {
 	struct args args = parse_args(argc, argv);
-	bool run_format_0 = test_facility(7);
 
 	if (!sclp_facilities.has_sief2) {
 		report_skip("SIEF2 facility unavailable");
 		goto out;
 	}
-	if (!run_format_0)
+	if (!test_facility(7)) {
 		report_skip("STFLE facility not available");
+		goto out;
+	}
 
 	report_info("PRNG seed: 0x%lx", args.seed);
 	prng_s = prng_init(args.seed);
 	setup_guest();
-	if (run_format_0)
-		test_stfle_format_0();
+	test_stfle_format_0();
+
+	if (!sclp_facilities.has_astfleie1)
+		test_no_stfle_format(1);
+
+	if (!sclp_facilities.has_astfleie2) {
+		test_no_stfle_format(2);
+		report_skip("alternate STFLE interpretive-execution facility 2 not available");
+	} else {
+		test_stfle_format_2();
+	}
+
+	test_no_stfle_format(3);
+
 out:
 	return report_summary();
 }

-- 
2.53.0

Re: [kvm-unit-tests PATCH 1/3] s390x: snippets: Add reset_guest() to lib

[Janosch Frank]

On 2/11/26 15:57, Christoph Schlameuss wrote:
> From: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
> 
> Extract reset_guest from spec_ex-sie into the lib.
> After reset_guest() the snippet can be executed again.
> 
> Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

Re: [kvm-unit-tests PATCH 2/3] s390x: sclp: Add detection of alternate STFLE facilities

[Janosch Frank]

On 2/11/26 15:57, Christoph Schlameuss wrote:
> From: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
> 
> Detect availability of alternate STFLE interpretive execution facilities
> 1 and 2.
> Also fix number of unassigned bits in sclp_facilities which wasn't
> adjusted in a prior commit adding entries to sclp_facilities.
> 
> Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>   lib/s390x/sclp.c | 2 ++
>   lib/s390x/sclp.h | 6 +++++-
>   2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> index 2f902e39e785ff4e139a39be2ffe11b5fa01edc0..7408b813b6396d572d740c19c15175e173fed596 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -163,8 +163,10 @@ void sclp_facilities_setup(void)
>   	sclp_facilities.has_cmma = sclp_feat_check(116, SCLP_FEAT_116_BIT_CMMA);
>   	sclp_facilities.has_64bscao = sclp_feat_check(116, SCLP_FEAT_116_BIT_64BSCAO);
>   	sclp_facilities.has_esca = sclp_feat_check(116, SCLP_FEAT_116_BIT_ESCA);
> +	sclp_facilities.has_astfleie1 = sclp_feat_check(116, SCLP_FEAT_116_BIT_ASTFLEIE1);
>   	sclp_facilities.has_ibs = sclp_feat_check(117, SCLP_FEAT_117_BIT_IBS);
>   	sclp_facilities.has_pfmfi = sclp_feat_check(117, SCLP_FEAT_117_BIT_PFMFI);
> +	sclp_facilities.has_astfleie2 = sclp_feat_check(139, SCLP_FEAT_139_BIT_ASTFLEIE2);
>   
>   	for (i = 0; i < read_info->entries_cpu; i++, cpu++) {
>   		/*
> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
> index 22f120d1b7ea7d1c3fe822385d0c689e5b3459fe..91a81c902eaa8ee6b999184aeb8a33633efd1065 100644
> --- a/lib/s390x/sclp.h
> +++ b/lib/s390x/sclp.h
> @@ -129,10 +129,12 @@ struct sclp_facilities {
>   	uint64_t has_cmma : 1;
>   	uint64_t has_64bscao : 1;
>   	uint64_t has_esca : 1;
> +	uint64_t has_astfleie1 : 1;
>   	uint64_t has_kss : 1;
>   	uint64_t has_pfmfi : 1;
>   	uint64_t has_ibs : 1;
> -	uint64_t : 64 - 15;
> +	uint64_t has_astfleie2 : 1;
> +	uint64_t : 64 - 19;
>   };

64 - 17?

I was wondering why the static assert didn't trigger here. Turns out I 
only added it to a feature branch that didn't go upstream yet...

Could you do me a favor and add a patch that introduces the static assert:
_Static_assert(sizeof(struct sclp_facilities) == sizeof(uint64_t));

Then again, why do we pad that at all, it's not a FW struct and I hope 
that we never cast it to u64 and copy it somewhere.

>   
>   /* bit number within a certain byte */
> @@ -143,8 +145,10 @@ struct sclp_facilities {
>   #define SCLP_FEAT_116_BIT_64BSCAO	0
>   #define SCLP_FEAT_116_BIT_CMMA		1
>   #define SCLP_FEAT_116_BIT_ESCA		4
> +#define SCLP_FEAT_116_BIT_ASTFLEIE1	7
>   #define SCLP_FEAT_117_BIT_PFMFI		1
>   #define SCLP_FEAT_117_BIT_IBS		2
> +#define SCLP_FEAT_139_BIT_ASTFLEIE2	1
>   
>   typedef struct ReadInfo {
>   	SCCBHeader h;
> 

Re: [kvm-unit-tests PATCH 2/3] s390x: sclp: Add detection of alternate STFLE facilities

[Christoph Schlameuss]

On Fri Feb 20, 2026 at 11:20 AM CET, Janosch Frank wrote:
> On 2/11/26 15:57, Christoph Schlameuss wrote:
>> From: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
>> 
>> Detect availability of alternate STFLE interpretive execution facilities
>> 1 and 2.
>> Also fix number of unassigned bits in sclp_facilities which wasn't
>> adjusted in a prior commit adding entries to sclp_facilities.
>> 
>> Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
>> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
>> ---
>>   lib/s390x/sclp.c | 2 ++
>>   lib/s390x/sclp.h | 6 +++++-
>>   2 files changed, 7 insertions(+), 1 deletion(-)
>> 
>> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
>> index 2f902e39e785ff4e139a39be2ffe11b5fa01edc0..7408b813b6396d572d740c19c15175e173fed596 100644
>> --- a/lib/s390x/sclp.c
>> +++ b/lib/s390x/sclp.c
>> @@ -163,8 +163,10 @@ void sclp_facilities_setup(void)
>>   	sclp_facilities.has_cmma = sclp_feat_check(116, SCLP_FEAT_116_BIT_CMMA);
>>   	sclp_facilities.has_64bscao = sclp_feat_check(116, SCLP_FEAT_116_BIT_64BSCAO);
>>   	sclp_facilities.has_esca = sclp_feat_check(116, SCLP_FEAT_116_BIT_ESCA);
>> +	sclp_facilities.has_astfleie1 = sclp_feat_check(116, SCLP_FEAT_116_BIT_ASTFLEIE1);
>>   	sclp_facilities.has_ibs = sclp_feat_check(117, SCLP_FEAT_117_BIT_IBS);
>>   	sclp_facilities.has_pfmfi = sclp_feat_check(117, SCLP_FEAT_117_BIT_PFMFI);
>> +	sclp_facilities.has_astfleie2 = sclp_feat_check(139, SCLP_FEAT_139_BIT_ASTFLEIE2);
>>   
>>   	for (i = 0; i < read_info->entries_cpu; i++, cpu++) {
>>   		/*
>> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
>> index 22f120d1b7ea7d1c3fe822385d0c689e5b3459fe..91a81c902eaa8ee6b999184aeb8a33633efd1065 100644
>> --- a/lib/s390x/sclp.h
>> +++ b/lib/s390x/sclp.h
>> @@ -129,10 +129,12 @@ struct sclp_facilities {
>>   	uint64_t has_cmma : 1;
>>   	uint64_t has_64bscao : 1;
>>   	uint64_t has_esca : 1;
>> +	uint64_t has_astfleie1 : 1;
>>   	uint64_t has_kss : 1;
>>   	uint64_t has_pfmfi : 1;
>>   	uint64_t has_ibs : 1;
>> -	uint64_t : 64 - 15;
>> +	uint64_t has_astfleie2 : 1;
>> +	uint64_t : 64 - 19;
>>   };
>
> 64 - 17?

Absolutely

> I was wondering why the static assert didn't trigger here. Turns out I 
> only added it to a feature branch that didn't go upstream yet...
>
> Could you do me a favor and add a patch that introduces the static assert:
> _Static_assert(sizeof(struct sclp_facilities) == sizeof(uint64_t));

Sure thing, I can add that to the next version. If we want to keep the padding.

> Then again, why do we pad that at all, it's not a FW struct and I hope 
> that we never cast it to u64 and copy it somewhere.

I would assume nobody ever questioned that since you introduced the struct with
6dff7c9a123c ("s390x: SCLP feature checking")

As the ordering of these bits is nothing like anything anywhere else I agree
that the manual padding is not necessary at all.
So I would rather opt to just remove the padding within its own commit and not
add the assertion.

>>   
>>   /* bit number within a certain byte */
>> @@ -143,8 +145,10 @@ struct sclp_facilities {
>>   #define SCLP_FEAT_116_BIT_64BSCAO	0
>>   #define SCLP_FEAT_116_BIT_CMMA		1
>>   #define SCLP_FEAT_116_BIT_ESCA		4
>> +#define SCLP_FEAT_116_BIT_ASTFLEIE1	7
>>   #define SCLP_FEAT_117_BIT_PFMFI		1
>>   #define SCLP_FEAT_117_BIT_IBS		2
>> +#define SCLP_FEAT_139_BIT_ASTFLEIE2	1
>>   
>>   typedef struct ReadInfo {
>>   	SCCBHeader h;
>>