s390/ap,zcrypt,vfio: introduce and use ap_queue_status_reg union

Introduce a new ap queue status register wrapper union to access register
wide values. So the inline assembler only sees register wide values but the
surrounding code may use a more structured view of the same value and a
reader of the code (and the compiler) gets a clear understanding about the
mapping between fields and register values.

All the changes to access the ap queue status are local to the inline
functions within ap.h. However, the struct ap_qirq_ctrl has been replaces
by a union for same reason and this needed slight adaptions in the calling
code.
Suggested-by: Halil Pasic <pasic@linux.ibm.com>
Suggested-by: Andreas Arnez <arnez@linux.ibm.com>
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/include/asm/ap.h

@@ -49,6 +49,19 @@ struct ap_queue_status {
 	unsigned int _pad2		: 16;
 };
 
+/*
+ * AP queue status reg union to access the reg1
+ * register with the lower 32 bits comprising the
+ * ap queue status.
+ */
+union ap_queue_status_reg {
+	unsigned long value;
+	struct {
+		u32 _pad;
+		struct ap_queue_status status;
+	};
+};
+
 /**
  * ap_intructions_available() - Test if AP instructions are available.
  *
@@ -82,7 +95,7 @@ static inline bool ap_instructions_available(void)
  */
 static inline struct ap_queue_status ap_tapq(ap_qid_t qid, unsigned long *info)
 {
-	struct ap_queue_status reg1;
+	union ap_queue_status_reg reg1;
 	unsigned long reg2;
 
 	asm volatile(
@@ -91,12 +104,12 @@ static inline struct ap_queue_status ap_tapq(ap_qid_t qid, unsigned long *info)
 		"	.insn	rre,0xb2af0000,0,0\n"	/* PQAP(TAPQ) */
 		"	lgr	%[reg1],1\n"		/* gr1 (status) into reg1 */
 		"	lgr	%[reg2],2\n"		/* gr2 into reg2 */
-		: [reg1] "=&d" (reg1), [reg2] "=&d" (reg2)
+		: [reg1] "=&d" (reg1.value), [reg2] "=&d" (reg2)
 		: [qid] "d" (qid)
 		: "cc", "0", "1", "2");
 	if (info)
 		*info = reg2;
-	return reg1;
+	return reg1.status;
 }
 
 /**
@@ -125,16 +138,16 @@ static inline struct ap_queue_status ap_test_queue(ap_qid_t qid,
 static inline struct ap_queue_status ap_rapq(ap_qid_t qid)
 {
 	unsigned long reg0 = qid | (1UL << 24);  /* fc 1UL is RAPQ */
-	struct ap_queue_status reg1;
+	union ap_queue_status_reg reg1;
 
 	asm volatile(
 		"	lgr	0,%[reg0]\n"		/* qid arg into gr0 */
 		"	.insn	rre,0xb2af0000,0,0\n"	/* PQAP(RAPQ) */
 		"	lgr	%[reg1],1\n"		/* gr1 (status) into reg1 */
-		: [reg1] "=&d" (reg1)
+		: [reg1] "=&d" (reg1.value)
 		: [reg0] "d" (reg0)
 		: "cc", "0", "1");
-	return reg1;
+	return reg1.status;
 }
 
 /**
@@ -146,16 +159,16 @@ static inline struct ap_queue_status ap_rapq(ap_qid_t qid)
 static inline struct ap_queue_status ap_zapq(ap_qid_t qid)
 {
 	unsigned long reg0 = qid | (2UL << 24);  /* fc 2UL is ZAPQ */
-	struct ap_queue_status reg1;
+	union ap_queue_status_reg reg1;
 
 	asm volatile(
 		"	lgr	0,%[reg0]\n"		/* qid arg into gr0 */
 		"	.insn	rre,0xb2af0000,0,0\n"	/* PQAP(ZAPQ) */
 		"	lgr	%[reg1],1\n"		/* gr1 (status) into reg1 */
-		: [reg1] "=&d" (reg1)
+		: [reg1] "=&d" (reg1.value)
 		: [reg0] "d" (reg0)
 		: "cc", "0", "1");
-	return reg1;
+	return reg1.status;
 }
 
 /**
@@ -209,18 +222,21 @@ static inline int ap_qci(struct ap_config_info *config)
  * parameter to the PQAP(AQIC) instruction. For details please
  * see the AR documentation.
  */
-struct ap_qirq_ctrl {
-	unsigned int _res1 : 8;
+union ap_qirq_ctrl {
+	unsigned long value;
+	struct {
+		unsigned int	   : 8;
 		unsigned int zone  : 8;	/* zone info */
 		unsigned int ir	   : 1;	/* ir flag: enable (1) or disable (0) irq */
-	unsigned int _res2 : 4;
+		unsigned int	   : 4;
 		unsigned int gisc  : 3;	/* guest isc field */
-	unsigned int _res3 : 6;
+		unsigned int	   : 6;
 		unsigned int gf	   : 2;	/* gisa format */
-	unsigned int _res4 : 1;
+		unsigned int	   : 1;
 		unsigned int gisa  : 27;	/* gisa origin */
-	unsigned int _res5 : 1;
+		unsigned int	   : 1;
 		unsigned int isc   : 3;	/* irq sub class */
+	};
 };
 
 /**
@@ -232,21 +248,14 @@ struct ap_qirq_ctrl {
  * Returns AP queue status.
  */
 static inline struct ap_queue_status ap_aqic(ap_qid_t qid,
-					     struct ap_qirq_ctrl qirqctrl,
+					     union ap_qirq_ctrl qirqctrl,
 					     phys_addr_t pa_ind)
 {
 	unsigned long reg0 = qid | (3UL << 24);  /* fc 3UL is AQIC */
-	union {
-		unsigned long value;
-		struct ap_qirq_ctrl qirqctrl;
-		struct {
-			u32 _pad;
-			struct ap_queue_status status;
-		};
-	} reg1;
+	union ap_queue_status_reg reg1;
 	unsigned long reg2 = pa_ind;
 
-	reg1.qirqctrl = qirqctrl;
+	reg1.value = qirqctrl.value;
 
 	asm volatile(
 		"	lgr	0,%[reg0]\n"		/* qid param into gr0 */
@@ -254,7 +263,7 @@ static inline struct ap_queue_status ap_aqic(ap_qid_t qid,
 		"	lgr	2,%[reg2]\n"		/* ni addr into gr2 */
 		"	.insn	rre,0xb2af0000,0,0\n"	/* PQAP(AQIC) */
 		"	lgr	%[reg1],1\n"		/* gr1 (status) into reg1 */
-		: [reg1] "+&d" (reg1)
+		: [reg1] "+&d" (reg1.value)
 		: [reg0] "d" (reg0), [reg2] "d" (reg2)
 		: "cc", "memory", "0", "1", "2");
 
@@ -291,13 +300,7 @@ static inline struct ap_queue_status ap_qact(ap_qid_t qid, int ifbit,
 					     union ap_qact_ap_info *apinfo)
 {
 	unsigned long reg0 = qid | (5UL << 24) | ((ifbit & 0x01) << 22);
-	union {
-		unsigned long value;
-		struct {
-			u32 _pad;
-			struct ap_queue_status status;
-		};
-	} reg1;
+	union ap_queue_status_reg reg1;
 	unsigned long reg2;
 
 	reg1.value = apinfo->val;
@@ -308,7 +311,7 @@ static inline struct ap_queue_status ap_qact(ap_qid_t qid, int ifbit,
 		"	.insn	rre,0xb2af0000,0,0\n"	/* PQAP(QACT) */
 		"	lgr	%[reg1],1\n"		/* gr1 (status) into reg1 */
 		"	lgr	%[reg2],2\n"		/* qact out info into reg2 */
-		: [reg1] "+&d" (reg1), [reg2] "=&d" (reg2)
+		: [reg1] "+&d" (reg1.value), [reg2] "=&d" (reg2)
 		: [reg0] "d" (reg0)
 		: "cc", "0", "1", "2");
 	apinfo->val = reg2;
@@ -333,7 +336,7 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
 {
 	unsigned long reg0 = qid | 0x40000000UL;  /* 0x4... is last msg part */
 	union register_pair nqap_r1, nqap_r2;
-	struct ap_queue_status reg1;
+	union ap_queue_status_reg reg1;
 
 	nqap_r1.even = (unsigned int)(psmid >> 32);
 	nqap_r1.odd  = psmid & 0xffffffff;
@@ -345,11 +348,11 @@ static inline struct ap_queue_status ap_nqap(ap_qid_t qid,
 		"0:	.insn	rre,0xb2ad0000,%[nqap_r1],%[nqap_r2]\n"
 		"	brc	2,0b\n"       /* handle partial completion */
 		"	lgr	%[reg1],1\n"  /* gr1 (status) into reg1 */
-		: [reg0] "+&d" (reg0), [reg1] "=&d" (reg1),
+		: [reg0] "+&d" (reg0), [reg1] "=&d" (reg1.value),
 		  [nqap_r2] "+&d" (nqap_r2.pair)
 		: [nqap_r1] "d" (nqap_r1.pair)
 		: "cc", "memory", "0", "1");
-	return reg1;
+	return reg1.status;
 }
 
 /**
@@ -389,7 +392,7 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
 					     unsigned long *resgr0)
 {
 	unsigned long reg0 = resgr0 && *resgr0 ? *resgr0 : qid | 0x80000000UL;
-	struct ap_queue_status reg1;
+	union ap_queue_status_reg reg1;
 	unsigned long reg2;
 	union register_pair rp1, rp2;
 
@@ -408,8 +411,9 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
 		"2:	lgr	%[reg0],0\n"   /* gr0 (qid + info) into reg0 */
 		"	lgr	%[reg1],1\n"   /* gr1 (status) into reg1 */
 		"	lgr	%[reg2],2\n"   /* gr2 (res length) into reg2 */
-		: [reg0] "+&d" (reg0), [reg1] "=&d" (reg1), [reg2] "=&d" (reg2),
-		  [rp1] "+&d" (rp1.pair), [rp2] "+&d" (rp2.pair)
+		: [reg0] "+&d" (reg0), [reg1] "=&d" (reg1.value),
+		  [reg2] "=&d" (reg2), [rp1] "+&d" (rp1.pair),
+		  [rp2] "+&d" (rp2.pair)
 		:
 		: "cc", "memory", "0", "1", "2");
 
@@ -421,7 +425,7 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
 		 * Signal the caller that this dqap is only partially received
 		 * with a special status response code 0xFF and *resgr0 updated
 		 */
-		reg1.response_code = 0xFF;
+		reg1.status.response_code = 0xFF;
 		if (resgr0)
 			*resgr0 = reg0;
 	} else {
@@ -430,7 +434,7 @@ static inline struct ap_queue_status ap_dqap(ap_qid_t qid,
 			*resgr0 = 0;
 	}
 
-	return reg1;
+	return reg1.status;
 }
 
 /*

drivers/s390/crypto/ap_queue.c

@@ -29,8 +29,8 @@ static void __ap_flush_queue(struct ap_queue *aq);
  */
 static int ap_queue_enable_irq(struct ap_queue *aq, void *ind)
 {
+	union ap_qirq_ctrl qirqctrl = { .value = 0 };
 	struct ap_queue_status status;
-	struct ap_qirq_ctrl qirqctrl = { 0 };
 
 	qirqctrl.ir = 1;
 	qirqctrl.isc = AP_ISC;

drivers/s390/crypto/vfio_ap_ops.c

@@ -301,7 +301,7 @@ static void vfio_ap_free_aqic_resources(struct vfio_ap_queue *q)
  */
 static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
 {
-	struct ap_qirq_ctrl aqic_gisa = {};
+	union ap_qirq_ctrl aqic_gisa = { .value = 0 };
 	struct ap_queue_status status;
 	int retries = 5;
 
@@ -384,7 +384,7 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
 						 int isc,
 						 struct kvm_vcpu *vcpu)
 {
-	struct ap_qirq_ctrl aqic_gisa = {};
+	union ap_qirq_ctrl aqic_gisa = { .value = 0 };
 	struct ap_queue_status status = {};
 	struct kvm_s390_gisa *gisa;
 	struct page *h_page;