KVM: s390: Add access register mode

Access register mode is one of the modes that control dynamic address
translation. In this mode the address space is specified by values of
the access registers. The effective address-space-control element is
obtained from the result of the access register translation. See
the "Access-Register Introduction" section of the chapter 5 "Program
Execution" in "Principles of Operations" for more details.

Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/gaccess.c

@@ -10,6 +10,7 @@
 #include <asm/pgtable.h>
 #include "kvm-s390.h"
 #include "gaccess.h"
+#include <asm/switch_to.h>
 
 union asce {
 	unsigned long val;
@@ -207,6 +208,54 @@ union raddress {
 	unsigned long pfra : 52; /* Page-Frame Real Address */
 };
 
+union alet {
+	u32 val;
+	struct {
+		u32 reserved : 7;
+		u32 p        : 1;
+		u32 alesn    : 8;
+		u32 alen     : 16;
+	};
+};
+
+union ald {
+	u32 val;
+	struct {
+		u32     : 1;
+		u32 alo : 24;
+		u32 all : 7;
+	};
+};
+
+struct ale {
+	unsigned long i      : 1; /* ALEN-Invalid Bit */
+	unsigned long        : 5;
+	unsigned long fo     : 1; /* Fetch-Only Bit */
+	unsigned long p      : 1; /* Private Bit */
+	unsigned long alesn  : 8; /* Access-List-Entry Sequence Number */
+	unsigned long aleax  : 16; /* Access-List-Entry Authorization Index */
+	unsigned long        : 32;
+	unsigned long        : 1;
+	unsigned long asteo  : 25; /* ASN-Second-Table-Entry Origin */
+	unsigned long        : 6;
+	unsigned long astesn : 32; /* ASTE Sequence Number */
+} __packed;
+
+struct aste {
+	unsigned long i      : 1; /* ASX-Invalid Bit */
+	unsigned long ato    : 29; /* Authority-Table Origin */
+	unsigned long        : 1;
+	unsigned long b      : 1; /* Base-Space Bit */
+	unsigned long ax     : 16; /* Authorization Index */
+	unsigned long atl    : 12; /* Authority-Table Length */
+	unsigned long        : 2;
+	unsigned long ca     : 1; /* Controlled-ASN Bit */
+	unsigned long ra     : 1; /* Reusable-ASN Bit */
+	unsigned long asce   : 64; /* Address-Space-Control Element */
+	unsigned long ald    : 32;
+	unsigned long astesn : 32;
+	/* .. more fields there */
+} __packed;
 
 int ipte_lock_held(struct kvm_vcpu *vcpu)
 {
@@ -307,15 +356,157 @@ void ipte_unlock(struct kvm_vcpu *vcpu)
 		ipte_unlock_simple(vcpu);
 }
 
-static unsigned long get_vcpu_asce(struct kvm_vcpu *vcpu)
+static int ar_translation(struct kvm_vcpu *vcpu, union asce *asce, ar_t ar,
+			  int write)
+{
+	union alet alet;
+	struct ale ale;
+	struct aste aste;
+	unsigned long ald_addr, authority_table_addr;
+	union ald ald;
+	int eax, rc;
+	u8 authority_table;
+
+	if (ar >= NUM_ACRS)
+		return -EINVAL;
+
+	save_access_regs(vcpu->run->s.regs.acrs);
+	alet.val = vcpu->run->s.regs.acrs[ar];
+
+	if (ar == 0 || alet.val == 0) {
+		asce->val = vcpu->arch.sie_block->gcr[1];
+		return 0;
+	} else if (alet.val == 1) {
+		asce->val = vcpu->arch.sie_block->gcr[7];
+		return 0;
+	}
+
+	if (alet.reserved)
+		return PGM_ALET_SPECIFICATION;
+
+	if (alet.p)
+		ald_addr = vcpu->arch.sie_block->gcr[5];
+	else
+		ald_addr = vcpu->arch.sie_block->gcr[2];
+	ald_addr &= 0x7fffffc0;
+
+	rc = read_guest_real(vcpu, ald_addr + 16, &ald.val, sizeof(union ald));
+	if (rc)
+		return rc;
+
+	if (alet.alen / 8 > ald.all)
+		return PGM_ALEN_TRANSLATION;
+
+	if (0x7fffffff - ald.alo * 128 < alet.alen * 16)
+		return PGM_ADDRESSING;
+
+	rc = read_guest_real(vcpu, ald.alo * 128 + alet.alen * 16, &ale,
+			     sizeof(struct ale));
+	if (rc)
+		return rc;
+
+	if (ale.i == 1)
+		return PGM_ALEN_TRANSLATION;
+	if (ale.alesn != alet.alesn)
+		return PGM_ALE_SEQUENCE;
+
+	rc = read_guest_real(vcpu, ale.asteo * 64, &aste, sizeof(struct aste));
+	if (rc)
+		return rc;
+
+	if (aste.i)
+		return PGM_ASTE_VALIDITY;
+	if (aste.astesn != ale.astesn)
+		return PGM_ASTE_SEQUENCE;
+
+	if (ale.p == 1) {
+		eax = (vcpu->arch.sie_block->gcr[8] >> 16) & 0xffff;
+		if (ale.aleax != eax) {
+			if (eax / 16 > aste.atl)
+				return PGM_EXTENDED_AUTHORITY;
+
+			authority_table_addr = aste.ato * 4 + eax / 4;
+
+			rc = read_guest_real(vcpu, authority_table_addr,
+					     &authority_table,
+					     sizeof(u8));
+			if (rc)
+				return rc;
+
+			if ((authority_table & (0x40 >> ((eax & 3) * 2))) == 0)
+				return PGM_EXTENDED_AUTHORITY;
+		}
+	}
+
+	if (ale.fo == 1 && write)
+		return PGM_PROTECTION;
+
+	asce->val = aste.asce;
+	return 0;
+}
+
+struct trans_exc_code_bits {
+	unsigned long addr : 52; /* Translation-exception Address */
+	unsigned long fsi  : 2;  /* Access Exception Fetch/Store Indication */
+	unsigned long	   : 6;
+	unsigned long b60  : 1;
+	unsigned long b61  : 1;
+	unsigned long as   : 2;  /* ASCE Identifier */
+};
+
+enum {
+	FSI_UNKNOWN = 0, /* Unknown wether fetch or store */
+	FSI_STORE   = 1, /* Exception was due to store operation */
+	FSI_FETCH   = 2  /* Exception was due to fetch operation */
+};
+
+static int get_vcpu_asce(struct kvm_vcpu *vcpu, union asce *asce,
+			 ar_t ar, int write)
 {
+	int rc;
+	psw_t *psw = &vcpu->arch.sie_block->gpsw;
+	struct kvm_s390_pgm_info *pgm = &vcpu->arch.pgm;
+	struct trans_exc_code_bits *tec_bits;
+
+	memset(pgm, 0, sizeof(*pgm));
+	tec_bits = (struct trans_exc_code_bits *)&pgm->trans_exc_code;
+	tec_bits->fsi = write ? FSI_STORE : FSI_FETCH;
+	tec_bits->as = psw_bits(*psw).as;
+
+	if (!psw_bits(*psw).t) {
+		asce->val = 0;
+		asce->r = 1;
+		return 0;
+	}
+
 	switch (psw_bits(vcpu->arch.sie_block->gpsw).as) {
 	case PSW_AS_PRIMARY:
-		return vcpu->arch.sie_block->gcr[1];
+		asce->val = vcpu->arch.sie_block->gcr[1];
+		return 0;
 	case PSW_AS_SECONDARY:
-		return vcpu->arch.sie_block->gcr[7];
+		asce->val = vcpu->arch.sie_block->gcr[7];
+		return 0;
 	case PSW_AS_HOME:
-		return vcpu->arch.sie_block->gcr[13];
+		asce->val = vcpu->arch.sie_block->gcr[13];
+		return 0;
+	case PSW_AS_ACCREG:
+		rc = ar_translation(vcpu, asce, ar, write);
+		switch (rc) {
+		case PGM_ALEN_TRANSLATION:
+		case PGM_ALE_SEQUENCE:
+		case PGM_ASTE_VALIDITY:
+		case PGM_ASTE_SEQUENCE:
+		case PGM_EXTENDED_AUTHORITY:
+			vcpu->arch.pgm.exc_access_id = ar;
+			break;
+		case PGM_PROTECTION:
+			tec_bits->b60 = 1;
+			tec_bits->b61 = 1;
+			break;
+		}
+		if (rc > 0)
+			pgm->code = rc;
+		return rc;
 	}
 	return 0;
 }
@@ -519,20 +710,6 @@ static int low_address_protection_enabled(struct kvm_vcpu *vcpu,
 	return 1;
 }
 
-struct trans_exc_code_bits {
-	unsigned long addr : 52; /* Translation-exception Address */
-	unsigned long fsi  : 2;  /* Access Exception Fetch/Store Indication */
-	unsigned long	   : 7;
-	unsigned long b61  : 1;
-	unsigned long as   : 2;  /* ASCE Identifier */
-};
-
-enum {
-	FSI_UNKNOWN = 0, /* Unknown wether fetch or store */
-	FSI_STORE   = 1, /* Exception was due to store operation */
-	FSI_FETCH   = 2  /* Exception was due to fetch operation */
-};
-
 static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga,
 			    unsigned long *pages, unsigned long nr_pages,
 			    const union asce asce, int write)
@@ -542,10 +719,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga,
 	struct trans_exc_code_bits *tec_bits;
 	int lap_enabled, rc;
 
-	memset(pgm, 0, sizeof(*pgm));
 	tec_bits = (struct trans_exc_code_bits *)&pgm->trans_exc_code;
-	tec_bits->fsi = write ? FSI_STORE : FSI_FETCH;
-	tec_bits->as = psw_bits(*psw).as;
 	lap_enabled = low_address_protection_enabled(vcpu, asce);
 	while (nr_pages) {
 		ga = kvm_s390_logical_to_effective(vcpu, ga);
@@ -590,16 +764,15 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, ar_t ar, void *data,
 
 	if (!len)
 		return 0;
-	/* Access register mode is not supported yet. */
-	if (psw_bits(*psw).t && psw_bits(*psw).as == PSW_AS_ACCREG)
-		return -EOPNOTSUPP;
+	rc = get_vcpu_asce(vcpu, &asce, ar, write);
+	if (rc)
+		return rc;
 	nr_pages = (((ga & ~PAGE_MASK) + len - 1) >> PAGE_SHIFT) + 1;
 	pages = pages_array;
 	if (nr_pages > ARRAY_SIZE(pages_array))
 		pages = vmalloc(nr_pages * sizeof(unsigned long));
 	if (!pages)
 		return -ENOMEM;
-	asce.val = get_vcpu_asce(vcpu);
 	need_ipte_lock = psw_bits(*psw).t && !asce.r;
 	if (need_ipte_lock)
 		ipte_lock(vcpu);
@@ -660,17 +833,12 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, ar_t ar,
 	union asce asce;
 	int rc;
 
-	/* Access register mode is not supported yet. */
-	if (psw_bits(*psw).t && psw_bits(*psw).as == PSW_AS_ACCREG)
-		return -EOPNOTSUPP;
-
 	gva = kvm_s390_logical_to_effective(vcpu, gva);
-	memset(pgm, 0, sizeof(*pgm));
 	tec = (struct trans_exc_code_bits *)&pgm->trans_exc_code;
-	tec->as = psw_bits(*psw).as;
-	tec->fsi = write ? FSI_STORE : FSI_FETCH;
+	rc = get_vcpu_asce(vcpu, &asce, ar, write);
 	tec->addr = gva >> PAGE_SHIFT;
-	asce.val = get_vcpu_asce(vcpu);
+	if (rc)
+		return rc;
 	if (is_low_address(gva) && low_address_protection_enabled(vcpu, asce)) {
 		if (write) {
 			rc = pgm->code = PGM_PROTECTION;

arch/s390/kvm/gaccess.h

@@ -177,8 +177,7 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
  * If DAT is off data will be copied to guest real or absolute memory.
  * If DAT is on data will be copied to the address space as specified by
  * the address space bits of the PSW:
- * Primary, secondory or home space (access register mode is currently not
- * implemented).
+ * Primary, secondary, home space or access register mode.
  * The addressing mode of the PSW is also inspected, so that address wrap
  * around is taken into account for 24-, 31- and 64-bit addressing mode,
  * if the to be copied data crosses page boundaries in guest address space.