KVM: s390: implement instruction execution protection for emulated

ifetch

While currently only used to fetch the original instruction on failure
for getting the instruction length code, we should make the page table
walking code future proof.
Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/include/asm/ctl_reg.h

@@ -59,7 +59,9 @@ union ctlreg0 {
 		unsigned long lap  : 1; /* Low-address-protection control */
 		unsigned long	   : 4;
 		unsigned long edat : 1; /* Enhanced-DAT-enablement control */
-		unsigned long	   : 4;
+		unsigned long	   : 2;
+		unsigned long iep  : 1; /* Instruction-Execution-Protection */
+		unsigned long	   : 1;
 		unsigned long afp  : 1; /* AFP-register control */
 		unsigned long vx   : 1; /* Vector enablement control */
 		unsigned long	   : 7;

arch/s390/kvm/gaccess.c

@@ -89,7 +89,7 @@ struct region3_table_entry_fc1 {
 	unsigned long f  : 1; /* Fetch-Protection Bit */
 	unsigned long fc : 1; /* Format-Control */
 	unsigned long p  : 1; /* DAT-Protection Bit */
-	unsigned long co : 1; /* Change-Recording Override */
+	unsigned long iep: 1; /* Instruction-Execution-Protection */
 	unsigned long	 : 2;
 	unsigned long i  : 1; /* Region-Invalid Bit */
 	unsigned long cr : 1; /* Common-Region Bit */
@@ -131,7 +131,7 @@ struct segment_entry_fc1 {
 	unsigned long f  : 1; /* Fetch-Protection Bit */
 	unsigned long fc : 1; /* Format-Control */
 	unsigned long p  : 1; /* DAT-Protection Bit */
-	unsigned long co : 1; /* Change-Recording Override */
+	unsigned long iep: 1; /* Instruction-Execution-Protection */
 	unsigned long	 : 2;
 	unsigned long i  : 1; /* Segment-Invalid Bit */
 	unsigned long cs : 1; /* Common-Segment Bit */
@@ -168,7 +168,8 @@ union page_table_entry {
 		unsigned long z  : 1; /* Zero Bit */
 		unsigned long i  : 1; /* Page-Invalid Bit */
 		unsigned long p  : 1; /* DAT-Protection Bit */
-		unsigned long	 : 9;
+		unsigned long iep: 1; /* Instruction-Execution-Protection */
+		unsigned long	 : 8;
 	};
 };
 
@@ -485,6 +486,7 @@ enum prot_type {
 	PROT_TYPE_KEYC = 1,
 	PROT_TYPE_ALC  = 2,
 	PROT_TYPE_DAT  = 3,
+	PROT_TYPE_IEP  = 4,
 };
 
 static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva,
@@ -500,6 +502,9 @@ static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva,
 	switch (code) {
 	case PGM_PROTECTION:
 		switch (prot) {
+		case PROT_TYPE_IEP:
+			tec->b61 = 1;
+			/* FALL THROUGH */
 		case PROT_TYPE_LA:
 			tec->b56 = 1;
 			break;
@@ -591,6 +596,7 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
  * @gpa: points to where guest physical (absolute) address should be stored
  * @asce: effective asce
  * @mode: indicates the access mode to be used
+ * @prot: returns the type for protection exceptions
  *
  * Translate a guest virtual address into a guest absolute address by means
  * of dynamic address translation as specified by the architecture.
@@ -606,19 +612,21 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
  */
 static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
 				     unsigned long *gpa, const union asce asce,
-				     enum gacc_mode mode)
+				     enum gacc_mode mode, enum prot_type *prot)
 {
 	union vaddress vaddr = {.addr = gva};
 	union raddress raddr = {.addr = gva};
 	union page_table_entry pte;
 	int dat_protection = 0;
+	int iep_protection = 0;
 	union ctlreg0 ctlreg0;
 	unsigned long ptr;
-	int edat1, edat2;
+	int edat1, edat2, iep;
 
 	ctlreg0.val = vcpu->arch.sie_block->gcr[0];
 	edat1 = ctlreg0.edat && test_kvm_facility(vcpu->kvm, 8);
 	edat2 = edat1 && test_kvm_facility(vcpu->kvm, 78);
+	iep = ctlreg0.iep && test_kvm_facility(vcpu->kvm, 130);
 	if (asce.r)
 		goto real_address;
 	ptr = asce.origin * 4096;
@@ -702,6 +710,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
 			return PGM_TRANSLATION_SPEC;
 		if (rtte.fc && edat2) {
 			dat_protection |= rtte.fc1.p;
+			iep_protection = rtte.fc1.iep;
 			raddr.rfaa = rtte.fc1.rfaa;
 			goto absolute_address;
 		}
@@ -729,6 +738,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
 			return PGM_TRANSLATION_SPEC;
 		if (ste.fc && edat1) {
 			dat_protection |= ste.fc1.p;
+			iep_protection = ste.fc1.iep;
 			raddr.sfaa = ste.fc1.sfaa;
 			goto absolute_address;
 		}
@@ -745,12 +755,19 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
 	if (pte.z)
 		return PGM_TRANSLATION_SPEC;
 	dat_protection |= pte.p;
+	iep_protection = pte.iep;
 	raddr.pfra = pte.pfra;
 real_address:
 	raddr.addr = kvm_s390_real_to_abs(vcpu, raddr.addr);
 absolute_address:
-	if (mode == GACC_STORE && dat_protection)
+	if (mode == GACC_STORE && dat_protection) {
+		*prot = PROT_TYPE_DAT;
 		return PGM_PROTECTION;
+	}
+	if (mode == GACC_IFETCH && iep_protection && iep) {
+		*prot = PROT_TYPE_IEP;
+		return PGM_PROTECTION;
+	}
 	if (kvm_is_error_gpa(vcpu->kvm, raddr.addr))
 		return PGM_ADDRESSING;
 	*gpa = raddr.addr;
@@ -782,6 +799,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
 {
 	psw_t *psw = &vcpu->arch.sie_block->gpsw;
 	int lap_enabled, rc = 0;
+	enum prot_type prot;
 
 	lap_enabled = low_address_protection_enabled(vcpu, asce);
 	while (nr_pages) {
@@ -791,7 +809,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
 					 PROT_TYPE_LA);
 		ga &= PAGE_MASK;
 		if (psw_bits(*psw).t) {
-			rc = guest_translate(vcpu, ga, pages, asce, mode);
+			rc = guest_translate(vcpu, ga, pages, asce, mode, &prot);
 			if (rc < 0)
 				return rc;
 		} else {
@@ -800,7 +818,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
 				rc = PGM_ADDRESSING;
 		}
 		if (rc)
-			return trans_exc(vcpu, rc, ga, ar, mode, PROT_TYPE_DAT);
+			return trans_exc(vcpu, rc, ga, ar, mode, prot);
 		ga += PAGE_SIZE;
 		pages++;
 		nr_pages--;
@@ -886,6 +904,7 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
 			    unsigned long *gpa, enum gacc_mode mode)
 {
 	psw_t *psw = &vcpu->arch.sie_block->gpsw;
+	enum prot_type prot;
 	union asce asce;
 	int rc;
 
@@ -900,9 +919,9 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
 	}
 
 	if (psw_bits(*psw).t && !asce.r) {	/* Use DAT? */
-		rc = guest_translate(vcpu, gva, gpa, asce, mode);
+		rc = guest_translate(vcpu, gva, gpa, asce, mode, &prot);
 		if (rc > 0)
-			return trans_exc(vcpu, rc, gva, 0, mode, PROT_TYPE_DAT);
+			return trans_exc(vcpu, rc, gva, 0, mode, prot);
 	} else {
 		*gpa = kvm_s390_real_to_abs(vcpu, gva);
 		if (kvm_is_error_gpa(vcpu->kvm, *gpa))