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1 /*
2  * handling diagnose instructions
3  *
4  * Copyright IBM Corp. 2008, 2011
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License (version 2 only)
8  * as published by the Free Software Foundation.
9  *
10  *    Author(s): Carsten Otte <cotte@de.ibm.com>
11  *               Christian Borntraeger <borntraeger@de.ibm.com>
12  */
13 
14 #include <linux/kvm.h>
15 #include <linux/kvm_host.h>
16 #include <asm/pgalloc.h>
17 #include <asm/virtio-ccw.h>
18 #include "kvm-s390.h"
19 #include "trace.h"
20 #include "trace-s390.h"
21 #include "gaccess.h"
22 
diag_release_pages(struct kvm_vcpu * vcpu)23 static int diag_release_pages(struct kvm_vcpu *vcpu)
24 {
25 	unsigned long start, end;
26 	unsigned long prefix  = kvm_s390_get_prefix(vcpu);
27 
28 	start = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
29 	end = vcpu->run->s.regs.gprs[vcpu->arch.sie_block->ipa & 0xf] + 4096;
30 	vcpu->stat.diagnose_10++;
31 
32 	if (start & ~PAGE_MASK || end & ~PAGE_MASK || start >= end
33 	    || start < 2 * PAGE_SIZE)
34 		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
35 
36 	VCPU_EVENT(vcpu, 5, "diag release pages %lX %lX", start, end);
37 
38 	/*
39 	 * We checked for start >= end above, so lets check for the
40 	 * fast path (no prefix swap page involved)
41 	 */
42 	if (end <= prefix || start >= prefix + 2 * PAGE_SIZE) {
43 		gmap_discard(vcpu->arch.gmap, start, end);
44 	} else {
45 		/*
46 		 * This is slow path.  gmap_discard will check for start
47 		 * so lets split this into before prefix, prefix, after
48 		 * prefix and let gmap_discard make some of these calls
49 		 * NOPs.
50 		 */
51 		gmap_discard(vcpu->arch.gmap, start, prefix);
52 		if (start <= prefix)
53 			gmap_discard(vcpu->arch.gmap, 0, 4096);
54 		if (end > prefix + 4096)
55 			gmap_discard(vcpu->arch.gmap, 4096, 8192);
56 		gmap_discard(vcpu->arch.gmap, prefix + 2 * PAGE_SIZE, end);
57 	}
58 	return 0;
59 }
60 
__diag_page_ref_service(struct kvm_vcpu * vcpu)61 static int __diag_page_ref_service(struct kvm_vcpu *vcpu)
62 {
63 	struct prs_parm {
64 		u16 code;
65 		u16 subcode;
66 		u16 parm_len;
67 		u16 parm_version;
68 		u64 token_addr;
69 		u64 select_mask;
70 		u64 compare_mask;
71 		u64 zarch;
72 	};
73 	struct prs_parm parm;
74 	int rc;
75 	u16 rx = (vcpu->arch.sie_block->ipa & 0xf0) >> 4;
76 	u16 ry = (vcpu->arch.sie_block->ipa & 0x0f);
77 
78 	VCPU_EVENT(vcpu, 3, "diag page reference parameter block at 0x%llx",
79 		   vcpu->run->s.regs.gprs[rx]);
80 	vcpu->stat.diagnose_258++;
81 	if (vcpu->run->s.regs.gprs[rx] & 7)
82 		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
83 	rc = read_guest(vcpu, vcpu->run->s.regs.gprs[rx], rx, &parm, sizeof(parm));
84 	if (rc)
85 		return kvm_s390_inject_prog_cond(vcpu, rc);
86 	if (parm.parm_version != 2 || parm.parm_len < 5 || parm.code != 0x258)
87 		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
88 
89 	switch (parm.subcode) {
90 	case 0: /* TOKEN */
91 		VCPU_EVENT(vcpu, 3, "pageref token addr 0x%llx "
92 			   "select mask 0x%llx compare mask 0x%llx",
93 			   parm.token_addr, parm.select_mask, parm.compare_mask);
94 		if (vcpu->arch.pfault_token != KVM_S390_PFAULT_TOKEN_INVALID) {
95 			/*
96 			 * If the pagefault handshake is already activated,
97 			 * the token must not be changed.  We have to return
98 			 * decimal 8 instead, as mandated in SC24-6084.
99 			 */
100 			vcpu->run->s.regs.gprs[ry] = 8;
101 			return 0;
102 		}
103 
104 		if ((parm.compare_mask & parm.select_mask) != parm.compare_mask ||
105 		    parm.token_addr & 7 || parm.zarch != 0x8000000000000000ULL)
106 			return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
107 
108 		if (kvm_is_error_gpa(vcpu->kvm, parm.token_addr))
109 			return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
110 
111 		vcpu->arch.pfault_token = parm.token_addr;
112 		vcpu->arch.pfault_select = parm.select_mask;
113 		vcpu->arch.pfault_compare = parm.compare_mask;
114 		vcpu->run->s.regs.gprs[ry] = 0;
115 		rc = 0;
116 		break;
117 	case 1: /*
118 		 * CANCEL
119 		 * Specification allows to let already pending tokens survive
120 		 * the cancel, therefore to reduce code complexity, we assume
121 		 * all outstanding tokens are already pending.
122 		 */
123 		VCPU_EVENT(vcpu, 3, "pageref cancel addr 0x%llx", parm.token_addr);
124 		if (parm.token_addr || parm.select_mask ||
125 		    parm.compare_mask || parm.zarch)
126 			return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
127 
128 		vcpu->run->s.regs.gprs[ry] = 0;
129 		/*
130 		 * If the pfault handling was not established or is already
131 		 * canceled SC24-6084 requests to return decimal 4.
132 		 */
133 		if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
134 			vcpu->run->s.regs.gprs[ry] = 4;
135 		else
136 			vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
137 
138 		rc = 0;
139 		break;
140 	default:
141 		rc = -EOPNOTSUPP;
142 		break;
143 	}
144 
145 	return rc;
146 }
147 
__diag_time_slice_end(struct kvm_vcpu * vcpu)148 static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
149 {
150 	VCPU_EVENT(vcpu, 5, "%s", "diag time slice end");
151 	vcpu->stat.diagnose_44++;
152 	kvm_vcpu_on_spin(vcpu);
153 	return 0;
154 }
155 
__diag_time_slice_end_directed(struct kvm_vcpu * vcpu)156 static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
157 {
158 	struct kvm *kvm = vcpu->kvm;
159 	struct kvm_vcpu *tcpu;
160 	int tid;
161 	int i;
162 
163 	tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
164 	vcpu->stat.diagnose_9c++;
165 	VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d", tid);
166 
167 	if (tid == vcpu->vcpu_id)
168 		return 0;
169 
170 	kvm_for_each_vcpu(i, tcpu, kvm)
171 		if (tcpu->vcpu_id == tid) {
172 			kvm_vcpu_yield_to(tcpu);
173 			break;
174 		}
175 
176 	return 0;
177 }
178 
__diag_ipl_functions(struct kvm_vcpu * vcpu)179 static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
180 {
181 	unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
182 	unsigned long subcode = vcpu->run->s.regs.gprs[reg] & 0xffff;
183 
184 	VCPU_EVENT(vcpu, 3, "diag ipl functions, subcode %lx", subcode);
185 	vcpu->stat.diagnose_308++;
186 	switch (subcode) {
187 	case 3:
188 		vcpu->run->s390_reset_flags = KVM_S390_RESET_CLEAR;
189 		break;
190 	case 4:
191 		vcpu->run->s390_reset_flags = 0;
192 		break;
193 	default:
194 		return -EOPNOTSUPP;
195 	}
196 
197 	if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
198 		kvm_s390_vcpu_stop(vcpu);
199 	vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
200 	vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
201 	vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
202 	vcpu->run->exit_reason = KVM_EXIT_S390_RESET;
203 	VCPU_EVENT(vcpu, 3, "requesting userspace resets %llx",
204 	  vcpu->run->s390_reset_flags);
205 	trace_kvm_s390_request_resets(vcpu->run->s390_reset_flags);
206 	return -EREMOTE;
207 }
208 
__diag_virtio_hypercall(struct kvm_vcpu * vcpu)209 static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
210 {
211 	int ret;
212 
213 	vcpu->stat.diagnose_500++;
214 	/* No virtio-ccw notification? Get out quickly. */
215 	if (!vcpu->kvm->arch.css_support ||
216 	    (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
217 		return -EOPNOTSUPP;
218 
219 	/*
220 	 * The layout is as follows:
221 	 * - gpr 2 contains the subchannel id (passed as addr)
222 	 * - gpr 3 contains the virtqueue index (passed as datamatch)
223 	 * - gpr 4 contains the index on the bus (optionally)
224 	 */
225 	ret = kvm_io_bus_write_cookie(vcpu, KVM_VIRTIO_CCW_NOTIFY_BUS,
226 				      vcpu->run->s.regs.gprs[2] & 0xffffffff,
227 				      8, &vcpu->run->s.regs.gprs[3],
228 				      vcpu->run->s.regs.gprs[4]);
229 
230 	/*
231 	 * Return cookie in gpr 2, but don't overwrite the register if the
232 	 * diagnose will be handled by userspace.
233 	 */
234 	if (ret != -EOPNOTSUPP)
235 		vcpu->run->s.regs.gprs[2] = ret;
236 	/* kvm_io_bus_write_cookie returns -EOPNOTSUPP if it found no match. */
237 	return ret < 0 ? ret : 0;
238 }
239 
kvm_s390_handle_diag(struct kvm_vcpu * vcpu)240 int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
241 {
242 	int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff;
243 
244 	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
245 		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
246 
247 	trace_kvm_s390_handle_diag(vcpu, code);
248 	switch (code) {
249 	case 0x10:
250 		return diag_release_pages(vcpu);
251 	case 0x44:
252 		return __diag_time_slice_end(vcpu);
253 	case 0x9c:
254 		return __diag_time_slice_end_directed(vcpu);
255 	case 0x258:
256 		return __diag_page_ref_service(vcpu);
257 	case 0x308:
258 		return __diag_ipl_functions(vcpu);
259 	case 0x500:
260 		return __diag_virtio_hypercall(vcpu);
261 	default:
262 		return -EOPNOTSUPP;
263 	}
264 }
265