1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * handling diagnose instructions
4 *
5 * Copyright IBM Corp. 2008, 2020
6 *
7 * Author(s): Carsten Otte <cotte@de.ibm.com>
8 * Christian Borntraeger <borntraeger@de.ibm.com>
9 */
10
11 #include <linux/kvm.h>
12 #include <linux/kvm_host.h>
13 #include <asm/gmap.h>
14 #include <asm/virtio-ccw.h>
15 #include "kvm-s390.h"
16 #include "trace.h"
17 #include "trace-s390.h"
18 #include "gaccess.h"
19
diag_release_pages(struct kvm_vcpu * vcpu)20 static int diag_release_pages(struct kvm_vcpu *vcpu)
21 {
22 unsigned long start, end;
23 unsigned long prefix = kvm_s390_get_prefix(vcpu);
24
25 start = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
26 end = vcpu->run->s.regs.gprs[vcpu->arch.sie_block->ipa & 0xf] + PAGE_SIZE;
27 vcpu->stat.instruction_diagnose_10++;
28
29 if (start & ~PAGE_MASK || end & ~PAGE_MASK || start >= end
30 || start < 2 * PAGE_SIZE)
31 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
32
33 VCPU_EVENT(vcpu, 5, "diag release pages %lX %lX", start, end);
34
35 /*
36 * We checked for start >= end above, so lets check for the
37 * fast path (no prefix swap page involved)
38 */
39 if (end <= prefix || start >= prefix + 2 * PAGE_SIZE) {
40 gmap_discard(vcpu->arch.gmap, start, end);
41 } else {
42 /*
43 * This is slow path. gmap_discard will check for start
44 * so lets split this into before prefix, prefix, after
45 * prefix and let gmap_discard make some of these calls
46 * NOPs.
47 */
48 gmap_discard(vcpu->arch.gmap, start, prefix);
49 if (start <= prefix)
50 gmap_discard(vcpu->arch.gmap, 0, PAGE_SIZE);
51 if (end > prefix + PAGE_SIZE)
52 gmap_discard(vcpu->arch.gmap, PAGE_SIZE, 2 * PAGE_SIZE);
53 gmap_discard(vcpu->arch.gmap, prefix + 2 * PAGE_SIZE, end);
54 }
55 return 0;
56 }
57
__diag_page_ref_service(struct kvm_vcpu * vcpu)58 static int __diag_page_ref_service(struct kvm_vcpu *vcpu)
59 {
60 struct prs_parm {
61 u16 code;
62 u16 subcode;
63 u16 parm_len;
64 u16 parm_version;
65 u64 token_addr;
66 u64 select_mask;
67 u64 compare_mask;
68 u64 zarch;
69 };
70 struct prs_parm parm;
71 int rc;
72 u16 rx = (vcpu->arch.sie_block->ipa & 0xf0) >> 4;
73 u16 ry = (vcpu->arch.sie_block->ipa & 0x0f);
74
75 VCPU_EVENT(vcpu, 3, "diag page reference parameter block at 0x%llx",
76 vcpu->run->s.regs.gprs[rx]);
77 vcpu->stat.instruction_diagnose_258++;
78 if (vcpu->run->s.regs.gprs[rx] & 7)
79 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
80 rc = read_guest(vcpu, vcpu->run->s.regs.gprs[rx], rx, &parm, sizeof(parm));
81 if (rc)
82 return kvm_s390_inject_prog_cond(vcpu, rc);
83 if (parm.parm_version != 2 || parm.parm_len < 5 || parm.code != 0x258)
84 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
85
86 switch (parm.subcode) {
87 case 0: /* TOKEN */
88 VCPU_EVENT(vcpu, 3, "pageref token addr 0x%llx "
89 "select mask 0x%llx compare mask 0x%llx",
90 parm.token_addr, parm.select_mask, parm.compare_mask);
91 if (vcpu->arch.pfault_token != KVM_S390_PFAULT_TOKEN_INVALID) {
92 /*
93 * If the pagefault handshake is already activated,
94 * the token must not be changed. We have to return
95 * decimal 8 instead, as mandated in SC24-6084.
96 */
97 vcpu->run->s.regs.gprs[ry] = 8;
98 return 0;
99 }
100
101 if ((parm.compare_mask & parm.select_mask) != parm.compare_mask ||
102 parm.token_addr & 7 || parm.zarch != 0x8000000000000000ULL)
103 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
104
105 if (kvm_is_error_gpa(vcpu->kvm, parm.token_addr))
106 return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
107
108 vcpu->arch.pfault_token = parm.token_addr;
109 vcpu->arch.pfault_select = parm.select_mask;
110 vcpu->arch.pfault_compare = parm.compare_mask;
111 vcpu->run->s.regs.gprs[ry] = 0;
112 rc = 0;
113 break;
114 case 1: /*
115 * CANCEL
116 * Specification allows to let already pending tokens survive
117 * the cancel, therefore to reduce code complexity, we assume
118 * all outstanding tokens are already pending.
119 */
120 VCPU_EVENT(vcpu, 3, "pageref cancel addr 0x%llx", parm.token_addr);
121 if (parm.token_addr || parm.select_mask ||
122 parm.compare_mask || parm.zarch)
123 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
124
125 vcpu->run->s.regs.gprs[ry] = 0;
126 /*
127 * If the pfault handling was not established or is already
128 * canceled SC24-6084 requests to return decimal 4.
129 */
130 if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
131 vcpu->run->s.regs.gprs[ry] = 4;
132 else
133 vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
134
135 rc = 0;
136 break;
137 default:
138 rc = -EOPNOTSUPP;
139 break;
140 }
141
142 return rc;
143 }
144
__diag_time_slice_end(struct kvm_vcpu * vcpu)145 static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
146 {
147 VCPU_EVENT(vcpu, 5, "%s", "diag time slice end");
148 vcpu->stat.instruction_diagnose_44++;
149 kvm_vcpu_on_spin(vcpu, true);
150 return 0;
151 }
152
153 static int forward_cnt;
154 static unsigned long cur_slice;
155
diag9c_forwarding_overrun(void)156 static int diag9c_forwarding_overrun(void)
157 {
158 /* Reset the count on a new slice */
159 if (time_after(jiffies, cur_slice)) {
160 cur_slice = jiffies;
161 forward_cnt = diag9c_forwarding_hz / HZ;
162 }
163 return forward_cnt-- <= 0 ? 1 : 0;
164 }
165
__diag_time_slice_end_directed(struct kvm_vcpu * vcpu)166 static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
167 {
168 struct kvm_vcpu *tcpu;
169 int tcpu_cpu;
170 int tid;
171
172 tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
173 vcpu->stat.instruction_diagnose_9c++;
174
175 /* yield to self */
176 if (tid == vcpu->vcpu_id)
177 goto no_yield;
178
179 /* yield to invalid */
180 tcpu = kvm_get_vcpu_by_id(vcpu->kvm, tid);
181 if (!tcpu)
182 goto no_yield;
183
184 /* target guest VCPU already running */
185 tcpu_cpu = READ_ONCE(tcpu->cpu);
186 if (tcpu_cpu >= 0) {
187 if (!diag9c_forwarding_hz || diag9c_forwarding_overrun())
188 goto no_yield;
189
190 /* target host CPU already running */
191 if (!vcpu_is_preempted(tcpu_cpu))
192 goto no_yield;
193 smp_yield_cpu(tcpu_cpu);
194 VCPU_EVENT(vcpu, 5,
195 "diag time slice end directed to %d: yield forwarded",
196 tid);
197 vcpu->stat.diag_9c_forward++;
198 return 0;
199 }
200
201 if (kvm_vcpu_yield_to(tcpu) <= 0)
202 goto no_yield;
203
204 VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid);
205 return 0;
206 no_yield:
207 VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid);
208 vcpu->stat.diag_9c_ignored++;
209 return 0;
210 }
211
__diag_ipl_functions(struct kvm_vcpu * vcpu)212 static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
213 {
214 unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
215 unsigned long subcode = vcpu->run->s.regs.gprs[reg] & 0xffff;
216
217 VCPU_EVENT(vcpu, 3, "diag ipl functions, subcode %lx", subcode);
218 vcpu->stat.instruction_diagnose_308++;
219 switch (subcode) {
220 case 3:
221 vcpu->run->s390_reset_flags = KVM_S390_RESET_CLEAR;
222 break;
223 case 4:
224 vcpu->run->s390_reset_flags = 0;
225 break;
226 default:
227 return -EOPNOTSUPP;
228 }
229
230 /*
231 * no need to check the return value of vcpu_stop as it can only have
232 * an error for protvirt, but protvirt means user cpu state
233 */
234 if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
235 kvm_s390_vcpu_stop(vcpu);
236 vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
237 vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
238 vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
239 vcpu->run->exit_reason = KVM_EXIT_S390_RESET;
240 VCPU_EVENT(vcpu, 3, "requesting userspace resets %llx",
241 vcpu->run->s390_reset_flags);
242 trace_kvm_s390_request_resets(vcpu->run->s390_reset_flags);
243 return -EREMOTE;
244 }
245
__diag_virtio_hypercall(struct kvm_vcpu * vcpu)246 static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
247 {
248 int ret;
249
250 vcpu->stat.instruction_diagnose_500++;
251 /* No virtio-ccw notification? Get out quickly. */
252 if (!vcpu->kvm->arch.css_support ||
253 (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
254 return -EOPNOTSUPP;
255
256 VCPU_EVENT(vcpu, 4, "diag 0x500 schid 0x%8.8x queue 0x%x cookie 0x%llx",
257 (u32) vcpu->run->s.regs.gprs[2],
258 (u32) vcpu->run->s.regs.gprs[3],
259 vcpu->run->s.regs.gprs[4]);
260
261 /*
262 * The layout is as follows:
263 * - gpr 2 contains the subchannel id (passed as addr)
264 * - gpr 3 contains the virtqueue index (passed as datamatch)
265 * - gpr 4 contains the index on the bus (optionally)
266 */
267 ret = kvm_io_bus_write_cookie(vcpu, KVM_VIRTIO_CCW_NOTIFY_BUS,
268 vcpu->run->s.regs.gprs[2] & 0xffffffff,
269 8, &vcpu->run->s.regs.gprs[3],
270 vcpu->run->s.regs.gprs[4]);
271
272 /*
273 * Return cookie in gpr 2, but don't overwrite the register if the
274 * diagnose will be handled by userspace.
275 */
276 if (ret != -EOPNOTSUPP)
277 vcpu->run->s.regs.gprs[2] = ret;
278 /* kvm_io_bus_write_cookie returns -EOPNOTSUPP if it found no match. */
279 return ret < 0 ? ret : 0;
280 }
281
kvm_s390_handle_diag(struct kvm_vcpu * vcpu)282 int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
283 {
284 int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff;
285
286 if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
287 return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
288
289 trace_kvm_s390_handle_diag(vcpu, code);
290 switch (code) {
291 case 0x10:
292 return diag_release_pages(vcpu);
293 case 0x44:
294 return __diag_time_slice_end(vcpu);
295 case 0x9c:
296 return __diag_time_slice_end_directed(vcpu);
297 case 0x258:
298 return __diag_page_ref_service(vcpu);
299 case 0x308:
300 return __diag_ipl_functions(vcpu);
301 case 0x500:
302 return __diag_virtio_hypercall(vcpu);
303 default:
304 vcpu->stat.instruction_diagnose_other++;
305 return -EOPNOTSUPP;
306 }
307 }
308
