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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 <[email protected]>
8  *               Christian Borntraeger <[email protected]>
9  */
10
11 #include <linux/kvm.h>
12 #include <linux/kvm_host.h>
13 #include <asm/pgalloc.h>
14 #include <asm/gmap.h>
15 #include <asm/virtio-ccw.h>
16 #include "kvm-s390.h"
17 #include "trace.h"
18 #include "trace-s390.h"
19 #include "gaccess.h"
20
21 static int diag_release_pages(struct kvm_vcpu *vcpu)
22 {
23         unsigned long start, end;
24         unsigned long prefix  = kvm_s390_get_prefix(vcpu);
25
26         start = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
27         end = vcpu->run->s.regs.gprs[vcpu->arch.sie_block->ipa & 0xf] + PAGE_SIZE;
28         vcpu->stat.diagnose_10++;
29
30         if (start & ~PAGE_MASK || end & ~PAGE_MASK || start >= end
31             || start < 2 * PAGE_SIZE)
32                 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
33
34         VCPU_EVENT(vcpu, 5, "diag release pages %lX %lX", start, end);
35
36         /*
37          * We checked for start >= end above, so lets check for the
38          * fast path (no prefix swap page involved)
39          */
40         if (end <= prefix || start >= prefix + 2 * PAGE_SIZE) {
41                 gmap_discard(vcpu->arch.gmap, start, end);
42         } else {
43                 /*
44                  * This is slow path.  gmap_discard will check for start
45                  * so lets split this into before prefix, prefix, after
46                  * prefix and let gmap_discard make some of these calls
47                  * NOPs.
48                  */
49                 gmap_discard(vcpu->arch.gmap, start, prefix);
50                 if (start <= prefix)
51                         gmap_discard(vcpu->arch.gmap, 0, PAGE_SIZE);
52                 if (end > prefix + PAGE_SIZE)
53                         gmap_discard(vcpu->arch.gmap, PAGE_SIZE, 2 * PAGE_SIZE);
54                 gmap_discard(vcpu->arch.gmap, prefix + 2 * PAGE_SIZE, end);
55         }
56         return 0;
57 }
58
59 static int __diag_page_ref_service(struct kvm_vcpu *vcpu)
60 {
61         struct prs_parm {
62                 u16 code;
63                 u16 subcode;
64                 u16 parm_len;
65                 u16 parm_version;
66                 u64 token_addr;
67                 u64 select_mask;
68                 u64 compare_mask;
69                 u64 zarch;
70         };
71         struct prs_parm parm;
72         int rc;
73         u16 rx = (vcpu->arch.sie_block->ipa & 0xf0) >> 4;
74         u16 ry = (vcpu->arch.sie_block->ipa & 0x0f);
75
76         VCPU_EVENT(vcpu, 3, "diag page reference parameter block at 0x%llx",
77                    vcpu->run->s.regs.gprs[rx]);
78         vcpu->stat.diagnose_258++;
79         if (vcpu->run->s.regs.gprs[rx] & 7)
80                 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
81         rc = read_guest(vcpu, vcpu->run->s.regs.gprs[rx], rx, &parm, sizeof(parm));
82         if (rc)
83                 return kvm_s390_inject_prog_cond(vcpu, rc);
84         if (parm.parm_version != 2 || parm.parm_len < 5 || parm.code != 0x258)
85                 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
86
87         switch (parm.subcode) {
88         case 0: /* TOKEN */
89                 VCPU_EVENT(vcpu, 3, "pageref token addr 0x%llx "
90                            "select mask 0x%llx compare mask 0x%llx",
91                            parm.token_addr, parm.select_mask, parm.compare_mask);
92                 if (vcpu->arch.pfault_token != KVM_S390_PFAULT_TOKEN_INVALID) {
93                         /*
94                          * If the pagefault handshake is already activated,
95                          * the token must not be changed.  We have to return
96                          * decimal 8 instead, as mandated in SC24-6084.
97                          */
98                         vcpu->run->s.regs.gprs[ry] = 8;
99                         return 0;
100                 }
101
102                 if ((parm.compare_mask & parm.select_mask) != parm.compare_mask ||
103                     parm.token_addr & 7 || parm.zarch != 0x8000000000000000ULL)
104                         return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
105
106                 if (kvm_is_error_gpa(vcpu->kvm, parm.token_addr))
107                         return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
108
109                 vcpu->arch.pfault_token = parm.token_addr;
110                 vcpu->arch.pfault_select = parm.select_mask;
111                 vcpu->arch.pfault_compare = parm.compare_mask;
112                 vcpu->run->s.regs.gprs[ry] = 0;
113                 rc = 0;
114                 break;
115         case 1: /*
116                  * CANCEL
117                  * Specification allows to let already pending tokens survive
118                  * the cancel, therefore to reduce code complexity, we assume
119                  * all outstanding tokens are already pending.
120                  */
121                 VCPU_EVENT(vcpu, 3, "pageref cancel addr 0x%llx", parm.token_addr);
122                 if (parm.token_addr || parm.select_mask ||
123                     parm.compare_mask || parm.zarch)
124                         return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
125
126                 vcpu->run->s.regs.gprs[ry] = 0;
127                 /*
128                  * If the pfault handling was not established or is already
129                  * canceled SC24-6084 requests to return decimal 4.
130                  */
131                 if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
132                         vcpu->run->s.regs.gprs[ry] = 4;
133                 else
134                         vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
135
136                 rc = 0;
137                 break;
138         default:
139                 rc = -EOPNOTSUPP;
140                 break;
141         }
142
143         return rc;
144 }
145
146 static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
147 {
148         VCPU_EVENT(vcpu, 5, "%s", "diag time slice end");
149         vcpu->stat.diagnose_44++;
150         kvm_vcpu_on_spin(vcpu, true);
151         return 0;
152 }
153
154 static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
155 {
156         struct kvm_vcpu *tcpu;
157         int tid;
158
159         tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
160         vcpu->stat.diagnose_9c++;
161
162         /* yield to self */
163         if (tid == vcpu->vcpu_id)
164                 goto no_yield;
165
166         /* yield to invalid */
167         tcpu = kvm_get_vcpu_by_id(vcpu->kvm, tid);
168         if (!tcpu)
169                 goto no_yield;
170
171         /* target already running */
172         if (READ_ONCE(tcpu->cpu) >= 0)
173                 goto no_yield;
174
175         if (kvm_vcpu_yield_to(tcpu) <= 0)
176                 goto no_yield;
177
178         VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid);
179         return 0;
180 no_yield:
181         VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid);
182         vcpu->stat.diagnose_9c_ignored++;
183         return 0;
184 }
185
186 static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
187 {
188         unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
189         unsigned long subcode = vcpu->run->s.regs.gprs[reg] & 0xffff;
190
191         VCPU_EVENT(vcpu, 3, "diag ipl functions, subcode %lx", subcode);
192         vcpu->stat.diagnose_308++;
193         switch (subcode) {
194         case 3:
195                 vcpu->run->s390_reset_flags = KVM_S390_RESET_CLEAR;
196                 break;
197         case 4:
198                 vcpu->run->s390_reset_flags = 0;
199                 break;
200         default:
201                 return -EOPNOTSUPP;
202         }
203
204         /*
205          * no need to check the return value of vcpu_stop as it can only have
206          * an error for protvirt, but protvirt means user cpu state
207          */
208         if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
209                 kvm_s390_vcpu_stop(vcpu);
210         vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
211         vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
212         vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
213         vcpu->run->exit_reason = KVM_EXIT_S390_RESET;
214         VCPU_EVENT(vcpu, 3, "requesting userspace resets %llx",
215           vcpu->run->s390_reset_flags);
216         trace_kvm_s390_request_resets(vcpu->run->s390_reset_flags);
217         return -EREMOTE;
218 }
219
220 static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
221 {
222         int ret;
223
224         vcpu->stat.diagnose_500++;
225         /* No virtio-ccw notification? Get out quickly. */
226         if (!vcpu->kvm->arch.css_support ||
227             (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
228                 return -EOPNOTSUPP;
229
230         VCPU_EVENT(vcpu, 4, "diag 0x500 schid 0x%8.8x queue 0x%x cookie 0x%llx",
231                             (u32) vcpu->run->s.regs.gprs[2],
232                             (u32) vcpu->run->s.regs.gprs[3],
233                             vcpu->run->s.regs.gprs[4]);
234
235         /*
236          * The layout is as follows:
237          * - gpr 2 contains the subchannel id (passed as addr)
238          * - gpr 3 contains the virtqueue index (passed as datamatch)
239          * - gpr 4 contains the index on the bus (optionally)
240          */
241         ret = kvm_io_bus_write_cookie(vcpu, KVM_VIRTIO_CCW_NOTIFY_BUS,
242                                       vcpu->run->s.regs.gprs[2] & 0xffffffff,
243                                       8, &vcpu->run->s.regs.gprs[3],
244                                       vcpu->run->s.regs.gprs[4]);
245
246         /*
247          * Return cookie in gpr 2, but don't overwrite the register if the
248          * diagnose will be handled by userspace.
249          */
250         if (ret != -EOPNOTSUPP)
251                 vcpu->run->s.regs.gprs[2] = ret;
252         /* kvm_io_bus_write_cookie returns -EOPNOTSUPP if it found no match. */
253         return ret < 0 ? ret : 0;
254 }
255
256 int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
257 {
258         int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff;
259
260         if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
261                 return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
262
263         trace_kvm_s390_handle_diag(vcpu, code);
264         switch (code) {
265         case 0x10:
266                 return diag_release_pages(vcpu);
267         case 0x44:
268                 return __diag_time_slice_end(vcpu);
269         case 0x9c:
270                 return __diag_time_slice_end_directed(vcpu);
271         case 0x258:
272                 return __diag_page_ref_service(vcpu);
273         case 0x308:
274                 return __diag_ipl_functions(vcpu);
275         case 0x500:
276                 return __diag_virtio_hypercall(vcpu);
277         default:
278                 vcpu->stat.diagnose_other++;
279                 return -EOPNOTSUPP;
280         }
281 }
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