arch/s390/kvm/diag.c

   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/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
  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
  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
 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
 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
 166 static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
 167 {
 168         struct kvm_vcpu *tcpu;
 169         int tid;
 170
 171         tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
 172         vcpu->stat.instruction_diagnose_9c++;
 173
 174         /* yield to self */
 175         if (tid == vcpu->vcpu_id)
 176                 goto no_yield;
 177
 178         /* yield to invalid */
 179         tcpu = kvm_get_vcpu_by_id(vcpu->kvm, tid);
 180         if (!tcpu)
 181                 goto no_yield;
 182
 183         /* target guest VCPU already running */
 184         if (READ_ONCE(tcpu->cpu) >= 0) {
 185                 if (!diag9c_forwarding_hz || diag9c_forwarding_overrun())
 186                         goto no_yield;
 187
 188                 /* target host CPU already running */
 189                 if (!vcpu_is_preempted(tcpu->cpu))
 190                         goto no_yield;
 191                 smp_yield_cpu(tcpu->cpu);
 192                 VCPU_EVENT(vcpu, 5,
 193                            "diag time slice end directed to %d: yield forwarded",
 194                            tid);
 195                 vcpu->stat.diag_9c_forward++;
 196                 return 0;
 197         }
 198
 199         if (kvm_vcpu_yield_to(tcpu) <= 0)
 200                 goto no_yield;
 201
 202         VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid);
 203         return 0;
 204 no_yield:
 205         VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid);
 206         vcpu->stat.diag_9c_ignored++;
 207         return 0;
 208 }
 209
 210 static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
 211 {
 212         unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
 213         unsigned long subcode = vcpu->run->s.regs.gprs[reg] & 0xffff;
 214
 215         VCPU_EVENT(vcpu, 3, "diag ipl functions, subcode %lx", subcode);
 216         vcpu->stat.instruction_diagnose_308++;
 217         switch (subcode) {
 218         case 3:
 219                 vcpu->run->s390_reset_flags = KVM_S390_RESET_CLEAR;
 220                 break;
 221         case 4:
 222                 vcpu->run->s390_reset_flags = 0;
 223                 break;
 224         default:
 225                 return -EOPNOTSUPP;
 226         }
 227
 228         /*
 229          * no need to check the return value of vcpu_stop as it can only have
 230          * an error for protvirt, but protvirt means user cpu state
 231          */
 232         if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
 233                 kvm_s390_vcpu_stop(vcpu);
 234         vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
 235         vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
 236         vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
 237         vcpu->run->exit_reason = KVM_EXIT_S390_RESET;
 238         VCPU_EVENT(vcpu, 3, "requesting userspace resets %llx",
 239           vcpu->run->s390_reset_flags);
 240         trace_kvm_s390_request_resets(vcpu->run->s390_reset_flags);
 241         return -EREMOTE;
 242 }
 243
 244 static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
 245 {
 246         int ret;
 247
 248         vcpu->stat.instruction_diagnose_500++;
 249         /* No virtio-ccw notification? Get out quickly. */
 250         if (!vcpu->kvm->arch.css_support ||
 251             (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
 252                 return -EOPNOTSUPP;
 253
 254         VCPU_EVENT(vcpu, 4, "diag 0x500 schid 0x%8.8x queue 0x%x cookie 0x%llx",
 255                             (u32) vcpu->run->s.regs.gprs[2],
 256                             (u32) vcpu->run->s.regs.gprs[3],
 257                             vcpu->run->s.regs.gprs[4]);
 258
 259         /*
 260          * The layout is as follows:
 261          * - gpr 2 contains the subchannel id (passed as addr)
 262          * - gpr 3 contains the virtqueue index (passed as datamatch)
 263          * - gpr 4 contains the index on the bus (optionally)
 264          */
 265         ret = kvm_io_bus_write_cookie(vcpu, KVM_VIRTIO_CCW_NOTIFY_BUS,
 266                                       vcpu->run->s.regs.gprs[2] & 0xffffffff,
 267                                       8, &vcpu->run->s.regs.gprs[3],
 268                                       vcpu->run->s.regs.gprs[4]);
 269
 270         /*
 271          * Return cookie in gpr 2, but don't overwrite the register if the
 272          * diagnose will be handled by userspace.
 273          */
 274         if (ret != -EOPNOTSUPP)
 275                 vcpu->run->s.regs.gprs[2] = ret;
 276         /* kvm_io_bus_write_cookie returns -EOPNOTSUPP if it found no match. */
 277         return ret < 0 ? ret : 0;
 278 }
 279
 280 int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
 281 {
 282         int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff;
 283
 284         if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
 285                 return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
 286
 287         trace_kvm_s390_handle_diag(vcpu, code);
 288         switch (code) {
 289         case 0x10:
 290                 return diag_release_pages(vcpu);
 291         case 0x44:
 292                 return __diag_time_slice_end(vcpu);
 293         case 0x9c:
 294                 return __diag_time_slice_end_directed(vcpu);
 295         case 0x258:
 296                 return __diag_page_ref_service(vcpu);
 297         case 0x308:
 298                 return __diag_ipl_functions(vcpu);
 299         case 0x500:
 300                 return __diag_virtio_hypercall(vcpu);
 301         default:
 302                 vcpu->stat.instruction_diagnose_other++;
 303                 return -EOPNOTSUPP;
 304         }
 305 }