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 <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/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 }