tools/testing/selftests/kvm/lib/s390x/ucall.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * ucall support. A ucall is a "hypercall to userspace".
   4  *
   5  * Copyright (C) 2019 Red Hat, Inc.
   6  */
   7 #include "kvm_util.h"
   8
   9 void ucall_init(struct kvm_vm *vm, void *arg)
  10 {
  11 }
  12
  13 void ucall_uninit(struct kvm_vm *vm)
  14 {
  15 }
  16
  17 void ucall(uint64_t cmd, int nargs, ...)
  18 {
  19         struct ucall uc = {
  20                 .cmd = cmd,
  21         };
  22         va_list va;
  23         int i;
  24
  25         nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS;
  26
  27         va_start(va, nargs);
  28         for (i = 0; i < nargs; ++i)
  29                 uc.args[i] = va_arg(va, uint64_t);
  30         va_end(va);
  31
  32         /* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */
  33         asm volatile ("diag 0,%0,0x501" : : "a"(&uc) : "memory");
  34 }
  35
  36 uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
  37 {
  38         struct kvm_run *run = vcpu_state(vm, vcpu_id);
  39         struct ucall ucall = {};
  40
  41         if (uc)
  42                 memset(uc, 0, sizeof(*uc));
  43
  44         if (run->exit_reason == KVM_EXIT_S390_SIEIC &&
  45             run->s390_sieic.icptcode == 4 &&
  46             (run->s390_sieic.ipa >> 8) == 0x83 &&    /* 0x83 means DIAGNOSE */
  47             (run->s390_sieic.ipb >> 16) == 0x501) {
  48                 int reg = run->s390_sieic.ipa & 0xf;
  49
  50                 memcpy(&ucall, addr_gva2hva(vm, run->s.regs.gprs[reg]),
  51                        sizeof(ucall));
  52
  53                 vcpu_run_complete_io(vm, vcpu_id);
  54                 if (uc)
  55                         memcpy(uc, &ucall, sizeof(ucall));
  56         }
  57
  58         return ucall.cmd;
  59 }