LXR linux/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
   9void ucall_init(struct kvm_vm *vm, void *arg)
  10{
  11}
  12
  13void ucall_uninit(struct kvm_vm *vm)
  14{
  15}
  16
  17void 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
  36uint64_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}
  60