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
ucall_init(struct kvm_vm * vm,void * arg)9 void ucall_init(struct kvm_vm *vm, void *arg)
10 {
11 }
12
ucall_uninit(struct kvm_vm * vm)13 void ucall_uninit(struct kvm_vm *vm)
14 {
15 }
16
ucall(uint64_t cmd,int nargs,...)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
get_ucall(struct kvm_vm * vm,uint32_t vcpu_id,struct ucall * uc)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 (run->exit_reason == KVM_EXIT_S390_SIEIC &&
42 run->s390_sieic.icptcode == 4 &&
43 (run->s390_sieic.ipa >> 8) == 0x83 && /* 0x83 means DIAGNOSE */
44 (run->s390_sieic.ipb >> 16) == 0x501) {
45 int reg = run->s390_sieic.ipa & 0xf;
46
47 memcpy(&ucall, addr_gva2hva(vm, run->s.regs.gprs[reg]),
48 sizeof(ucall));
49
50 vcpu_run_complete_io(vm, vcpu_id);
51 if (uc)
52 memcpy(uc, &ucall, sizeof(ucall));
53 }
54
55 return ucall.cmd;
56 }
57