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_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa) 10 { 11 } 12 13 void ucall_arch_do_ucall(vm_vaddr_t uc) 14 { 15 /* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */ 16 asm volatile ("diag 0,%0,0x501" : : "a"(uc) : "memory"); 17 } 18 19 void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu) 20 { 21 struct kvm_run *run = vcpu->run; 22 23 if (run->exit_reason == KVM_EXIT_S390_SIEIC && 24 run->s390_sieic.icptcode == 4 && 25 (run->s390_sieic.ipa >> 8) == 0x83 && /* 0x83 means DIAGNOSE */ 26 (run->s390_sieic.ipb >> 16) == 0x501) { 27 int reg = run->s390_sieic.ipa & 0xf; 28 29 return (void *)run->s.regs.gprs[reg]; 30 } 31 return NULL; 32 } 33