ucall.c

// SPDX-License-Identifier: GPL-2.0
/*
 * ucall support. A ucall is a "hypercall to userspace".
 *
 * Copyright (C) 2019 Red Hat, Inc.
 */
#include "kvm_util.h"

void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
{
	struct kvm_run *run = vcpu->run;

	if (run->exit_reason == KVM_EXIT_S390_SIEIC &&
	    run->s390_sieic.icptcode == 4 &&
	    (run->s390_sieic.ipa >> 8) == 0x83 &&    /* 0x83 means DIAGNOSE */
	    (run->s390_sieic.ipb >> 16) == 0x501) {
		int reg = run->s390_sieic.ipa & 0xf;

		return (void *)run->s.regs.gprs[reg];
	}
	return NULL;
}