// SPDX-License-Identifier: GPL-2.0
/*
 * handling interprocessor communication
 *
 * Copyright IBM Corp. 2008, 2013
 *
 *    Author(s): Carsten Otte <cotte@de.ibm.com>
 *               Christian Borntraeger <borntraeger@de.ibm.com>
 *               Christian Ehrhardt <ehrhardt@de.ibm.com>
 */

#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <asm/sigp.h>
#include "gaccess.h"
#include "kvm-s390.h"
#include "trace.h"

static int __sigp_sense(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,
			u64 *reg)
{
	const bool stopped = kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED);
	int rc;
	int ext_call_pending;

	ext_call_pending = kvm_s390_ext_call_pending(dst_vcpu);
	if (!stopped && !ext_call_pending)
		rc = SIGP_CC_ORDER_CODE_ACCEPTED;
	else {
		*reg &= 0xffffffff00000000UL;
		if (ext_call_pending)
			*reg |= SIGP_STATUS_EXT_CALL_PENDING;
		if (stopped)
			*reg |= SIGP_STATUS_STOPPED;
		rc = SIGP_CC_STATUS_STORED;
	}

	VCPU_EVENT(vcpu, 4, "sensed status of cpu %x rc %x", dst_vcpu->vcpu_id,
		   rc);
	return rc;
}

static int __inject_sigp_emergency(struct kvm_vcpu *vcpu,
				    struct kvm_vcpu *dst_vcpu)
{
	struct kvm_s390_irq irq = {
		.type = KVM_S390_INT_EMERGENCY,
		.u.emerg.code = vcpu->vcpu_id,
	};
	int rc = 0;

	rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
	if (!rc)
		VCPU_EVENT(vcpu, 4, "sent sigp emerg to cpu %x",
			   dst_vcpu->vcpu_id);

	return rc ? rc : SIGP_CC_ORDER_CODE_ACCEPTED;
}

static int __sigp_emergency(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu)
{
	return __inject_sigp_emergency(vcpu, dst_vcpu);
}

static int __sigp_conditional_emergency(struct kvm_vcpu *vcpu,
					struct kvm_vcpu *dst_vcpu,
					u16 asn, u64 *reg)
{
	const u64 psw_int_mask = PSW_MASK_IO | PSW_MASK_EXT;
	u16 p_asn, s_asn;
	psw_t *psw;
	bool idle;

	idle = is_vcpu_idle(vcpu);
	psw = &dst_vcpu->arch.sie_block->gpsw;
	p_asn = dst_vcpu->arch.sie_block->gcr[4] & 0xffff;  /* Primary ASN */
	s_asn = dst_vcpu->arch.sie_block->gcr[3] & 0xffff;  /* Secondary ASN */

	/* Inject the emergency signal? */
	if (!is_vcpu_stopped(vcpu)
	    || (psw->mask & psw_int_mask) != psw_int_mask
	    || (idle && psw->addr != 0)
	    || (!idle && (asn == p_asn || asn == s_asn))) {
		return __inject_sigp_emergency(vcpu, dst_vcpu);
	} else {
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_INCORRECT_STATE;
		return SIGP_CC_STATUS_STORED;
	}
}

static int __sigp_external_call(struct kvm_vcpu *vcpu,
				struct kvm_vcpu *dst_vcpu, u64 *reg)
{
	struct kvm_s390_irq irq = {
		.type = KVM_S390_INT_EXTERNAL_CALL,
		.u.extcall.code = vcpu->vcpu_id,
	};
	int rc;

	rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
	if (rc == -EBUSY) {
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_EXT_CALL_PENDING;
		return SIGP_CC_STATUS_STORED;
	} else if (rc == 0) {
		VCPU_EVENT(vcpu, 4, "sent sigp ext call to cpu %x",
			   dst_vcpu->vcpu_id);
	}

	return rc ? rc : SIGP_CC_ORDER_CODE_ACCEPTED;
}

static int __sigp_stop(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu)
{
	struct kvm_s390_irq irq = {
		.type = KVM_S390_SIGP_STOP,
	};
	int rc;

	rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
	if (rc == -EBUSY)
		rc = SIGP_CC_BUSY;
	else if (rc == 0)
		VCPU_EVENT(vcpu, 4, "sent sigp stop to cpu %x",
			   dst_vcpu->vcpu_id);

	return rc;
}

static int __sigp_stop_and_store_status(struct kvm_vcpu *vcpu,
					struct kvm_vcpu *dst_vcpu, u64 *reg)
{
	struct kvm_s390_irq irq = {
		.type = KVM_S390_SIGP_STOP,
		.u.stop.flags = KVM_S390_STOP_FLAG_STORE_STATUS,
	};
	int rc;

	rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
	if (rc == -EBUSY)
		rc = SIGP_CC_BUSY;
	else if (rc == 0)
		VCPU_EVENT(vcpu, 4, "sent sigp stop and store status to cpu %x",
			   dst_vcpu->vcpu_id);

	return rc;
}

static int __sigp_set_arch(struct kvm_vcpu *vcpu, u32 parameter,
			   u64 *status_reg)
{
	*status_reg &= 0xffffffff00000000UL;

	/* Reject set arch order, with czam we're always in z/Arch mode. */
	*status_reg |= SIGP_STATUS_INVALID_PARAMETER;
	return SIGP_CC_STATUS_STORED;
}

static int __sigp_set_prefix(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,
			     u32 address, u64 *reg)
{
	struct kvm_s390_irq irq = {
		.type = KVM_S390_SIGP_SET_PREFIX,
		.u.prefix.address = address & 0x7fffe000u,
	};
	int rc;

	/*
	 * Make sure the new value is valid memory. We only need to check the
	 * first page, since address is 8k aligned and memory pieces are always
	 * at least 1MB aligned and have at least a size of 1MB.
	 */
	if (kvm_is_error_gpa(vcpu->kvm, irq.u.prefix.address)) {
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_INVALID_PARAMETER;
		return SIGP_CC_STATUS_STORED;
	}

	rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
	if (rc == -EBUSY) {
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_INCORRECT_STATE;
		return SIGP_CC_STATUS_STORED;
	}

	return rc;
}

static int __sigp_store_status_at_addr(struct kvm_vcpu *vcpu,
				       struct kvm_vcpu *dst_vcpu,
				       u32 addr, u64 *reg)
{
	int rc;

	if (!kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED)) {
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_INCORRECT_STATE;
		return SIGP_CC_STATUS_STORED;
	}

	addr &= 0x7ffffe00;
	rc = kvm_s390_store_status_unloaded(dst_vcpu, addr);
	if (rc == -EFAULT) {
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_INVALID_PARAMETER;
		rc = SIGP_CC_STATUS_STORED;
	}
	return rc;
}

static int __sigp_sense_running(struct kvm_vcpu *vcpu,
				struct kvm_vcpu *dst_vcpu, u64 *reg)
{
	int rc;

	if (!test_kvm_facility(vcpu->kvm, 9)) {
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_INVALID_ORDER;
		return SIGP_CC_STATUS_STORED;
	}

	if (kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_RUNNING)) {
		/* running */
		rc = SIGP_CC_ORDER_CODE_ACCEPTED;
	} else {
		/* not running */
		*reg &= 0xffffffff00000000UL;
		*reg |= SIGP_STATUS_NOT_RUNNING;
		rc = SIGP_CC_STATUS_STORED;
	}

	VCPU_EVENT(vcpu, 4, "sensed running status of cpu %x rc %x",
		   dst_vcpu->vcpu_id, rc);

	return rc;
}

static int __prepare_sigp_re_start(struct kvm_vcpu *vcpu,
				   struct kvm_vcpu *dst_vcpu, u8 order_code)
{
	struct kvm_s390_local_interrupt *li = &dst_vcpu->arch.local_int;
	/* handle (RE)START in user space */
	int rc = -EOPNOTSUPP;

	/* make sure we don't race with STOP irq injection */
	spin_lock(&li->lock);
	if (kvm_s390_is_stop_irq_pending(dst_vcpu))
		rc = SIGP_CC_BUSY;
	spin_unlock(&li->lock);

	return rc;
}

static int __prepare_sigp_cpu_reset(struct kvm_vcpu *vcpu,
				    struct kvm_vcpu *dst_vcpu, u8 order_code)
{
	/* handle (INITIAL) CPU RESET in user space */
	return -EOPNOTSUPP;
}

static int __prepare_sigp_unknown(struct kvm_vcpu *vcpu,
				  struct kvm_vcpu *dst_vcpu)
{
	/* handle unknown orders in user space */
	return -EOPNOTSUPP;
}

static int handle_sigp_dst(struct kvm_vcpu *vcpu, u8 order_code,
			   u16 cpu_addr, u32 parameter, u64 *status_reg)
{
	int rc;
	struct kvm_vcpu *dst_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);

	if (!dst_vcpu)
		return SIGP_CC_NOT_OPERATIONAL;

	/*
	 * SIGP RESTART, SIGP STOP, and SIGP STOP AND STORE STATUS orders
	 * are processed asynchronously. Until the affected VCPU finishes
	 * its work and calls back into KVM to clear the (RESTART or STOP)
	 * interrupt, we need to return any new non-reset orders "busy".
	 *
	 * This is important because a single VCPU could issue:
	 *  1) SIGP STOP $DESTINATION
	 *  2) SIGP SENSE $DESTINATION
	 *
	 * If the SIGP SENSE would not be rejected as "busy", it could
	 * return an incorrect answer as to whether the VCPU is STOPPED
	 * or OPERATING.
	 */
	if (order_code != SIGP_INITIAL_CPU_RESET &&
	    order_code != SIGP_CPU_RESET) {
		/*
		 * Lockless check. Both SIGP STOP and SIGP (RE)START
		 * properly synchronize everything while processing
		 * their orders, while the guest cannot observe a
		 * difference when issuing other orders from two
		 * different VCPUs.
		 */
		if (kvm_s390_is_stop_irq_pending(dst_vcpu) ||
		    kvm_s390_is_restart_irq_pending(dst_vcpu))
			return SIGP_CC_BUSY;
	}

	switch (order_code) {
	case SIGP_SENSE:
		vcpu->stat.instruction_sigp_sense++;
		rc = __sigp_sense(vcpu, dst_vcpu, status_reg);
		break;
	case SIGP_EXTERNAL_CALL:
		vcpu->stat.instruction_sigp_external_call++;
		rc = __sigp_external_call(vcpu, dst_vcpu, status_reg);
		break;
	case SIGP_EMERGENCY_SIGNAL:
		vcpu->stat.instruction_sigp_emergency++;
		rc = __sigp_emergency(vcpu, dst_vcpu);
		break;
	case SIGP_STOP:
		vcpu->stat.instruction_sigp_stop++;
		rc = __sigp_stop(vcpu, dst_vcpu);
		break;
	case SIGP_STOP_AND_STORE_STATUS:
		vcpu->stat.instruction_sigp_stop_store_status++;
		rc = __sigp_stop_and_store_status(vcpu, dst_vcpu, status_reg);
		break;
	case SIGP_STORE_STATUS_AT_ADDRESS:
		vcpu->stat.instruction_sigp_store_status++;
		rc = __sigp_store_status_at_addr(vcpu, dst_vcpu, parameter,
						 status_reg);
		break;
	case SIGP_SET_PREFIX:
		vcpu->stat.instruction_sigp_prefix++;
		rc = __sigp_set_prefix(vcpu, dst_vcpu, parameter, status_reg);
		break;
	case SIGP_COND_EMERGENCY_SIGNAL:
		vcpu->stat.instruction_sigp_cond_emergency++;
		rc = __sigp_conditional_emergency(vcpu, dst_vcpu, parameter,
						  status_reg);
		break;
	case SIGP_SENSE_RUNNING:
		vcpu->stat.instruction_sigp_sense_running++;
		rc = __sigp_sense_running(vcpu, dst_vcpu, status_reg);
		break;
	case SIGP_START:
		vcpu->stat.instruction_sigp_start++;
		rc = __prepare_sigp_re_start(vcpu, dst_vcpu, order_code);
		break;
	case SIGP_RESTART:
		vcpu->stat.instruction_sigp_restart++;
		rc = __prepare_sigp_re_start(vcpu, dst_vcpu, order_code);
		break;
	case SIGP_INITIAL_CPU_RESET:
		vcpu->stat.instruction_sigp_init_cpu_reset++;
		rc = __prepare_sigp_cpu_reset(vcpu, dst_vcpu, order_code);
		break;
	case SIGP_CPU_RESET:
		vcpu->stat.instruction_sigp_cpu_reset++;
		rc = __prepare_sigp_cpu_reset(vcpu, dst_vcpu, order_code);
		break;
	default:
		vcpu->stat.instruction_sigp_unknown++;
		rc = __prepare_sigp_unknown(vcpu, dst_vcpu);
	}

	if (rc == -EOPNOTSUPP)
		VCPU_EVENT(vcpu, 4,
			   "sigp order %u -> cpu %x: handled in user space",
			   order_code, dst_vcpu->vcpu_id);

	return rc;
}

static int handle_sigp_order_in_user_space(struct kvm_vcpu *vcpu, u8 order_code,
					   u16 cpu_addr)
{
	if (!vcpu->kvm->arch.user_sigp)
		return 0;

	switch (order_code) {
	case SIGP_SENSE:
	case SIGP_EXTERNAL_CALL:
	case SIGP_EMERGENCY_SIGNAL:
	case SIGP_COND_EMERGENCY_SIGNAL:
	case SIGP_SENSE_RUNNING:
		return 0;
	/* update counters as we're directly dropping to user space */
	case SIGP_STOP:
		vcpu->stat.instruction_sigp_stop++;
		break;
	case SIGP_STOP_AND_STORE_STATUS:
		vcpu->stat.instruction_sigp_stop_store_status++;
		break;
	case SIGP_STORE_STATUS_AT_ADDRESS:
		vcpu->stat.instruction_sigp_store_status++;
		break;
	case SIGP_STORE_ADDITIONAL_STATUS:
		vcpu->stat.instruction_sigp_store_adtl_status++;
		break;
	case SIGP_SET_PREFIX:
		vcpu->stat.instruction_sigp_prefix++;
		break;
	case SIGP_START:
		vcpu->stat.instruction_sigp_start++;
		break;
	case SIGP_RESTART:
		vcpu->stat.instruction_sigp_restart++;
		break;
	case SIGP_INITIAL_CPU_RESET:
		vcpu->stat.instruction_sigp_init_cpu_reset++;
		break;
	case SIGP_CPU_RESET:
		vcpu->stat.instruction_sigp_cpu_reset++;
		break;
	default:
		vcpu->stat.instruction_sigp_unknown++;
	}
	VCPU_EVENT(vcpu, 3, "SIGP: order %u for CPU %d handled in userspace",
		   order_code, cpu_addr);

	return 1;
}

int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu)
{
	int r1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
	int r3 = vcpu->arch.sie_block->ipa & 0x000f;
	u32 parameter;
	u16 cpu_addr = vcpu->run->s.regs.gprs[r3];
	u8 order_code;
	int rc;

	/* sigp in userspace can exit */
	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);

	order_code = kvm_s390_get_base_disp_rs(vcpu, NULL);
	if (handle_sigp_order_in_user_space(vcpu, order_code, cpu_addr))
		return -EOPNOTSUPP;

	if (r1 % 2)
		parameter = vcpu->run->s.regs.gprs[r1];
	else
		parameter = vcpu->run->s.regs.gprs[r1 + 1];

	trace_kvm_s390_handle_sigp(vcpu, order_code, cpu_addr, parameter);
	switch (order_code) {
	case SIGP_SET_ARCHITECTURE:
		vcpu->stat.instruction_sigp_arch++;
		rc = __sigp_set_arch(vcpu, parameter,
				     &vcpu->run->s.regs.gprs[r1]);
		break;
	default:
		rc = handle_sigp_dst(vcpu, order_code, cpu_addr,
				     parameter,
				     &vcpu->run->s.regs.gprs[r1]);
	}

	if (rc < 0)
		return rc;

	kvm_s390_set_psw_cc(vcpu, rc);
	return 0;
}

/*
 * Handle SIGP partial execution interception.
 *
 * This interception will occur at the source cpu when a source cpu sends an
 * external call to a target cpu and the target cpu has the WAIT bit set in
 * its cpuflags. Interception will occurr after the interrupt indicator bits at
 * the target cpu have been set. All error cases will lead to instruction
 * interception, therefore nothing is to be checked or prepared.
 */
int kvm_s390_handle_sigp_pei(struct kvm_vcpu *vcpu)
{
	int r3 = vcpu->arch.sie_block->ipa & 0x000f;
	u16 cpu_addr = vcpu->run->s.regs.gprs[r3];
	struct kvm_vcpu *dest_vcpu;
	u8 order_code = kvm_s390_get_base_disp_rs(vcpu, NULL);

	if (order_code == SIGP_EXTERNAL_CALL) {
		trace_kvm_s390_handle_sigp_pei(vcpu, order_code, cpu_addr);

		dest_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);
		BUG_ON(dest_vcpu == NULL);

		kvm_s390_vcpu_wakeup(dest_vcpu);
		kvm_s390_set_psw_cc(vcpu, SIGP_CC_ORDER_CODE_ACCEPTED);
		return 0;
	}

	return -EOPNOTSUPP;
}