src/hf_ipi.c

/*
 * Copyright 2024 The Hafnium Authors.
 *
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file or at
 * https://opensource.org/licenses/BSD-3-Clause.
 */

#include "hf/hf_ipi.h"

#include "hf/arch/plat/ffa/notifications.h"

#include "hf/cpu.h"
#include "hf/plat/interrupts.h"

/** Interrupt priority for Inter-Processor Interrupt. */
#define IPI_PRIORITY 0x0U

/**
 * Initialize the IPI SGI.
 */
void hf_ipi_init_interrupt(void)
{
	/* Configure as a Secure SGI. */
	struct interrupt_descriptor ipi_desc = {
		.interrupt_id = HF_IPI_INTID,
		.type = INT_DESC_TYPE_SGI,
		.sec_state = INT_DESC_SEC_STATE_S,
		.priority = IPI_PRIORITY,
		.valid = true,
		.enabled = true,
	};

	plat_interrupts_configure_interrupt(ipi_desc);
}

/**
 * Returns the target_vcpu for the pending IPI on the current CPU and
 * resets the item in the list to NULL to show it has been retrieved.
 */
struct vcpu *hf_ipi_get_pending_target_vcpu(struct cpu *current)
{
	struct vcpu *ret;

	sl_lock(&current->lock);

	ret = current->ipi_target_vcpu;

	current->ipi_target_vcpu = NULL;

	sl_unlock(&current->lock);

	return ret;
}

/**
 * Send and record the IPI for the target vCPU.
 */
void hf_ipi_send_interrupt(struct vm *vm, ffa_vcpu_index_t target_vcpu_index)
{
	struct vcpu *target_vcpu = vm_get_vcpu(vm, target_vcpu_index);
	struct cpu *target_cpu = target_vcpu->cpu;

	sl_lock(&target_cpu->lock);

	target_cpu->ipi_target_vcpu = target_vcpu;

	sl_unlock(&target_cpu->lock);
	plat_interrupts_send_sgi(HF_IPI_INTID, target_cpu, true);
}

/**
 * IPI IRQ specific handling for the secure interrupt for each vCPU state:
 *   - WAITING: Trigger an SRI so the NWd can schedule to target vCPU to run.
 *   - RUNNING:
 *   - PREEMPTED/BLOCKED: Return and allow the normal secure interrupt handling
 *   to handle the interrupt as usual.
 * For all cases we must also mark the interrupt as complete from the
 * SPMC perspective.
 * Returns True if the IPI SGI has been handled.
 * False if further secure interrupt handling is required.
 */
bool hf_ipi_handle(struct vcpu_locked target_vcpu_locked)
{
	struct vcpu *target_vcpu = target_vcpu_locked.vcpu;

	switch (target_vcpu->state) {
	case VCPU_STATE_WAITING:
		plat_ffa_sri_trigger_not_delayed(target_vcpu->cpu);
		return true;
	case VCPU_STATE_RUNNING:
	case VCPU_STATE_BLOCKED:
	case VCPU_STATE_PREEMPTED:
		/*
		 * Let the normal secure interrupt handling handle the
		 * interrupt as usual.
		 */
		return false;
	default:
		dlog_error("Unexpected state: %u handling an IPI for [%x %u]",
			   target_vcpu->state, target_vcpu->vm->id,
			   vcpu_index(target_vcpu));
		return true;
	}
}