drivers/vfio/cdx/intr.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
 */

#include <linux/vfio.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/eventfd.h>
#include <linux/msi.h>
#include <linux/interrupt.h>

#include "linux/cdx/cdx_bus.h"
#include "private.h"

static irqreturn_t vfio_cdx_msihandler(int irq_no, void *arg)
{
	struct eventfd_ctx *trigger = arg;

	eventfd_signal(trigger);
	return IRQ_HANDLED;
}

static int vfio_cdx_msi_enable(struct vfio_cdx_device *vdev, int nvec)
{
	struct cdx_device *cdx_dev = to_cdx_device(vdev->vdev.dev);
	struct device *dev = vdev->vdev.dev;
	int msi_idx, ret;

	vdev->cdx_irqs = kcalloc(nvec, sizeof(struct vfio_cdx_irq), GFP_KERNEL);
	if (!vdev->cdx_irqs)
		return -ENOMEM;

	ret = cdx_enable_msi(cdx_dev);
	if (ret) {
		kfree(vdev->cdx_irqs);
		return ret;
	}

	/* Allocate cdx MSIs */
	ret = msi_domain_alloc_irqs(dev, MSI_DEFAULT_DOMAIN, nvec);
	if (ret) {
		cdx_disable_msi(cdx_dev);
		kfree(vdev->cdx_irqs);
		return ret;
	}

	for (msi_idx = 0; msi_idx < nvec; msi_idx++)
		vdev->cdx_irqs[msi_idx].irq_no = msi_get_virq(dev, msi_idx);

	vdev->msi_count = nvec;
	vdev->config_msi = 1;

	return 0;
}

static int vfio_cdx_msi_set_vector_signal(struct vfio_cdx_device *vdev,
					  int vector, int fd)
{
	struct eventfd_ctx *trigger;
	int irq_no, ret;

	if (vector < 0 || vector >= vdev->msi_count)
		return -EINVAL;

	irq_no = vdev->cdx_irqs[vector].irq_no;

	if (vdev->cdx_irqs[vector].trigger) {
		free_irq(irq_no, vdev->cdx_irqs[vector].trigger);
		kfree(vdev->cdx_irqs[vector].name);
		eventfd_ctx_put(vdev->cdx_irqs[vector].trigger);
		vdev->cdx_irqs[vector].trigger = NULL;
	}

	if (fd < 0)
		return 0;

	vdev->cdx_irqs[vector].name = kasprintf(GFP_KERNEL, "vfio-msi[%d](%s)",
						vector, dev_name(vdev->vdev.dev));
	if (!vdev->cdx_irqs[vector].name)
		return -ENOMEM;

	trigger = eventfd_ctx_fdget(fd);
	if (IS_ERR(trigger)) {
		kfree(vdev->cdx_irqs[vector].name);
		return PTR_ERR(trigger);
	}

	ret = request_irq(irq_no, vfio_cdx_msihandler, 0,
			  vdev->cdx_irqs[vector].name, trigger);
	if (ret) {
		kfree(vdev->cdx_irqs[vector].name);
		eventfd_ctx_put(trigger);
		return ret;
	}

	vdev->cdx_irqs[vector].trigger = trigger;

	return 0;
}

static int vfio_cdx_msi_set_block(struct vfio_cdx_device *vdev,
				  unsigned int start, unsigned int count,
				  int32_t *fds)
{
	int i, j, ret = 0;

	if (start >= vdev->msi_count || start + count > vdev->msi_count)
		return -EINVAL;

	for (i = 0, j = start; i < count && !ret; i++, j++) {
		int fd = fds ? fds[i] : -1;

		ret = vfio_cdx_msi_set_vector_signal(vdev, j, fd);
	}

	if (ret) {
		for (--j; j >= (int)start; j--)
			vfio_cdx_msi_set_vector_signal(vdev, j, -1);
	}

	return ret;
}

static void vfio_cdx_msi_disable(struct vfio_cdx_device *vdev)
{
	struct cdx_device *cdx_dev = to_cdx_device(vdev->vdev.dev);
	struct device *dev = vdev->vdev.dev;

	vfio_cdx_msi_set_block(vdev, 0, vdev->msi_count, NULL);

	if (!vdev->config_msi)
		return;

	msi_domain_free_irqs_all(dev, MSI_DEFAULT_DOMAIN);
	cdx_disable_msi(cdx_dev);
	kfree(vdev->cdx_irqs);

	vdev->cdx_irqs = NULL;
	vdev->msi_count = 0;
	vdev->config_msi = 0;
}

static int vfio_cdx_set_msi_trigger(struct vfio_cdx_device *vdev,
				    unsigned int index, unsigned int start,
				    unsigned int count, u32 flags,
				    void *data)
{
	struct cdx_device *cdx_dev = to_cdx_device(vdev->vdev.dev);
	int i;

	if (start + count > cdx_dev->num_msi)
		return -EINVAL;

	if (!count && (flags & VFIO_IRQ_SET_DATA_NONE)) {
		vfio_cdx_msi_disable(vdev);
		return 0;
	}

	if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
		s32 *fds = data;
		int ret;

		if (vdev->config_msi)
			return vfio_cdx_msi_set_block(vdev, start, count,
						  fds);
		ret = vfio_cdx_msi_enable(vdev, cdx_dev->num_msi);
		if (ret)
			return ret;

		ret = vfio_cdx_msi_set_block(vdev, start, count, fds);
		if (ret)
			vfio_cdx_msi_disable(vdev);

		return ret;
	}

	for (i = start; i < start + count; i++) {
		if (!vdev->cdx_irqs[i].trigger)
			continue;
		if (flags & VFIO_IRQ_SET_DATA_NONE) {
			eventfd_signal(vdev->cdx_irqs[i].trigger);
		} else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
			u8 *bools = data;

			if (bools[i - start])
				eventfd_signal(vdev->cdx_irqs[i].trigger);
		}
	}

	return 0;
}

int vfio_cdx_set_irqs_ioctl(struct vfio_cdx_device *vdev,
			    u32 flags, unsigned int index,
			    unsigned int start, unsigned int count,
			    void *data)
{
	if (flags & VFIO_IRQ_SET_ACTION_TRIGGER)
		return vfio_cdx_set_msi_trigger(vdev, index, start,
			  count, flags, data);
	else
		return -EINVAL;
}

/* Free All IRQs for the given device */
void vfio_cdx_irqs_cleanup(struct vfio_cdx_device *vdev)
{
	/*
	 * Device does not support any interrupt or the interrupts
	 * were not configured
	 */
	if (!vdev->cdx_irqs)
		return;

	vfio_cdx_set_msi_trigger(vdev, 0, 0, 0, VFIO_IRQ_SET_DATA_NONE, NULL);
}