irqdomain.c

// SPDX-License-Identifier: GPL-2.0

/*
 * Irqdomain for Linux to run as the root partition on Microsoft Hypervisor.
 *
 * Authors:
 *  Sunil Muthuswamy <[email protected]>
 *  Wei Liu <[email protected]>
 */

#include <linux/pci.h>
#include <linux/irq.h>
#include <linux/export.h>
#include <linux/irqchip/irq-msi-lib.h>
#include <asm/mshyperv.h>

static int hv_map_interrupt(union hv_device_id device_id, bool level,
		int cpu, int vector, struct hv_interrupt_entry *entry)
{
	struct hv_input_map_device_interrupt *input;
	struct hv_output_map_device_interrupt *output;
	struct hv_device_interrupt_descriptor *intr_desc;
	unsigned long flags;
	u64 status;
	int nr_bank, var_size;

	local_irq_save(flags);

	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
	output = *this_cpu_ptr(hyperv_pcpu_output_arg);

	intr_desc = &input->interrupt_descriptor;
	memset(input, 0, sizeof(*input));
	input->partition_id = hv_current_partition_id;
	input->device_id = device_id.as_uint64;
	intr_desc->interrupt_type = HV_X64_INTERRUPT_TYPE_FIXED;
	intr_desc->vector_count = 1;
	intr_desc->target.vector = vector;

	if (level)
		intr_desc->trigger_mode = HV_INTERRUPT_TRIGGER_MODE_LEVEL;
	else
		intr_desc->trigger_mode = HV_INTERRUPT_TRIGGER_MODE_EDGE;

	intr_desc->target.vp_set.valid_bank_mask = 0;
	intr_desc->target.vp_set.format = HV_GENERIC_SET_SPARSE_4K;
	nr_bank = cpumask_to_vpset(&(intr_desc->target.vp_set), cpumask_of(cpu));
	if (nr_bank < 0) {
		local_irq_restore(flags);
		pr_err("%s: unable to generate VP set\n", __func__);
		return -EINVAL;
	}
	intr_desc->target.flags = HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET;

	/*
	 * var-sized hypercall, var-size starts after vp_mask (thus
	 * vp_set.format does not count, but vp_set.valid_bank_mask
	 * does).
	 */
	var_size = nr_bank + 1;

	status = hv_do_rep_hypercall(HVCALL_MAP_DEVICE_INTERRUPT, 0, var_size,
			input, output);
	*entry = output->interrupt_entry;

	local_irq_restore(flags);

	if (!hv_result_success(status))
		hv_status_err(status, "\n");

	return hv_result_to_errno(status);
}

static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *old_entry)
{
	unsigned long flags;
	struct hv_input_unmap_device_interrupt *input;
	struct hv_interrupt_entry *intr_entry;
	u64 status;

	local_irq_save(flags);
	input = *this_cpu_ptr(hyperv_pcpu_input_arg);

	memset(input, 0, sizeof(*input));
	intr_entry = &input->interrupt_entry;
	input->partition_id = hv_current_partition_id;
	input->device_id = id;
	*intr_entry = *old_entry;

	status = hv_do_hypercall(HVCALL_UNMAP_DEVICE_INTERRUPT, input, NULL);
	local_irq_restore(flags);

	if (!hv_result_success(status))
		hv_status_err(status, "\n");

	return hv_result_to_errno(status);
}

#ifdef CONFIG_PCI_MSI
struct rid_data {
	struct pci_dev *bridge;
	u32 rid;
};

static int get_rid_cb(struct pci_dev *pdev, u16 alias, void *data)
{
	struct rid_data *rd = data;
	u8 bus = PCI_BUS_NUM(rd->rid);

	if (pdev->bus->number != bus || PCI_BUS_NUM(alias) != bus) {
		rd->bridge = pdev;
		rd->rid = alias;
	}

	return 0;
}

static union hv_device_id hv_build_pci_dev_id(struct pci_dev *dev)
{
	union hv_device_id dev_id;
	struct rid_data data = {
		.bridge = NULL,
		.rid = PCI_DEVID(dev->bus->number, dev->devfn)
	};

	pci_for_each_dma_alias(dev, get_rid_cb, &data);

	dev_id.as_uint64 = 0;
	dev_id.device_type = HV_DEVICE_TYPE_PCI;
	dev_id.pci.segment = pci_domain_nr(dev->bus);

	dev_id.pci.bdf.bus = PCI_BUS_NUM(data.rid);
	dev_id.pci.bdf.device = PCI_SLOT(data.rid);
	dev_id.pci.bdf.function = PCI_FUNC(data.rid);
	dev_id.pci.source_shadow = HV_SOURCE_SHADOW_NONE;

	if (data.bridge) {
		int pos;

		/*
		 * Microsoft Hypervisor requires a bus range when the bridge is
		 * running in PCI-X mode.
		 *
		 * To distinguish conventional vs PCI-X bridge, we can check
		 * the bridge's PCI-X Secondary Status Register, Secondary Bus
		 * Mode and Frequency bits. See PCI Express to PCI/PCI-X Bridge
		 * Specification Revision 1.0 5.2.2.1.3.
		 *
		 * Value zero means it is in conventional mode, otherwise it is
		 * in PCI-X mode.
		 */

		pos = pci_find_capability(data.bridge, PCI_CAP_ID_PCIX);
		if (pos) {
			u16 status;

			pci_read_config_word(data.bridge, pos +
					PCI_X_BRIDGE_SSTATUS, &status);

			if (status & PCI_X_SSTATUS_FREQ) {
				/* Non-zero, PCI-X mode */
				u8 sec_bus, sub_bus;

				dev_id.pci.source_shadow = HV_SOURCE_SHADOW_BRIDGE_BUS_RANGE;

				pci_read_config_byte(data.bridge, PCI_SECONDARY_BUS, &sec_bus);
				dev_id.pci.shadow_bus_range.secondary_bus = sec_bus;
				pci_read_config_byte(data.bridge, PCI_SUBORDINATE_BUS, &sub_bus);
				dev_id.pci.shadow_bus_range.subordinate_bus = sub_bus;
			}
		}
	}

	return dev_id;
}

/**
 * hv_map_msi_interrupt() - "Map" the MSI IRQ in the hypervisor.
 * @data:      Describes the IRQ
 * @out_entry: Hypervisor (MSI) interrupt entry (can be NULL)
 *
 * Map the IRQ in the hypervisor by issuing a MAP_DEVICE_INTERRUPT hypercall.
 *
 * Return: 0 on success, -errno on failure
 */
int hv_map_msi_interrupt(struct irq_data *data,
			 struct hv_interrupt_entry *out_entry)
{
	struct irq_cfg *cfg = irqd_cfg(data);
	struct hv_interrupt_entry dummy;
	union hv_device_id device_id;
	struct msi_desc *msidesc;
	struct pci_dev *dev;
	int cpu;

	msidesc = irq_data_get_msi_desc(data);
	dev = msi_desc_to_pci_dev(msidesc);
	device_id = hv_build_pci_dev_id(dev);
	cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));

	return hv_map_interrupt(device_id, false, cpu, cfg->vector,
				out_entry ? out_entry : &dummy);
}
EXPORT_SYMBOL_GPL(hv_map_msi_interrupt);

static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi_msg *msg)
{
	/* High address is always 0 */
	msg->address_hi = 0;
	msg->address_lo = entry->msi_entry.address.as_uint32;
	msg->data = entry->msi_entry.data.as_uint32;
}

static int hv_unmap_msi_interrupt(struct pci_dev *dev, struct hv_interrupt_entry *old_entry);
static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
	struct hv_interrupt_entry *stored_entry;
	struct irq_cfg *cfg = irqd_cfg(data);
	struct msi_desc *msidesc;
	struct pci_dev *dev;
	int ret;

	msidesc = irq_data_get_msi_desc(data);
	dev = msi_desc_to_pci_dev(msidesc);

	if (!cfg) {
		pr_debug("%s: cfg is NULL", __func__);
		return;
	}

	if (data->chip_data) {
		/*
		 * This interrupt is already mapped. Let's unmap first.
		 *
		 * We don't use retarget interrupt hypercalls here because
		 * Microsoft Hypervisor doesn't allow root to change the vector
		 * or specify VPs outside of the set that is initially used
		 * during mapping.
		 */
		stored_entry = data->chip_data;
		data->chip_data = NULL;

		ret = hv_unmap_msi_interrupt(dev, stored_entry);

		kfree(stored_entry);

		if (ret)
			return;
	}

	stored_entry = kzalloc(sizeof(*stored_entry), GFP_ATOMIC);
	if (!stored_entry) {
		pr_debug("%s: failed to allocate chip data\n", __func__);
		return;
	}

	ret = hv_map_msi_interrupt(data, stored_entry);
	if (ret) {
		kfree(stored_entry);
		return;
	}

	data->chip_data = stored_entry;
	entry_to_msi_msg(data->chip_data, msg);

	return;
}

static int hv_unmap_msi_interrupt(struct pci_dev *dev, struct hv_interrupt_entry *old_entry)
{
	return hv_unmap_interrupt(hv_build_pci_dev_id(dev).as_uint64, old_entry);
}

static void hv_teardown_msi_irq(struct pci_dev *dev, struct irq_data *irqd)
{
	struct hv_interrupt_entry old_entry;
	struct msi_msg msg;

	if (!irqd->chip_data) {
		pr_debug("%s: no chip data\n!", __func__);
		return;
	}

	old_entry = *(struct hv_interrupt_entry *)irqd->chip_data;
	entry_to_msi_msg(&old_entry, &msg);

	kfree(irqd->chip_data);
	irqd->chip_data = NULL;

	(void)hv_unmap_msi_interrupt(dev, &old_entry);
}

/*
 * IRQ Chip for MSI PCI/PCI-X/PCI-Express Devices,
 * which implement the MSI or MSI-X Capability Structure.
 */
static struct irq_chip hv_pci_msi_controller = {
	.name			= "HV-PCI-MSI",
	.irq_ack		= irq_chip_ack_parent,
	.irq_compose_msi_msg	= hv_irq_compose_msi_msg,
	.irq_set_affinity	= irq_chip_set_affinity_parent,
};

static bool hv_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
				 struct irq_domain *real_parent, struct msi_domain_info *info)
{
	struct irq_chip *chip = info->chip;

	if (!msi_lib_init_dev_msi_info(dev, domain, real_parent, info))
		return false;

	chip->flags |= IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MOVE_DEFERRED;

	info->ops->msi_prepare = pci_msi_prepare;

	return true;
}

#define HV_MSI_FLAGS_SUPPORTED	(MSI_GENERIC_FLAGS_MASK | MSI_FLAG_PCI_MSIX)
#define HV_MSI_FLAGS_REQUIRED	(MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS)

static struct msi_parent_ops hv_msi_parent_ops = {
	.supported_flags	= HV_MSI_FLAGS_SUPPORTED,
	.required_flags		= HV_MSI_FLAGS_REQUIRED,
	.bus_select_token	= DOMAIN_BUS_NEXUS,
	.bus_select_mask	= MATCH_PCI_MSI,
	.chip_flags		= MSI_CHIP_FLAG_SET_ACK,
	.prefix			= "HV-",
	.init_dev_msi_info	= hv_init_dev_msi_info,
};

static int hv_msi_domain_alloc(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs,
			       void *arg)
{
	/*
	 * TODO: The allocation bits of hv_irq_compose_msi_msg(), i.e. everything except
	 * entry_to_msi_msg() should be in here.
	 */

	int ret;

	ret = irq_domain_alloc_irqs_parent(d, virq, nr_irqs, arg);
	if (ret)
		return ret;

	for (int i = 0; i < nr_irqs; ++i) {
		irq_domain_set_info(d, virq + i, 0, &hv_pci_msi_controller, NULL,
				    handle_edge_irq, NULL, "edge");
	}
	return 0;
}

static void hv_msi_domain_free(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs)
{
	for (int i = 0; i < nr_irqs; ++i) {
		struct irq_data *irqd = irq_domain_get_irq_data(d, virq);
		struct msi_desc *desc;

		desc = irq_data_get_msi_desc(irqd);
		if (!desc || !desc->irq || WARN_ON_ONCE(!dev_is_pci(desc->dev)))
			continue;

		hv_teardown_msi_irq(to_pci_dev(desc->dev), irqd);
	}
	irq_domain_free_irqs_top(d, virq, nr_irqs);
}

static const struct irq_domain_ops hv_msi_domain_ops = {
	.select	= msi_lib_irq_domain_select,
	.alloc	= hv_msi_domain_alloc,
	.free	= hv_msi_domain_free,
};

struct irq_domain * __init hv_create_pci_msi_domain(void)
{
	struct irq_domain *d = NULL;

	struct irq_domain_info info = {
		.fwnode		= irq_domain_alloc_named_fwnode("HV-PCI-MSI"),
		.ops		= &hv_msi_domain_ops,
		.parent		= x86_vector_domain,
	};

	if (info.fwnode)
		d = msi_create_parent_irq_domain(&info, &hv_msi_parent_ops);

	/* No point in going further if we can't get an irq domain */
	BUG_ON(!d);

	return d;
}

#endif /* CONFIG_PCI_MSI */

int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry)
{
	union hv_device_id device_id;

	device_id.as_uint64 = 0;
	device_id.device_type = HV_DEVICE_TYPE_IOAPIC;
	device_id.ioapic.ioapic_id = (u8)ioapic_id;

	return hv_unmap_interrupt(device_id.as_uint64, entry);
}
EXPORT_SYMBOL_GPL(hv_unmap_ioapic_interrupt);

int hv_map_ioapic_interrupt(int ioapic_id, bool level, int cpu, int vector,
		struct hv_interrupt_entry *entry)
{
	union hv_device_id device_id;

	device_id.as_uint64 = 0;
	device_id.device_type = HV_DEVICE_TYPE_IOAPIC;
	device_id.ioapic.ioapic_id = (u8)ioapic_id;

	return hv_map_interrupt(device_id, level, cpu, vector, entry);
}
EXPORT_SYMBOL_GPL(hv_map_ioapic_interrupt);