RE: [PATCH V8 2/8] ACPI: Add new IORT functions to support MSI domain handling

[Zheng, Lv]

Hi,

> From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of Lorenzo
> Pieralisi
> Subject: Re: [PATCH V8 2/8] ACPI: Add new IORT functions to support MSI domain handling
> 
> On Thu, Aug 11, 2016 at 12:06:32PM +0200, Tomasz Nowicki wrote:
> 
> [...]
> 
> > +/**
> > + * iort_register_domain_token() - register domain token and related ITS ID
> > + * to the list from where we can get it back later on.
> > + * @trans_id: ITS ID.
> > + * @fw_node: Domain token.
> > + *
> > + * Returns: 0 on success, -ENOMEM if no memory when allocating list element
> > + */
> > +int iort_register_domain_token(int trans_id, struct fwnode_handle *fw_node)
> > +{
> > +	struct iort_its_msi_chip *its_msi_chip;
> > +
> > +	its_msi_chip = kzalloc(sizeof(*its_msi_chip), GFP_KERNEL);
> 
> I spotted this while reworking my ARM SMMU series, this may sleep
> and that's no good given that we call it within the acpi_probe_lock.
> 
> Same goes for irq_domain_alloc_fwnode() (that we call in
> gic_v2_acpi_init()), we have got to fix this usage, I will see with
> Marc what's the best way to do it.

If we can ensure that all table device probe entries are created during link stage or early stage.
I think you can safely unlock probe lock before invoking acpi_table_parse() in __acpi_probe_device_table().

Thanks
Lv

> 
> Lorenzo
> 
> > +	if (!its_msi_chip)
> > +		return -ENOMEM;
> > +
> > +	its_msi_chip->fw_node = fw_node;
> > +	its_msi_chip->translation_id = trans_id;
> > +
> > +	spin_lock(&iort_msi_chip_lock);
> > +	list_add(&its_msi_chip->list, &iort_msi_chip_list);
> > +	spin_unlock(&iort_msi_chip_lock);
> > +
> > +	return 0;
> > +}
> > +
> > +/**
> > + * iort_deregister_domain_token() - Deregister domain token based on ITS ID
> > + * @trans_id: ITS ID.
> > + *
> > + * Returns: none.
> > + */
> > +void iort_deregister_domain_token(int trans_id)
> > +{
> > +	struct iort_its_msi_chip *its_msi_chip, *t;
> > +
> > +	spin_lock(&iort_msi_chip_lock);
> > +	list_for_each_entry_safe(its_msi_chip, t, &iort_msi_chip_list, list) {
> > +		if (its_msi_chip->translation_id == trans_id) {
> > +			list_del(&its_msi_chip->list);
> > +			kfree(its_msi_chip);
> > +			break;
> > +		}
> > +	}
> > +	spin_unlock(&iort_msi_chip_lock);
> > +}
> > +
> > +/**
> > + * iort_find_domain_token() - Find domain token based on given ITS ID
> > + * @trans_id: ITS ID.
> > + *
> > + * Returns: domain token when find on the list, NULL otherwise
> > + */
> > +struct fwnode_handle *iort_find_domain_token(int trans_id)
> > +{
> > +	struct fwnode_handle *fw_node = NULL;
> > +	struct iort_its_msi_chip *its_msi_chip;
> > +
> > +	spin_lock(&iort_msi_chip_lock);
> > +	list_for_each_entry(its_msi_chip, &iort_msi_chip_list, list) {
> > +		if (its_msi_chip->translation_id == trans_id) {
> > +			fw_node = its_msi_chip->fw_node;
> > +			break;
> > +		}
> > +	}
> > +	spin_unlock(&iort_msi_chip_lock);
> > +
> > +	return fw_node;
> > +}
> > +
> >  static struct acpi_iort_node *
> >  iort_scan_node(enum acpi_iort_node_type type,
> >  	       iort_find_node_callback callback, void *context)
> > @@ -206,6 +285,96 @@ iort_find_dev_node(struct device *dev)
> >  			      iort_match_node_callback, &pbus->dev);
> >  }
> >
> > +/**
> > + * iort_msi_map_rid() - Map a MSI requester ID for a device
> > + * @dev: The device for which the mapping is to be done.
> > + * @req_id: The device requester ID.
> > + *
> > + * Returns: mapped MSI RID on success, input requester ID otherwise
> > + */
> > +u32 iort_msi_map_rid(struct device *dev, u32 req_id)
> > +{
> > +	struct acpi_iort_node *node;
> > +	u32 dev_id;
> > +
> > +	if (!iort_table)
> > +		return req_id;
> > +
> > +	node = iort_find_dev_node(dev);
> > +	if (!node) {
> > +		dev_err(dev, "can't find related IORT node\n");
> > +		return req_id;
> > +	}
> > +
> > +	iort_node_map_rid(node, req_id, &dev_id, ACPI_IORT_NODE_ITS_GROUP);
> > +	return dev_id;
> > +}
> > +
> > +/**
> > + * iort_dev_find_its_id() - Find the ITS identifier for a device
> > + * @dev: The device.
> > + * @idx: Index of the ITS identifier list.
> > + * @its_id: ITS identifier.
> > + *
> > + * Returns: 0 on success, appropriate error value otherwise
> > + */
> > +static int
> > +iort_dev_find_its_id(struct device *dev, u32 req_id, unsigned int idx,
> > +		     int *its_id)
> > +{
> > +	struct acpi_iort_its_group *its;
> > +	struct acpi_iort_node *node;
> > +
> > +	node = iort_find_dev_node(dev);
> > +	if (!node) {
> > +		dev_err(dev, "can't find related IORT node\n");
> > +		return -ENXIO;
> > +	}
> > +
> > +	node = iort_node_map_rid(node, req_id, NULL, ACPI_IORT_NODE_ITS_GROUP);
> > +	if (!node) {
> > +		dev_err(dev, "can't find related ITS node\n");
> > +		return -ENXIO;
> > +	}
> > +
> > +	/* Move to ITS specific data */
> > +	its = (struct acpi_iort_its_group *)node->node_data;
> > +	if (idx > its->its_count) {
> > +		dev_err(dev, "requested ITS ID index [%d] is greater than available [%d]\n",
> > +			idx, its->its_count);
> > +		return -ENXIO;
> > +	}
> > +
> > +	*its_id = its->identifiers[idx];
> > +	return 0;
> > +}
> > +
> > +/**
> > + * iort_get_device_domain() - Find MSI domain related to a device
> > + * @dev: The device.
> > + * @req_id: Requester ID for the device.
> > + *
> > + * Returns: the MSI domain for this device, NULL otherwise
> > + */
> > +struct irq_domain *
> > +iort_get_device_domain(struct device *dev, u32 req_id)
> > +{
> > +	static struct fwnode_handle *handle;
> > +	int its_id;
> > +
> > +	if (!iort_table)
> > +		return NULL;
> > +
> > +	if (iort_dev_find_its_id(dev, req_id, 0, &its_id))
> > +		return NULL;
> > +
> > +	handle = iort_find_domain_token(its_id);
> > +	if (!handle)
> > +		return NULL;
> > +
> > +	return irq_find_matching_fwnode(handle, DOMAIN_BUS_PCI_MSI);
> > +}
> > +
> >  void __init iort_table_detect(void)
> >  {
> >  	acpi_status status;
> > diff --git a/include/linux/iort.h b/include/linux/iort.h
> > index cde6809..d7daba1 100644
> > --- a/include/linux/iort.h
> > +++ b/include/linux/iort.h
> > @@ -20,11 +20,22 @@
> >  #define __IORT_H__
> >
> >  #include <linux/acpi.h>
> > +#include <linux/fwnode.h>
> > +#include <linux/irqdomain.h>
> >
> > +int iort_register_domain_token(int trans_id, struct fwnode_handle *fw_node);
> > +void iort_deregister_domain_token(int trans_id);
> > +struct fwnode_handle *iort_find_domain_token(int trans_id);
> >  #ifdef CONFIG_IORT_TABLE
> >  void iort_table_detect(void);
> > +u32 iort_msi_map_rid(struct device *dev, u32 req_id);
> > +struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id);
> >  #else
> >  static inline void iort_table_detect(void) { }
> > +static inline u32 iort_msi_map_rid(struct device *dev, u32 req_id)
> > +{ return req_id; }
> > +static inline struct irq_domain *
> > +iort_get_device_domain(struct device *dev, u32 req_id) { return NULL; }
> >  #endif
> >
> >  #endif /* __IORT_H__ */
> > --
> > 1.9.1
> >
> --
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