Re: [PATCH RFC 04/15] drivers/base: Add support for a new IMS irq domain

[Thomas Gleixner]

Dave Jiang <dave.jiang@xxxxxxxxx> writes:
> From: Megha Dey <megha.dey@xxxxxxxxxxxxxxx>
>
> Add support for the creation of a new IMS irq domain. It creates a new
> irq chip associated with the IMS domain and adds the necessary domain
> operations to it.

And how is a X86 specific thingy related to drivers/base?

> diff --git a/drivers/base/ims-msi.c b/drivers/base/ims-msi.c

This sits in drivers base because IMS is architecture independent, right?

> new file mode 100644
> index 000000000000..738f6d153155
> --- /dev/null
> +++ b/drivers/base/ims-msi.c
> @@ -0,0 +1,100 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Support for Device Specific IMS interrupts.
> + *
> + * Copyright  2019 Intel Corporation.
> + *
> + * Author: Megha Dey <megha.dey@xxxxxxxxx>
> + */
> +
> +#include <linux/dmar.h>
> +#include <linux/irq.h>
> +#include <linux/mdev.h>
> +#include <linux/pci.h>
> +
> +/*
> + * Determine if a dev is mdev or not. Return NULL if not mdev device.
> + * Return mdev's parent dev if success.
> + */
> +static inline struct device *mdev_to_parent(struct device *dev)
> +{
> +	struct device *ret = NULL;
> +	struct device *(*fn)(struct device *dev);
> +	struct bus_type *bus = symbol_get(mdev_bus_type);

symbol_get()?

> +
> +	if (bus && dev->bus == bus) {
> +		fn = symbol_get(mdev_dev_to_parent_dev);

What's wrong with simple function calls?

> +		ret = fn(dev);
> +		symbol_put(mdev_dev_to_parent_dev);
> +		symbol_put(mdev_bus_type);
> +	}
> +
> +	return ret;
> +}
> +
> +static irq_hw_number_t dev_ims_get_hwirq(struct msi_domain_info *info,
> +					 msi_alloc_info_t *arg)
> +{
> +	return arg->ims_hwirq;
> +}
> +
> +static int dev_ims_prepare(struct irq_domain *domain, struct device *dev,
> +			   int nvec, msi_alloc_info_t *arg)
> +{
> +	if (dev_is_mdev(dev))
> +		dev = mdev_to_parent(dev);

This makes absolutely no sense. Somewhere you claimed that this is
solely for mdev. Now this interface takes both a regular device and mdev.

Lack of explanation seems to be a common scheme here.

> +	init_irq_alloc_info(arg, NULL);
> +	arg->dev = dev;
> +	arg->type = X86_IRQ_ALLOC_TYPE_IMS;
> +
> +	return 0;
> +}
> +
> +static void dev_ims_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
> +{
> +	arg->ims_hwirq = platform_msi_calc_hwirq(desc);
> +}
> +
> +static struct msi_domain_ops dev_ims_domain_ops = {
> +	.get_hwirq	= dev_ims_get_hwirq,
> +	.msi_prepare	= dev_ims_prepare,
> +	.set_desc	= dev_ims_set_desc,
> +};
> +
> +static struct irq_chip dev_ims_ir_controller = {
> +	.name			= "IR-DEV-IMS",
> +	.irq_ack		= irq_chip_ack_parent,
> +	.irq_retrigger		= irq_chip_retrigger_hierarchy,
> +	.irq_set_vcpu_affinity	= irq_chip_set_vcpu_affinity_parent,
> +	.flags			= IRQCHIP_SKIP_SET_WAKE,
> +	.irq_write_msi_msg	= platform_msi_write_msg,
> +};
> +
> +static struct msi_domain_info ims_ir_domain_info = {
> +	.flags		= MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS,
> +	.ops		= &dev_ims_domain_ops,
> +	.chip		= &dev_ims_ir_controller,
> +	.handler	= handle_edge_irq,
> +	.handler_name	= "edge",
> +};
> +
> +struct irq_domain *arch_create_ims_irq_domain(struct irq_domain *parent,
> +					      const char *name)

arch_create_ ???? In drivers/base ??? 

> +{
> +	struct fwnode_handle *fn;
> +	struct irq_domain *domain;
> +
> +	fn = irq_domain_alloc_named_fwnode(name);
> +	if (!fn)
> +		return NULL;
> +
> +	domain = msi_create_irq_domain(fn, &ims_ir_domain_info, parent);
> +	if (!domain)
> +		return NULL;
> +
> +	irq_domain_update_bus_token(domain, DOMAIN_BUS_PLATFORM_MSI);
> +	irq_domain_free_fwnode(fn);
> +
> +	return domain;
> +}
> diff --git a/drivers/base/platform-msi.c b/drivers/base/platform-msi.c
> index 2696aa75983b..59160e8cbfb1 100644
> --- a/drivers/base/platform-msi.c
> +++ b/drivers/base/platform-msi.c
> @@ -31,12 +31,11 @@ struct platform_msi_priv_data {
>  /* The devid allocator */
>  static DEFINE_IDA(platform_msi_devid_ida);
>  
> -#ifdef GENERIC_MSI_DOMAIN_OPS
>  /*
>   * Convert an msi_desc to a globaly unique identifier (per-device
>   * devid + msi_desc position in the msi_list).
>   */
> -static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
> +irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
>  {
>  	u32 devid;
>  
> @@ -45,6 +44,7 @@ static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
>  	return (devid << (32 - DEV_ID_SHIFT)) | desc->platform.msi_index;
>  }
>  
> +#ifdef GENERIC_MSI_DOMAIN_OPS
>  static void platform_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
>  {
>  	arg->desc = desc;
> @@ -76,7 +76,7 @@ static void platform_msi_update_dom_ops(struct msi_domain_info *info)
>  		ops->set_desc = platform_msi_set_desc;
>  }
>  
> -static void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
> +void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
>  {
>  	struct msi_desc *desc = irq_data_get_msi_desc(data);
>  	struct platform_msi_priv_data *priv_data;
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index b558d4cfd082..cecc6a6bdbef 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -33,6 +33,12 @@ struct device *mdev_parent_dev(struct mdev_device *mdev)
>  }
>  EXPORT_SYMBOL(mdev_parent_dev);
>  
> +struct device *mdev_dev_to_parent_dev(struct device *dev)
> +{
> +	return to_mdev_device(dev)->parent->dev;
> +}
> +EXPORT_SYMBOL(mdev_dev_to_parent_dev);

And this needs to be EXPORT_SYMBOL because this is designed to support
non GPL drivers from the very beginning, right? Ditto for the other
exports in this file.

> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
> index 7d922950caaf..c21f1305a76b 100644
> --- a/drivers/vfio/mdev/mdev_private.h
> +++ b/drivers/vfio/mdev/mdev_private.h
> @@ -36,7 +36,6 @@ struct mdev_device {
>  };
>  
>  #define to_mdev_device(dev)	container_of(dev, struct mdev_device, dev)
> -#define dev_is_mdev(d)		((d)->bus == &mdev_bus_type)

Moving stuff around 3 patches later makes tons of sense.
  
Thanks,

        tglx