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

Thomas Gleixner
2020-04-25T21:39:12Z

Dave Jiang <dave.jiang@intel.com> writes:
> From: Megha Dey <megha.dey@linux.intel.com>
>
> 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@intel.com>
> + */
> +
> +#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