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Message-ID: <ZoKCd5t5yoMkee0a@lpieralisi>
Date: Mon, 1 Jul 2024 12:18:31 +0200
From: Lorenzo Pieralisi <lpieralisi@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org,
maz@...nel.org, anna-maria@...utronix.de, shawnguo@...nel.org,
s.hauer@...gutronix.de, festevam@...il.com, bhelgaas@...gle.com,
rdunlap@...radead.org, vidyas@...dia.com,
ilpo.jarvinen@...ux.intel.com, apatel@...tanamicro.com,
kevin.tian@...el.com, nipun.gupta@....com, den@...inux.co.jp,
andrew@...n.ch, gregory.clement@...tlin.com,
sebastian.hesselbarth@...il.com, gregkh@...uxfoundation.org,
rafael@...nel.org, alex.williamson@...hat.com, will@...nel.org,
lorenzo.pieralisi@....com, jgg@...lanox.com,
ammarfaizi2@...weeb.org, robin.murphy@....com, nm@...com,
kristo@...nel.org, vkoul@...nel.org, okaya@...nel.org,
agross@...nel.org, andersson@...nel.org, mark.rutland@....com,
shameerali.kolothum.thodi@...wei.com, yuzenghui@...wei.com,
shivamurthy.shastri@...utronix.de
Subject: Re: [patch V4 02/21] irqchip: Provide irq-msi-lib
On Sun, Jun 23, 2024 at 05:18:34PM +0200, Thomas Gleixner wrote:
[...]
> diff --git a/drivers/irqchip/irq-msi-lib.c b/drivers/irqchip/irq-msi-lib.c
> new file mode 100644
> index 000000000000..acbccf8f7f5b
> --- /dev/null
> +++ b/drivers/irqchip/irq-msi-lib.c
> @@ -0,0 +1,112 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +// Copyright (C) 2022 Linutronix GmbH
> +// Copyright (C) 2022 Intel
> +
> +#include <linux/export.h>
> +
> +#include "irq-msi-lib.h"
> +
> +/**
> + * msi_lib_init_dev_msi_info - Domain info setup for MSI domains
> + * @dev: The device for which the domain is created for
> + * @domain: The domain providing this callback
> + * @real_parent: The real parent domain of the domain to be initialized
> + * which might be a domain built on top of @domain or
> + * @domain itself
> + * @info: The domain info for the domain to be initialize
> + *
> + * This function is to be used for all types of MSI domains above the root
> + * parent domain and any intermediates. The topmost parent domain specific
> + * functionality is determined via @real_parent.
> + *
> + * All intermediate domains between the root and the device domain must
> + * have either msi_parent_ops.init_dev_msi_info = msi_parent_init_dev_msi_info
> + * or invoke it down the line.
> + */
> +bool msi_lib_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
> + struct irq_domain *real_parent,
> + struct msi_domain_info *info)
> +{
> + const struct msi_parent_ops *pops = real_parent->msi_parent_ops;
> +
> + /*
> + * MSI parent domain specific settings. For now there is only the
> + * root parent domain, e.g. NEXUS, acting as a MSI parent, but it is
> + * possible to stack MSI parents. See x86 vector -> irq remapping
> + */
> + if (domain->bus_token == pops->bus_select_token) {
> + if (WARN_ON_ONCE(domain != real_parent))
> + return false;
> + } else {
> + WARN_ON_ONCE(1);
> + return false;
> + }
> +
> + /* Parent ops available? */
> + if (WARN_ON_ONCE(!pops))
We have already dereferenced pops above, we should move this warning
before we dereference it (ie checked devmsi-arm-v4-2 too - branch same
comment applies there too).
Thanks
Lorenzo
> + return false;
> +
> + /* Is the target domain bus token supported? */
> + switch(info->bus_token) {
> + default:
> + /*
> + * This should never be reached. See
> + * msi_lib_irq_domain_select()
> + */
> + WARN_ON_ONCE(1);
> + return false;
> + }
> +
> + /*
> + * Mask out the domain specific MSI feature flags which are not
> + * supported by the real parent.
> + */
> + info->flags &= pops->supported_flags;
> + /* Enforce the required flags */
> + info->flags |= pops->required_flags;
> +
> + /* Chip updates for all child bus types */
> + if (!info->chip->irq_eoi)
> + info->chip->irq_eoi = irq_chip_eoi_parent;
> +
> + /*
> + * The device MSI domain can never have a set affinity callback. It
> + * always has to rely on the parent domain to handle affinity
> + * settings. The device MSI domain just has to write the resulting
> + * MSI message into the hardware which is the whole purpose of the
> + * device MSI domain aside of mask/unmask which is provided e.g. by
> + * PCI/MSI device domains.
> + */
> + info->chip->irq_set_affinity = msi_domain_set_affinity;
> + return true;
> +}
> +EXPORT_SYMBOL_GPL(msi_lib_init_dev_msi_info);
> +
> +/**
> + * msi_lib_irq_domain_select - Shared select function for NEXUS domains
> + * @d: Pointer to the irq domain on which select is invoked
> + * @fwspec: Firmware spec describing what is searched
> + * @bus_token: The bus token for which a matching irq domain is looked up
> + *
> + * Returns: %0 if @d is not what is being looked for
> + *
> + * %1 if @d is either the domain which is directly searched for or
> + * if @d is providing the parent MSI domain for the functionality
> + * requested with @bus_token.
> + */
> +int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
> + enum irq_domain_bus_token bus_token)
> +{
> + const struct msi_parent_ops *ops = d->msi_parent_ops;
> + u32 busmask = BIT(bus_token);
> +
> + if (fwspec->fwnode != d->fwnode || fwspec->param_count != 0)
> + return 0;
> +
> + /* Handle pure domain searches */
> + if (bus_token == ops->bus_select_token)
> + return 1;
> +
> + return ops && !!(ops->bus_select_mask & busmask);
> +}
> +EXPORT_SYMBOL_GPL(msi_lib_irq_domain_select);
> diff --git a/drivers/irqchip/irq-msi-lib.h b/drivers/irqchip/irq-msi-lib.h
> new file mode 100644
> index 000000000000..f0706cc28264
> --- /dev/null
> +++ b/drivers/irqchip/irq-msi-lib.h
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +// Copyright (C) 2022 Linutronix GmbH
> +// Copyright (C) 2022 Intel
> +
> +#ifndef _DRIVERS_IRQCHIP_IRQ_MSI_LIB_H
> +#define _DRIVERS_IRQCHIP_IRQ_MSI_LIB_H
> +
> +#include <linux/bits.h>
> +#include <linux/irqdomain.h>
> +#include <linux/msi.h>
> +
> +int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
> + enum irq_domain_bus_token bus_token);
> +
> +bool msi_lib_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
> + struct irq_domain *real_parent,
> + struct msi_domain_info *info);
> +
> +#endif /* _DRIVERS_IRQCHIP_IRQ_MSI_LIB_H */
> --
> 2.34.1
>
>
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