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Date:   Fri, 13 Sep 2019 16:07:04 -0600
From:   Alex Williamson <alex.williamson@redhat.com>
To:     Megha Dey <megha.dey@linux.intel.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-pci@vger.kernel.org, maz@kernel.org, bhelgaas@google.com,
        rafael@kernel.org, gregkh@linuxfoundation.org, tglx@linutronix.de,
        hpa@zytor.com, jgg@mellanox.com, ashok.raj@intel.com,
        megha.dey@intel.com, jacob.jun.pan@intel.com,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Sanjay Kumar <sanjay.k.kumar@intel.com>
Subject: Re: [RFC V1 3/7] x86/ims: Add support for a new IMS irq domain
Message-ID: <20190913160704.03d4df6c@x1.home>
In-Reply-To: <1568338328-22458-4-git-send-email-megha.dey@linux.intel.com>
References: <1568338328-22458-1-git-send-email-megha.dey@linux.intel.com>
        <1568338328-22458-4-git-send-email-megha.dey@linux.intel.com>
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On Thu, 12 Sep 2019 18:32:04 -0700
Megha Dey <megha.dey@linux.intel.com> wrote:

> This patch adds 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.
> 
> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
> Signed-off-by: Megha Dey <megha.dey@linux.intel.com>
> ---
>  arch/x86/include/asm/msi.h       |  4 ++
>  arch/x86/kernel/apic/Makefile    |  1 +
>  arch/x86/kernel/apic/ims.c       | 93 ++++++++++++++++++++++++++++++++++++++++
>  arch/x86/kernel/apic/msi.c       |  4 +-
>  drivers/vfio/mdev/mdev_core.c    |  6 +++
>  drivers/vfio/mdev/mdev_private.h |  1 -
>  include/linux/mdev.h             |  2 +
>  7 files changed, 108 insertions(+), 3 deletions(-)
>  create mode 100644 arch/x86/kernel/apic/ims.c
> 
> diff --git a/arch/x86/include/asm/msi.h b/arch/x86/include/asm/msi.h
> index 25ddd09..51f9d25 100644
> --- a/arch/x86/include/asm/msi.h
> +++ b/arch/x86/include/asm/msi.h
> @@ -11,4 +11,8 @@ int pci_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
>  
>  void pci_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc);
>  
> +struct msi_domain_info;
> +
> +irq_hw_number_t msi_get_hwirq(struct msi_domain_info *info,
> +						msi_alloc_info_t *arg);
>  #endif /* _ASM_X86_MSI_H */
> diff --git a/arch/x86/kernel/apic/Makefile b/arch/x86/kernel/apic/Makefile
> index a6fcaf16..75a2270 100644
> --- a/arch/x86/kernel/apic/Makefile
> +++ b/arch/x86/kernel/apic/Makefile
> @@ -12,6 +12,7 @@ obj-y				+= hw_nmi.o
>  
>  obj-$(CONFIG_X86_IO_APIC)	+= io_apic.o
>  obj-$(CONFIG_PCI_MSI)		+= msi.o
> +obj-$(CONFIG_MSI_IMS)		+= ims.o
>  obj-$(CONFIG_SMP)		+= ipi.o
>  
>  ifeq ($(CONFIG_X86_64),y)
> diff --git a/arch/x86/kernel/apic/ims.c b/arch/x86/kernel/apic/ims.c
> new file mode 100644
> index 0000000..d9808a5
> --- /dev/null
> +++ b/arch/x86/kernel/apic/ims.c
> @@ -0,0 +1,93 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * 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);
> +
> +	if (bus && dev->bus == bus) {
> +		fn = symbol_get(mdev_dev_to_parent_dev);
> +		ret = fn(dev);
> +		symbol_put(mdev_dev_to_parent_dev);
> +		symbol_put(mdev_bus_type);

Leaks a reference to the mdev module if dev->bus != bus.  The new
version of dev_is_mdev() unconditionally leaks a reference.  Thanks,

Alex

> +	}
> +
> +	return ret;
> +}
> +
> +static struct pci_dev *ims_get_pci_dev(struct device *dev)
> +{
> +	struct pci_dev *pdev;
> +
> +	if (dev_is_mdev(dev)) {
> +		struct device *parent = mdev_to_parent(dev);
> +
> +		pdev = to_pci_dev(parent);
> +	} else {
> +		pdev = to_pci_dev(dev);
> +	}
> +
> +	return pdev;
> +}
> +
> +int dev_ims_prepare(struct irq_domain *domain, struct device *dev, int nvec,
> +		    msi_alloc_info_t *arg)
> +{
> +	struct pci_dev *pdev = ims_get_pci_dev(dev);
> +
> +	init_irq_alloc_info(arg, NULL);
> +	arg->msi_dev = pdev;
> +	arg->type = X86_IRQ_ALLOC_TYPE_MSIX;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(dev_ims_prepare);
> +
> +#ifdef CONFIG_IRQ_REMAP
> +
> +static struct msi_domain_ops dev_ims_domain_ops = {
> +	.get_hwirq	= msi_get_hwirq,
> +	.msi_prepare	= dev_ims_prepare,
> +};
> +
> +static struct irq_chip dev_ims_ir_controller = {
> +	.name			= "IR-DEV-IMS",
> +	.irq_unmask		= dev_ims_unmask_irq,
> +	.irq_mask		= dev_ims_mask_irq,
> +	.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	= dev_ims_write_msg,
> +};
> +
> +static struct msi_domain_info ims_ir_domain_info = {
> +	.flags		= MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> +			  MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX,
> +	.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)
> +{
> +	return pci_msi_create_irq_domain(NULL, &ims_ir_domain_info, parent);
> +}
> +
> +#endif
> diff --git a/arch/x86/kernel/apic/msi.c b/arch/x86/kernel/apic/msi.c
> index 435bcda..65da813 100644
> --- a/arch/x86/kernel/apic/msi.c
> +++ b/arch/x86/kernel/apic/msi.c
> @@ -84,7 +84,7 @@ void native_teardown_msi_irq(unsigned int irq)
>  	irq_domain_free_irqs(irq, 1);
>  }
>  
> -static irq_hw_number_t pci_msi_get_hwirq(struct msi_domain_info *info,
> +irq_hw_number_t msi_get_hwirq(struct msi_domain_info *info,
>  					 msi_alloc_info_t *arg)
>  {
>  	return arg->msi_hwirq;
> @@ -116,7 +116,7 @@ void pci_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
>  EXPORT_SYMBOL_GPL(pci_msi_set_desc);
>  
>  static struct msi_domain_ops pci_msi_domain_ops = {
> -	.get_hwirq	= pci_msi_get_hwirq,
> +	.get_hwirq	= msi_get_hwirq,
>  	.msi_prepare	= pci_msi_prepare,
>  	.set_desc	= pci_msi_set_desc,
>  };
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index b558d4c..cecc6a6 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);
> +
>  void *mdev_get_drvdata(struct mdev_device *mdev)
>  {
>  	return mdev->driver_data;
> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
> index 7d92295..c21f130 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)
>  
>  struct mdev_type {
>  	struct kobject kobj;
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 0ce30ca..9dcbffe 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -144,5 +144,7 @@ void mdev_unregister_driver(struct mdev_driver *drv);
>  struct device *mdev_parent_dev(struct mdev_device *mdev);
>  struct device *mdev_dev(struct mdev_device *mdev);
>  struct mdev_device *mdev_from_dev(struct device *dev);
> +struct device *mdev_dev_to_parent_dev(struct device *dev);
>  
> +#define dev_is_mdev(d)          ((d)->bus == symbol_get(mdev_bus_type))
>  #endif /* MDEV_H */