linux-kernel - Re: [PATCH v3 7/7] PCI: hv: Get vPCI MSI IRQ domain from DT

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Message-ID: <Zq2F-l2FWIrQ2Jt1@liuwe-devbox-debian-v2>
Date: Sat, 3 Aug 2024 01:20:58 +0000
From: Wei Liu <wei.liu@...nel.org>
To: Roman Kisel <romank@...ux.microsoft.com>
Cc: arnd@...db.de, bhelgaas@...gle.com, bp@...en8.de,
	catalin.marinas@....com, dave.hansen@...ux.intel.com,
	decui@...rosoft.com, haiyangz@...rosoft.com, hpa@...or.com,
	kw@...ux.com, kys@...rosoft.com, lenb@...nel.org,
	lpieralisi@...nel.org, mingo@...hat.com, rafael@...nel.org,
	robh@...nel.org, tglx@...utronix.de, wei.liu@...nel.org,
	will@...nel.org, linux-acpi@...r.kernel.org,
	linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, x86@...nel.org, apais@...rosoft.com,
	benhill@...rosoft.com, ssengar@...rosoft.com,
	sunilmut@...rosoft.com, vdso@...bites.dev
Subject: Re: [PATCH v3 7/7] PCI: hv: Get vPCI MSI IRQ domain from DT

On Fri, Jul 26, 2024 at 03:59:10PM -0700, Roman Kisel wrote:
> The hyperv-pci driver uses ACPI for MSI IRQ domain configuration on
> arm64. It won't be able to do that in the VTL mode where only DeviceTree
> can be used.
> 
> Update the hyperv-pci driver to get vPCI MSI IRQ domain in the DeviceTree
> case, too.
> 
> Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>
> ---
>  drivers/hv/vmbus_drv.c              | 23 +++++++-----
>  drivers/pci/controller/pci-hyperv.c | 55 +++++++++++++++++++++++++++--
>  include/linux/hyperv.h              |  2 ++
>  3 files changed, 69 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 7eee7caff5f6..038bd9be64b7 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -45,7 +45,8 @@ struct vmbus_dynid {
>  	struct hv_vmbus_device_id id;
>  };
>  
> -static struct device  *hv_dev;
> +/* VMBus Root Device */
> +static struct device  *vmbus_root_device;

You're changing the name of the variable. That should preferably be done
in a separate patch. That's going to make this patch shorter and easier
to review.

>  
>  static int hyperv_cpuhp_online;
>  
> @@ -80,9 +81,15 @@ static struct resource *fb_mmio;
>  static struct resource *hyperv_mmio;
>  static DEFINE_MUTEX(hyperv_mmio_lock);
>  
> +struct device *get_vmbus_root_device(void)
> +{
> +	return vmbus_root_device;
> +}
> +EXPORT_SYMBOL_GPL(get_vmbus_root_device);

I would like you to add "hv_" prefix to this exported symbol, or rename
it to "vmbus_get_root_device()".

> +
>  static int vmbus_exists(void)
>  {
> -	if (hv_dev == NULL)
> +	if (vmbus_root_device == NULL)
>  		return -ENODEV;
>  
>  	return 0;
> @@ -861,7 +868,7 @@ static int vmbus_dma_configure(struct device *child_device)
>  	 * On x86/x64 coherence is assumed and these calls have no effect.
>  	 */
>  	hv_setup_dma_ops(child_device,
> -		device_get_dma_attr(hv_dev) == DEV_DMA_COHERENT);
> +		device_get_dma_attr(vmbus_root_device) == DEV_DMA_COHERENT);
>  	return 0;
>  }
>  
> @@ -1892,7 +1899,7 @@ int vmbus_device_register(struct hv_device *child_device_obj)
>  		     &child_device_obj->channel->offermsg.offer.if_instance);
>  
>  	child_device_obj->device.bus = &hv_bus;
> -	child_device_obj->device.parent = hv_dev;
> +	child_device_obj->device.parent = vmbus_root_device;
>  	child_device_obj->device.release = vmbus_device_release;
>  
>  	child_device_obj->device.dma_parms = &child_device_obj->dma_parms;
> @@ -2253,7 +2260,7 @@ static int vmbus_acpi_add(struct platform_device *pdev)
>  	struct acpi_device *ancestor;
>  	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
>  
> -	hv_dev = &device->dev;
> +	vmbus_root_device = &device->dev;
>  
>  	/*
>  	 * Older versions of Hyper-V for ARM64 fail to include the _CCA
> @@ -2342,7 +2349,7 @@ static int vmbus_device_add(struct platform_device *pdev)
>  	struct device_node *np = pdev->dev.of_node;
>  	int ret;
>  
> -	hv_dev = &pdev->dev;
> +	vmbus_root_device = &pdev->dev;
>  
>  	ret = of_range_parser_init(&parser, np);
>  	if (ret)
> @@ -2675,7 +2682,7 @@ static int __init hv_acpi_init(void)
>  	if (ret)
>  		return ret;
>  
> -	if (!hv_dev) {
> +	if (!vmbus_root_device) {
>  		ret = -ENODEV;
>  		goto cleanup;
>  	}
> @@ -2706,7 +2713,7 @@ static int __init hv_acpi_init(void)
>  
>  cleanup:
>  	platform_driver_unregister(&vmbus_platform_driver);
> -	hv_dev = NULL;
> +	vmbus_root_device = NULL;
>  	return ret;
>  }
>  
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 5992280e8110..cdecefd1f9bd 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -50,6 +50,7 @@
>  #include <linux/irqdomain.h>
>  #include <linux/acpi.h>
>  #include <linux/sizes.h>
> +#include <linux/of_irq.h>
>  #include <asm/mshyperv.h>
>  
>  /*
> @@ -887,6 +888,35 @@ static const struct irq_domain_ops hv_pci_domain_ops = {
>  	.activate = hv_pci_vec_irq_domain_activate,
>  };
>  
> +#ifdef CONFIG_OF
> +
> +static struct irq_domain *hv_pci_of_irq_domain_parent(void)
> +{
> +	struct device_node *parent;
> +	struct irq_domain *domain;
> +
> +	parent = of_irq_find_parent(to_platform_device(get_vmbus_root_device())->dev.of_node);
> +	domain = NULL;
> +	if (parent) {
> +		domain = irq_find_host(parent);
> +		of_node_put(parent);
> +	}
> +

I cannot really comment on the ARM side of things around how this system
is set up. I will leave that to someone who's more familiar with the
matter to review.

Thanks,
Wei.