linux-kernel - Re: [PATCH] genirq/msi: Add the address and data that show MSI/MSIX

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Message-ID: <20250227163937.wv4hsucatyandde3@thinkpad>
Date: Thu, 27 Feb 2025 22:09:37 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Hans Zhang <18255117159@....com>
Cc: tglx@...utronix.de, kw@...ux.com, kwilczynski@...nel.org,
	bhelgaas@...gle.com, cassel@...nel.org, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] genirq/msi: Add the address and data that show MSI/MSIX

On Fri, Feb 28, 2025 at 12:28:21AM +0800, Hans Zhang wrote:
> Add to view the addresses and data stored in the MSI capability or the
> addresses and data stored in the MSIX vector table.
> 
> e.g.
> root@...t:/sys/bus/pci/devices/<dev>/msi_irqs# ls
> 86  87  88  89
> root@...t:/sys/bus/pci/devices/<dev>/msi_irqs# cat *
> msix
>  address_hi: 0x00000000
>  address_lo: 0x0e060040
>  msg_data: 0x00000000
> msix
>  address_hi: 0x00000000
>  address_lo: 0x0e060040
>  msg_data: 0x00000001
> msix
>  address_hi: 0x00000000
>  address_lo: 0x0e060040
>  msg_data: 0x00000002
> msix
>  address_hi: 0x00000000
>  address_lo: 0x0e060040
>  msg_data: 0x00000003
> 
> Signed-off-by: Hans Zhang <18255117159@....com>
> ---
>  kernel/irq/msi.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
> index 396a067a8a56..a37a3e535fb8 100644
> --- a/kernel/irq/msi.c
> +++ b/kernel/irq/msi.c
> @@ -503,8 +503,18 @@ static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr,
>  {
>  	/* MSI vs. MSIX is per device not per interrupt */
>  	bool is_msix = dev_is_pci(dev) ? to_pci_dev(dev)->msix_enabled : false;
> +	struct msi_desc *desc;
> +	u32 irq;
> +
> +	if (kstrtoint(attr->attr.name, 10, &irq) < 0)
> +		return 0;
>  
> -	return sysfs_emit(buf, "%s\n", is_msix ? "msix" : "msi");
> +	desc = irq_get_msi_desc(irq);
> +	return sysfs_emit(
> +		buf,
> +		"%s\n address_hi: 0x%08x\n address_lo: 0x%08x\n msg_data: 0x%08x\n",
> +		is_msix ? "msix" : "msi", desc->msg.address_hi,
> +		desc->msg.address_lo, desc->msg.data);

Sysfs is an ABI. You cannot change the semantics of an attribute.

- Mani

-- 
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