Re: [PATCH v2] PCI: vmd: Clear PCI_INTERRUPT_LINE for VMD sub-devices

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Tue, Aug 20, 2024 at 03:32:13PM -0700, Nirmal Patel wrote:
> VMD does not support INTx for devices downstream from a VMD endpoint.
> So initialize the PCI_INTERRUPT_LINE to 0 for all NVMe devices under
> VMD to ensure other applications don't try to set up an INTx for them.
> 
> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>

I shared a diff to put it in pci_assign_irq() and you said that you were going
to test it [1]. I don't see a reply to that and now you came up with another
approach.

What happened inbetween?

- Mani

[1] https://lore.kernel.org/linux-pci/20240801115756.0000272e@linux.intel.com

> ---
> v2->v1: Change the execution from fixup.c to vmd.c
> ---
>  drivers/pci/controller/vmd.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index a726de0af011..2e9b99969b81 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -778,6 +778,18 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
>  	return 0;
>  }
>  
> +/*
> + * Some applications like SPDK reads PCI_INTERRUPT_LINE to decide
> + * whether INTx is enabled or not. Since VMD doesn't support INTx,
> + * write 0 to all NVMe devices under VMD.
> + */
> +static int vmd_clr_int_line_reg(struct pci_dev *dev, void *userdata)
> +{
> +	if(dev->class == PCI_CLASS_STORAGE_EXPRESS)
> +		pci_write_config_byte(dev, PCI_INTERRUPT_LINE, 0);
> +	return 0;
> +}
> +
>  static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  {
>  	struct pci_sysdata *sd = &vmd->sysdata;
> @@ -932,6 +944,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  
>  	pci_scan_child_bus(vmd->bus);
>  	vmd_domain_reset(vmd);
> +	pci_walk_bus(vmd->bus, vmd_clr_int_line_reg, &features);
>  
>  	/* When Intel VMD is enabled, the OS does not discover the Root Ports
>  	 * owned by Intel VMD within the MMCFG space. pci_reset_bus() applies
> -- 
> 2.39.1
> 
> 

-- 
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