linux-kernel - Re: [PATCH v4] PCI: vmd: Add the module param to adjust MSI mode

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Date:   Mon, 27 Mar 2023 14:39:04 +0800
From:   Xinghui Li <korantwork@...il.com>
To:     helgaas@...nel.org, nirmal.patel@...ux.intel.com,
        kbusch@...nel.org, jonathan.derrick@...ux.dev,
        lpieralisi@...nel.org
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xinghui Li <korantli@...cent.com>
Subject: Re: [PATCH v4] PCI: vmd: Add the module param to adjust MSI mode

Friendly ping~


On Mon, Mar 20, 2023 at 9:23 PM <korantwork@...il.com> wrote:
>
> From: Xinghui Li <korantli@...cent.com>
>
> In the legacy, the vmd MSI mode can only be adjusted by configuring
> vmd_ids table. This patch adds another way to adjust MSI mode by
> adjusting module param, which allows users easier to adjust the vmd
> according to the I/O scenario without rebuilding driver. There are two
> params that could be recognized: on, off. The default param is NULL,
> the goal is not to effect the existing settings of the device.
>
> Signed-off-by: Xinghui Li <korantli@...cent.com>
> Reviewed-by: Nirmal Patel <nirmal.patel@...ux.intel.com>
> ---
>  drivers/pci/controller/vmd.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index 990630ec57c6..fb61181baa9e 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -34,6 +34,19 @@
>  #define MB2_SHADOW_OFFSET      0x2000
>  #define MB2_SHADOW_SIZE                16
>
> +/*
> + * The VMD msi_remap module parameter provides the alternative way
> + * to adjust MSI mode when loading vmd.ko other than vmd_ids table.
> + * There are two params could be recognized:
> + *
> + * off: disable MSI remapping
> + * on:  enable MSI remapping
> + *
> + */
> +static char *msi_remap;
> +module_param(msi_remap, charp, 0444);
> +MODULE_PARM_DESC(msi_remap, "Whether to enable MSI remapping function");
> +
>  enum vmd_features {
>         /*
>          * Device may contain registers which hint the physical location of the
> @@ -875,6 +888,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>                         return ret;
>
>                 vmd_set_msi_remapping(vmd, true);
> +               dev_info(&vmd->dev->dev, "init vmd with remapping MSI\n");
>
>                 ret = vmd_create_irq_domain(vmd);
>                 if (ret)
> @@ -887,6 +901,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>                 irq_domain_update_bus_token(vmd->irq_domain, DOMAIN_BUS_VMD_MSI);
>         } else {
>                 vmd_set_msi_remapping(vmd, false);
> +               dev_info(&vmd->dev->dev, "init vmd with bypass MSI\n");
>         }
>
>         pci_add_resource(&resources, &vmd->resources[0]);
> @@ -955,6 +970,16 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>         return 0;
>  }
>
> +static void vmd_config_msi_remap_param(unsigned long *features)
> +{
> +       if (msi_remap) {
> +               if (strcmp(msi_remap, "on") == 0)
> +                       *features &= ~(VMD_FEAT_CAN_BYPASS_MSI_REMAP);
> +               else if (strcmp(msi_remap, "off") == 0)
> +                       *features |= VMD_FEAT_CAN_BYPASS_MSI_REMAP;
> +       }
> +}
> +
>  static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  {
>         unsigned long features = (unsigned long) id->driver_data;
> @@ -984,6 +1009,8 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
>         if (err < 0)
>                 goto out_release_instance;
>
> +       vmd_config_msi_remap_param(&features);
> +
>         vmd->cfgbar = pcim_iomap(dev, VMD_CFGBAR, 0);
>         if (!vmd->cfgbar) {
>                 err = -ENOMEM;
> --
> 2.31.1
>