Re: [PATCH v9 (RESEND) 4/7] PCI: keystone: Add support for PVU-based DMA isolation on AM654

[Siddharth Vadapalli <s-vadapalli@ti.com>]

On Wed, Jul 16, 2025 at 01:39:47PM +0800, huaqian.li@siemens.com wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> The AM654 lacks an IOMMU, thus does not support isolating DMA requests
> from untrusted PCI devices to selected memory regions this way. Use
> static PVU-based protection instead. The PVU, when enabled, will only
> accept DMA requests that address previously configured regions.
> 
> Use the availability of a restricted-dma-pool memory region as trigger
> and register it as valid DMA target with the PVU. In addition, enable
> the mapping of requester IDs to VirtIDs in the PCI RC. Use only a single
> VirtID so far, catching all devices.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Li Hua Qian <huaqian.li@siemens.com>
> ---
>  drivers/pci/controller/dwc/pci-keystone.c | 106 ++++++++++++++++++++++
>  1 file changed, 106 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
> index 2b2632e513b5..fbf1bf43b7ca 100644
> --- a/drivers/pci/controller/dwc/pci-keystone.c
> +++ b/drivers/pci/controller/dwc/pci-keystone.c

[------------------email has been trimmed----------------------------]

> +static void ks_release_restricted_dma(struct platform_device *pdev)
> +{
> +	struct of_phandle_iterator it;
> +	struct resource phys;
> +	int err;
> +
> +	if (!IS_ENABLED(CONFIG_TI_PVU))
> +		return;
> +
> +	of_for_each_phandle(&it, err, pdev->dev.of_node, "memory-region",
> +			    NULL, 0) {
> +		if (of_device_is_compatible(it.node, "restricted-dma-pool") &&
> +		    of_address_to_resource(it.node, 0, &phys) == 0) {
> +			ti_pvu_remove_region(KS_PCI_VIRTID, &phys);
> +			break;
> +		}
> +	}
> +}
> +
>  static int ks_pcie_probe(struct platform_device *pdev)
>  {
>  	const struct dw_pcie_host_ops *host_ops;
> @@ -1284,6 +1384,10 @@ static int ks_pcie_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		goto err_get_sync;
>  
> +	ret = ks_init_restricted_dma(pdev);
> +	if (ret < 0)
> +		goto err_get_sync;
> +

Please move the above into the section specific to RC mode. This has
been agreed to by Jan at:
https://lore.kernel.org/r/e9716614-1849-4524-af4d-20587df365cf@siemens.com/

>  	switch (mode) {
>  	case DW_PCIE_RC_TYPE:
>  		if (!IS_ENABLED(CONFIG_PCI_KEYSTONE_HOST)) {
> @@ -1365,6 +1469,8 @@ static void ks_pcie_remove(struct platform_device *pdev)
>  	int num_lanes = ks_pcie->num_lanes;
>  	struct device *dev = &pdev->dev;
>  
> +	ks_release_restricted_dma(pdev);
> +

Regards,
Siddharth.