Re: [PATCH v6 4/7] PCI: keystone: Add support for PVU-based DMA isolation on AM654

[Vignesh Raghavendra <vigneshr@ti.com>]

On 09/09/24 22:33, Jan Kiszka 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. This may be extended later on.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> CC: Lorenzo Pieralisi <lpieralisi@kernel.org>
> CC: "Krzysztof Wilczyński" <kw@linux.com>
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: linux-pci@vger.kernel.org
> ---
>  drivers/pci/controller/dwc/pci-keystone.c | 108 ++++++++++++++++++++++
>  1 file changed, 108 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
> index 2219b1a866fa..a5954cae6d5d 100644
> --- a/drivers/pci/controller/dwc/pci-keystone.c
> +++ b/drivers/pci/controller/dwc/pci-keystone.c
> @@ -19,6 +19,7 @@
>  #include <linux/mfd/syscon.h>
>  #include <linux/msi.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
>  #include <linux/of_irq.h>
>  #include <linux/of_pci.h>
>  #include <linux/phy/phy.h>
> @@ -26,6 +27,7 @@
>  #include <linux/regmap.h>
>  #include <linux/resource.h>
>  #include <linux/signal.h>
> +#include <linux/ti-pvu.h>
>  
>  #include "../../pci.h"
>  #include "pcie-designware.h"
> @@ -111,6 +113,16 @@
>  
>  #define PCI_DEVICE_ID_TI_AM654X		0xb00c
>  
> +#define KS_PCI_VIRTID			0
> +
> +#define PCIE_VMAP_xP_CTRL		0x0
> +#define PCIE_VMAP_xP_REQID		0x4
> +#define PCIE_VMAP_xP_VIRTID		0x8
> +
> +#define PCIE_VMAP_xP_CTRL_EN		BIT(0)
> +
> +#define PCIE_VMAP_xP_VIRTID_VID_MASK	0xfff
> +
>  struct ks_pcie_of_data {
>  	enum dw_pcie_device_mode mode;
>  	const struct dw_pcie_host_ops *host_ops;
> @@ -1125,6 +1137,96 @@ static const struct of_device_id ks_pcie_of_match[] = {
>  	{ },
>  };
>  
> +#ifdef CONFIG_TI_PVU
> +static int ks_init_vmap(struct platform_device *pdev, const char *vmap_name)
> +{
> +	struct resource *res;
> +	void __iomem *base;
> +	u32 val;
> +

Nit:

	if (!IS_ENABLED(CONFIG_TI_PVU))
		return 0;


this looks cleaner than #ifdef.. #else..#endif .


Rest LGTM

> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, vmap_name);
> +	base = devm_pci_remap_cfg_resource(&pdev->dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	writel(0, base + PCIE_VMAP_xP_REQID);
> +
> +	val = readl(base + PCIE_VMAP_xP_VIRTID);
> +	val &= ~PCIE_VMAP_xP_VIRTID_VID_MASK;
> +	val |= KS_PCI_VIRTID;
> +	writel(val, base + PCIE_VMAP_xP_VIRTID);
> +
> +	val = readl(base + PCIE_VMAP_xP_CTRL);
> +	val |= PCIE_VMAP_xP_CTRL_EN;
> +	writel(val, base + PCIE_VMAP_xP_CTRL);
> +
> +	return 0;
> +}
> +
> +static int ks_init_restricted_dma(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct of_phandle_iterator it;
> +	struct resource phys;
> +	int err;
> +
> +	/* Only process the first restricted dma pool, more are not allowed */
> +	of_for_each_phandle(&it, err, dev->of_node, "memory-region",
> +			    NULL, 0) {
> +		if (of_device_is_compatible(it.node, "restricted-dma-pool"))
> +			break;
> +	}
> +	if (err)
> +		return err == -ENOENT ? 0 : err;
> +
> +	err = of_address_to_resource(it.node, 0, &phys);
> +	if (err < 0) {
> +		dev_err(dev, "failed to parse memory region %pOF: %d\n",
> +			it.node, err);
> +		return 0;
> +	}
> +
> +	/* Map all incoming requests on low and high prio port to virtID 0 */
> +	err = ks_init_vmap(pdev, "vmap_lp");
> +	if (err)
> +		return err;
> +	err = ks_init_vmap(pdev, "vmap_hp");
> +	if (err)
> +		return err;
> +
> +	/*
> +	 * Enforce DMA pool usage with the help of the PVU.
> +	 * Any request outside will be dropped and raise an error at the PVU.
> +	 */
> +	return ti_pvu_create_region(KS_PCI_VIRTID, &phys);
> +}
> +
> +static void ks_release_restricted_dma(struct platform_device *pdev)
> +{
> +	struct of_phandle_iterator it;
> +	struct resource phys;
> +	int err;
> +
> +	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;
> +		}
> +	}
> +}
> +#else
> +static inline int ks_init_restricted_dma(struct platform_device *pdev)
> +{
> +	return 0;
> +}
> +
> +static inline void ks_release_restricted_dma(struct platform_device *pdev)
> +{
> +}
> +#endif
> +
>  static int ks_pcie_probe(struct platform_device *pdev)
>  {
>  	const struct dw_pcie_host_ops *host_ops;
> @@ -1273,6 +1375,10 @@ 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;
> +
>  	switch (mode) {
>  	case DW_PCIE_RC_TYPE:
>  		if (!IS_ENABLED(CONFIG_PCI_KEYSTONE_HOST)) {
> @@ -1354,6 +1460,8 @@ 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);
> +
>  	pm_runtime_put(dev);
>  	pm_runtime_disable(dev);
>  	ks_pcie_disable_phy(ks_pcie);

-- 
Regards
Vignesh