linux-kernel - Re: [PATCH v3 09/11] PCI: endpoint: pci-epf-test: Add smoke test for EPC remote resource API

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Message-ID: <aYOf5DXQjVEpcwCE@lizhi-Precision-Tower-5810>
Date: Wed, 4 Feb 2026 14:37:08 -0500
From: Frank Li <Frank.li@....com>
To: Koichiro Den <den@...inux.co.jp>
Cc: vkoul@...nel.org, mani@...nel.org, jingoohan1@...il.com,
	lpieralisi@...nel.org, kwilczynski@...nel.org, robh@...nel.org,
	bhelgaas@...gle.com, dmaengine@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/11] PCI: endpoint: pci-epf-test: Add smoke test for
 EPC remote resource API

On Wed, Feb 04, 2026 at 11:54:37PM +0900, Koichiro Den wrote:
> Add a new pci-epf-test command that exercises the newly added EPC API
> pci_epc_get_remote_resources().
>
> The test is intentionally a smoke test. It verifies that the API either
> returns -EOPNOTSUPP or a well-formed resource list (non-zero phys/size
> and known resource types). The result is reported to the host via a
> status bit and an interrupt, consistent with existing pci-epf-test
> commands.
>
> Signed-off-by: Koichiro Den <den@...inux.co.jp>
> ---
>  drivers/pci/endpoint/functions/pci-epf-test.c | 88 +++++++++++++++++++
>  1 file changed, 88 insertions(+)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 6952ee418622..6446a0a23865 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -35,6 +35,7 @@
>  #define COMMAND_DISABLE_DOORBELL	BIT(7)
>  #define COMMAND_BAR_SUBRANGE_SETUP	BIT(8)
>  #define COMMAND_BAR_SUBRANGE_CLEAR	BIT(9)
> +#define COMMAND_EPC_API			BIT(10)
>
>  #define STATUS_READ_SUCCESS		BIT(0)
>  #define STATUS_READ_FAIL		BIT(1)
> @@ -54,6 +55,8 @@
>  #define STATUS_BAR_SUBRANGE_SETUP_FAIL		BIT(15)
>  #define STATUS_BAR_SUBRANGE_CLEAR_SUCCESS	BIT(16)
>  #define STATUS_BAR_SUBRANGE_CLEAR_FAIL		BIT(17)
> +#define STATUS_EPC_API_SUCCESS		BIT(18)
> +#define STATUS_EPC_API_FAIL		BIT(19)
>
>  #define FLAG_USE_DMA			BIT(0)
>
> @@ -967,6 +970,87 @@ static void pci_epf_test_bar_subrange_clear(struct pci_epf_test *epf_test,
>  	reg->status = cpu_to_le32(status);
>  }
>
> +static void pci_epf_test_epc_api(struct pci_epf_test *epf_test,
> +				 struct pci_epf_test_reg *reg)
> +{
> +	struct pci_epc_remote_resource *resources = NULL;
> +	u32 status = le32_to_cpu(reg->status);
> +	struct pci_epf *epf = epf_test->epf;
> +	struct device *dev = &epf->dev;
> +	struct pci_epc *epc = epf->epc;
> +	int num_resources;
> +	int ret, i;
> +
> +	num_resources = pci_epc_get_remote_resources(epc, epf->func_no,
> +						     epf->vfunc_no, NULL, 0);
> +	if (num_resources == -EOPNOTSUPP || num_resources == 0)
> +		goto out_success;
> +	if (num_resources < 0)
> +		goto err;
> +
> +	resources = kcalloc(num_resources, sizeof(*resources), GFP_KERNEL);

use auto cleanup
	struct pci_epc_remote_resource *resources __free(kfree) =
		kcalloc(num_resources, sizeof(*resources), GFP_KERNEL);

> +	if (!resources)
> +		goto err;
> +
> +	ret = pci_epc_get_remote_resources(epc, epf->func_no, epf->vfunc_no,
> +					   resources, num_resources);
> +	if (ret < 0) {
> +		dev_err(dev, "EPC remote resource query failed: %d\n", ret);
> +		goto err_free;
> +	}
> +	if (ret > num_resources) {
> +		dev_err(dev, "EPC API returned %d resources (max %d)\n",
> +			ret, num_resources);
> +		goto err_free;
> +	}
> +
> +	for (i = 0; i < ret; i++) {
> +		struct pci_epc_remote_resource *res = &resources[i];
> +
> +		if (!res->phys_addr || !res->size) {
> +			dev_err(dev,
> +				"Invalid remote resource[%d] (type=%d phys=%pa size=%llu)\n",
> +				i, res->type, &res->phys_addr, res->size);
> +			goto err_free;
> +		}
> +
> +		/* Guard against address overflow */
> +		if (res->phys_addr + res->size < res->phys_addr) {
> +			dev_err(dev,
> +				"Remote resource[%d] overflow (phys=%pa size=%llu)\n",
> +				i, &res->phys_addr, res->size);
> +			goto err_free;
> +		}
> +
> +		switch (res->type) {
> +		case PCI_EPC_RR_DMA_CTRL_MMIO:
> +			/* Generic checks above are sufficient. */
> +			break;
> +		case PCI_EPC_RR_DMA_CHAN_DESC:
> +			/*
> +			 * hw_chan_id and ep2rc are informational. No extra validation
> +			 * beyond the generic checks above is needed.
> +			 */
> +			break;
> +		default:
> +			dev_err(dev, "Unknown remote resource type %d\n", res->type);
> +			goto err_free;

can you call subrange to map to one of bar?

Frank
> +		}
> +	}
> +
> +out_success:
> +	kfree(resources);
> +	status |= STATUS_EPC_API_SUCCESS;
> +	reg->status = cpu_to_le32(status);
> +	return;
> +
> +err_free:
> +	kfree(resources);
> +err:
> +	status |= STATUS_EPC_API_FAIL;
> +	reg->status = cpu_to_le32(status);
> +}
> +
>  static void pci_epf_test_cmd_handler(struct work_struct *work)
>  {
>  	u32 command;
> @@ -1030,6 +1114,10 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
>  		pci_epf_test_bar_subrange_clear(epf_test, reg);
>  		pci_epf_test_raise_irq(epf_test, reg);
>  		break;
> +	case COMMAND_EPC_API:
> +		pci_epf_test_epc_api(epf_test, reg);
> +		pci_epf_test_raise_irq(epf_test, reg);
> +		break;
>  	default:
>  		dev_err(dev, "Invalid command 0x%x\n", command);
>  		break;
> --
> 2.51.0
>