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PCI/P2PDMA: Introduce configfs/sysfs enable attribute helpers
Users of the P2PDMA infrastructure will typically need a way for the user to tell the kernel to use P2P resources. Typically this will be a simple on/off boolean operation but sometimes it may be desirable for the user to specify the exact device to use for the P2P operation. Add new helpers for attributes which take a boolean or a PCI device. Any boolean as accepted by strtobool() turn P2P on or off (such as 'y', 'n', '1', '0', etc). Specifying a full PCI device name/BDF will select the specific device. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
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@ -8,6 +8,8 @@
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* Copyright (c) 2018, Eideticom Inc.
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*/
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#define pr_fmt(fmt) "pci-p2pdma: " fmt
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#include <linux/ctype.h>
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#include <linux/pci-p2pdma.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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@ -721,3 +723,83 @@ int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
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return nents;
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}
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EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg);
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/**
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* pci_p2pdma_enable_store - parse a configfs/sysfs attribute store
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* to enable p2pdma
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* @page: contents of the value to be stored
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* @p2p_dev: returns the PCI device that was selected to be used
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* (if one was specified in the stored value)
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* @use_p2pdma: returns whether to enable p2pdma or not
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*
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* Parses an attribute value to decide whether to enable p2pdma.
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* The value can select a PCI device (using it's full BDF device
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* name) or a boolean (in any format strtobool() accepts). A false
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* value disables p2pdma, a true value expects the caller
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* to automatically find a compatible device and specifying a PCI device
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* expects the caller to use the specific provider.
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*
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* pci_p2pdma_enable_show() should be used as the show operation for
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* the attribute.
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*
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* Returns 0 on success
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*/
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int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
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bool *use_p2pdma)
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{
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struct device *dev;
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dev = bus_find_device_by_name(&pci_bus_type, NULL, page);
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if (dev) {
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*use_p2pdma = true;
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*p2p_dev = to_pci_dev(dev);
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if (!pci_has_p2pmem(*p2p_dev)) {
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pci_err(*p2p_dev,
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"PCI device has no peer-to-peer memory: %s\n",
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page);
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pci_dev_put(*p2p_dev);
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return -ENODEV;
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}
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return 0;
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} else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) {
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/*
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* If the user enters a PCI device that doesn't exist
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* like "0000:01:00.1", we don't want strtobool to think
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* it's a '0' when it's clearly not what the user wanted.
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* So we require 0's and 1's to be exactly one character.
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*/
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} else if (!strtobool(page, use_p2pdma)) {
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return 0;
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}
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pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page);
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return -ENODEV;
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}
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EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store);
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/**
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* pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating
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* whether p2pdma is enabled
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* @page: contents of the stored value
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* @p2p_dev: the selected p2p device (NULL if no device is selected)
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* @use_p2pdma: whether p2pdme has been enabled
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*
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* Attributes that use pci_p2pdma_enable_store() should use this function
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* to show the value of the attribute.
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*
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* Returns 0 on success
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*/
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ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
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bool use_p2pdma)
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{
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if (!use_p2pdma)
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return sprintf(page, "0\n");
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if (!p2p_dev)
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return sprintf(page, "1\n");
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return sprintf(page, "%s\n", pci_name(p2p_dev));
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}
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EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show);
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@ -32,6 +32,10 @@ void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl);
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void pci_p2pmem_publish(struct pci_dev *pdev, bool publish);
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int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
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enum dma_data_direction dir);
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int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
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bool *use_p2pdma);
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ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
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bool use_p2pdma);
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#else /* CONFIG_PCI_P2PDMA */
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static inline int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar,
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size_t size, u64 offset)
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@ -82,6 +86,17 @@ static inline int pci_p2pdma_map_sg(struct device *dev,
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{
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return 0;
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}
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static inline int pci_p2pdma_enable_store(const char *page,
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struct pci_dev **p2p_dev, bool *use_p2pdma)
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{
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*use_p2pdma = false;
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return 0;
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}
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static inline ssize_t pci_p2pdma_enable_show(char *page,
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struct pci_dev *p2p_dev, bool use_p2pdma)
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{
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return sprintf(page, "none\n");
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}
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#endif /* CONFIG_PCI_P2PDMA */
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