The P2PDMA code currently provides two features under the same CONFIG_PCI_P2PDMA option:
1. Locate providers via pcim_p2pdma_provider() 2. Manage actual P2P DMA Other code (such as vfio-pci) depends on 1, without having a hard dependency on 2. A future commit expands the use of DMABUF in vfio-pci for non-P2P scenarios, relying on pcim_p2pdma_provider() always being present. If that depended on CONFIG_PCI_P2PDMA, it would make vfio-pci only available if CONFIG_ZONE_DEVICE is present (e.g. 64-bit systems), even when P2P is not needed. To resolve this, introduce CONFIG_PCI_P2PDMA_CORE which contains the basic provider functionality to make it available even if the CONFIG_PCI_P2PDMA feature is disabled or unavailable due to !CONFIG_ZONE_DEVICE. Users such as vfio-pci can enable their own P2P features based off the original CONFIG_PCI_P2PDMA (available when CONFIG_ZONE_DEVICE is set). Signed-off-by: Matt Evans <[email protected]> --- drivers/pci/Kconfig | 10 +++++----- drivers/pci/Makefile | 2 +- drivers/pci/p2pdma.c | 16 ++++++++++++++++ include/linux/pci-p2pdma.h | 24 ++++++++++++++---------- include/linux/pci.h | 2 +- 5 files changed, 37 insertions(+), 17 deletions(-) diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig index 33c88432b728..59d70bc84cc9 100644 --- a/drivers/pci/Kconfig +++ b/drivers/pci/Kconfig @@ -206,11 +206,7 @@ config PCIE_TPH config PCI_P2PDMA bool "PCI peer-to-peer transfer support" depends on ZONE_DEVICE - # - # The need for the scatterlist DMA bus address flag means PCI P2PDMA - # requires 64bit - # - depends on 64BIT + select PCI_P2PDMA_CORE select GENERIC_ALLOCATOR select NEED_SG_DMA_FLAGS help @@ -226,6 +222,10 @@ config PCI_P2PDMA If unsure, say N. +config PCI_P2PDMA_CORE + default n + bool + config PCI_LABEL def_bool y if (DMI || ACPI) select NLS diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile index 41ebc3b9a518..419b646a301d 100644 --- a/drivers/pci/Makefile +++ b/drivers/pci/Makefile @@ -30,7 +30,7 @@ obj-$(CONFIG_PCI_SYSCALL) += syscall.o obj-$(CONFIG_PCI_STUB) += pci-stub.o obj-$(CONFIG_PCI_PF_STUB) += pci-pf-stub.o obj-$(CONFIG_PCI_ECAM) += ecam.o -obj-$(CONFIG_PCI_P2PDMA) += p2pdma.o +obj-$(CONFIG_PCI_P2PDMA_CORE) += p2pdma.o obj-$(CONFIG_XEN_PCIDEV_FRONTEND) += xen-pcifront.o obj-$(CONFIG_VGA_ARB) += vgaarb.o obj-$(CONFIG_PCI_DOE) += doe.o diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 7c898542af8d..619d46c652b8 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -28,6 +28,14 @@ struct pci_p2pdma { struct p2pdma_provider mem[PCI_STD_NUM_BARS]; }; +/* + * CONFIG_PCI_P2PDMA_CORE provides just a bare-bones init and + * pcim_p2pdma_provider() interface (used by things like VFIO even if + * full P2PDMA isn't present). The full P2PDMA feature is under the + * CONFIG_PCI_P2PDMA option. + */ +#ifdef CONFIG_PCI_P2PDMA + struct pci_p2pdma_pagemap { struct dev_pagemap pgmap; struct p2pdma_provider *mem; @@ -226,6 +234,8 @@ static const struct dev_pagemap_ops p2pdma_pgmap_ops = { .folio_free = p2pdma_folio_free, }; +#endif /* CONFIG_PCI_P2PDMA */ + static void pci_p2pdma_release(void *data) { struct pci_dev *pdev = data; @@ -241,11 +251,13 @@ static void pci_p2pdma_release(void *data) synchronize_rcu(); xa_destroy(&p2pdma->map_types); +#ifdef CONFIG_PCI_P2PDMA if (!p2pdma->pool) return; gen_pool_destroy(p2pdma->pool); sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group); +#endif } /** @@ -330,6 +342,8 @@ struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar) } EXPORT_SYMBOL_GPL(pcim_p2pdma_provider); +#ifdef CONFIG_PCI_P2PDMA + static int pci_p2pdma_setup_pool(struct pci_dev *pdev) { struct pci_p2pdma *p2pdma; @@ -1207,3 +1221,5 @@ ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev, return sprintf(page, "%s\n", pci_name(p2p_dev)); } EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show); + +#endif diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h index 873de20a2247..4c42a7b2ee85 100644 --- a/include/linux/pci-p2pdma.h +++ b/include/linux/pci-p2pdma.h @@ -67,9 +67,22 @@ enum pci_p2pdma_map_type { PCI_P2PDMA_MAP_THRU_HOST_BRIDGE, }; -#ifdef CONFIG_PCI_P2PDMA +#ifdef CONFIG_PCI_P2PDMA_CORE int pcim_p2pdma_init(struct pci_dev *pdev); struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar); +#else +static inline int pcim_p2pdma_init(struct pci_dev *pdev) +{ + return -EOPNOTSUPP; +} +static inline struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, + int bar) +{ + return NULL; +} +#endif + +#ifdef CONFIG_PCI_P2PDMA int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, u64 offset); int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients, @@ -89,15 +102,6 @@ ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev, enum pci_p2pdma_map_type pci_p2pdma_map_type(struct p2pdma_provider *provider, struct device *dev); #else /* CONFIG_PCI_P2PDMA */ -static inline int pcim_p2pdma_init(struct pci_dev *pdev) -{ - return -EOPNOTSUPP; -} -static inline struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, - int bar) -{ - return NULL; -} static inline int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, u64 offset) { diff --git a/include/linux/pci.h b/include/linux/pci.h index 2c4454583c11..531aec355686 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -557,7 +557,7 @@ struct pci_dev { u16 pasid_cap; /* PASID Capability offset */ u16 pasid_features; #endif -#ifdef CONFIG_PCI_P2PDMA +#ifdef CONFIG_PCI_P2PDMA_CORE struct pci_p2pdma __rcu *p2pdma; #endif #ifdef CONFIG_PCI_DOE -- 2.47.3
