From: Leon Romanovsky leonro@nvidia.com
The PCIe ATS Enable bit covers the whole device, so P2PDMA cannot tell from it whether a client will translate a given address. Most devices translate any address once ATS is enabled, but some choose ATS per DMA mapping and can still use bus addresses for the rest.
Add pcim_p2pdma_set_ats_per_mapping() so the driver of such a device can declare that before P2PDMA starts treating clients with ATS enabled as translating everything. Keep it in the device's P2PDMA state, which already ends with the driver binding.
Reviewed-by: Thomas Hellström thomas.hellstrom@linux.intel.com Signed-off-by: Leon Romanovsky leonro@nvidia.com --- drivers/pci/p2pdma.c | 30 ++++++++++++++++++++++++++++++ include/linux/pci-p2pdma.h | 4 ++++ 2 files changed, 34 insertions(+)
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 6a05a5019daf..144314ab5fae 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -26,6 +26,7 @@ struct pci_p2pdma { struct gen_pool *pool; bool p2pmem_published; + bool ats_per_mapping; struct xarray map_types; struct p2pdma_provider mem[PCI_STD_NUM_BARS]; }; @@ -1750,6 +1751,35 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish) } EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
+/** + * pcim_p2pdma_set_ats_per_mapping - Declare per-mapping ATS for a client + * @pdev: PCI device that initiates peer-to-peer DMA + * + * Declare that @pdev issues Translated Requests only for the DMA mappings its + * driver sets up to use ATS, rather than for any address once ATS is enabled. + * P2PDMA then routes this client's Requests with the Address Type each query + * asks about, rather than the one its ATS Enable bit implies. + * + * Call it once pcim_p2pdma_init() has succeeded. Without P2PDMA state the + * declaration is dropped and the ATS Enable bit keeps deciding. + */ +void pcim_p2pdma_set_ats_per_mapping(struct pci_dev *pdev) +{ + struct pci_p2pdma *p2p; + + p2p = rcu_dereference_protected(pdev->p2pdma, 1); + if (!p2p) + /* + * ats_per_mapping is a performance optimization, + * if pcim_p2pdma_init() didn't set pdev->p2pdma pointer + * for some reason, let's simply use ATS global settings. + */ + return; + + p2p->ats_per_mapping = true; +} +EXPORT_SYMBOL_GPL(pcim_p2pdma_set_ats_per_mapping); + /** * pci_p2pdma_map_type_tlp - Determine the mapping type for P2PDMA transfers * @provider: P2PDMA provider structure diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h index dd17501ba1b6..ce389e18d023 100644 --- a/include/linux/pci-p2pdma.h +++ b/include/linux/pci-p2pdma.h @@ -82,6 +82,7 @@ struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev, unsigned int *nents, u32 length); void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl); void pci_p2pmem_publish(struct pci_dev *pdev, bool publish); +void pcim_p2pdma_set_ats_per_mapping(struct pci_dev *pdev); int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev, bool *use_p2pdma); ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev, @@ -138,6 +139,9 @@ static inline void pci_p2pmem_free_sgl(struct pci_dev *pdev, static inline void pci_p2pmem_publish(struct pci_dev *pdev, bool publish) { } +static inline void pcim_p2pdma_set_ats_per_mapping(struct pci_dev *pdev) +{ +} static inline int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev, bool *use_p2pdma) {