[PATCH v3 11/14] PCI/P2PDMA: Store mapping method in an xarray

Logan Gunthorpe
2019-08-12T17:31:03Z

When upstream_bridge_distance() is called, store the method required to map
the DMA transfers in an xarray so it can be looked up efficiently on the
hot path in pci_p2pdma_map_sg().

Link: https://lore.kernel.org/r/20190730163545.4915-12-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/p2pdma.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 771b45605853..db8224ff6e80 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -19,6 +19,7 @@
#include <linux/random.h>
#include <linux/seq_buf.h>
#include <linux/iommu.h>
+#include <linux/xarray.h>

enum pci_p2pdma_map_type {
PCI_P2PDMA_MAP_UNKNOWN = 0,
@@ -30,6 +31,7 @@ enum pci_p2pdma_map_type {
struct pci_p2pdma {
struct gen_pool *pool;
bool p2pmem_published;
+ struct xarray map_types;
};

struct pci_p2pdma_pagemap {
@@ -105,6 +107,7 @@ static void pci_p2pdma_release(void *data)

gen_pool_destroy(p2pdma->pool);
sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group);
+ xa_destroy(&p2pdma->map_types);
}

static int pci_p2pdma_setup(struct pci_dev *pdev)
@@ -116,6 +119,8 @@ static int pci_p2pdma_setup(struct pci_dev *pdev)
if (!p2p)
return -ENOMEM;

+ xa_init(&p2p->map_types);
+
p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev));
if (!p2p->pool)
goto out;
@@ -409,6 +414,12 @@ __upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
return PCI_P2PDMA_MAP_BUS_ADDR;
}

+static unsigned long map_types_idx(struct pci_dev *client)
+{
+ return (pci_domain_nr(client->bus) << 16) |
+ (client->bus->number << 8) | client->devfn;
+}
+
/*
* Find the distance through the nearest common upstream bridge between
* two PCI devices.
@@ -459,9 +470,13 @@ upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,

if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) {
if (!host_bridge_whitelist(provider, client))
- return PCI_P2PDMA_MAP_NOT_SUPPORTED;
+ map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
}

+ if (provider->p2pdma)
+ xa_store(&provider->p2pdma->map_types, map_types_idx(client),
+ xa_mk_value(map_type), GFP_KERNEL);
+
return map_type;
}

--
2.20.1