[PATCH v2 11/14] PCI/P2PDMA: Store mapping method in an xarray

Logan Gunthorpe
2019-07-30T16:36:36Z

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

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
drivers/pci/p2pdma.c | 40 +++++++++++++++++++++++++++++++++++-----
1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index fe647bd8f947..010aa8742bec 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -19,10 +19,19 @@
#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,
+ PCI_P2PDMA_MAP_NOT_SUPPORTED,
+ PCI_P2PDMA_MAP_BUS_ADDR,
+ PCI_P2PDMA_MAP_THRU_IOMMU,
+};

struct pci_p2pdma {
struct gen_pool *pool;
bool p2pmem_published;
+ struct xarray map_types;
};

struct pci_p2pdma_pagemap {
@@ -98,6 +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)
@@ -109,6 +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;
@@ -404,6 +416,12 @@ static int __upstream_bridge_distance(struct pci_dev *provider,
return dist_a + dist_b;
}

+static int 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.
@@ -446,17 +464,29 @@ static int upstream_bridge_distance(struct pci_dev *provider,
struct pci_dev *client,
struct seq_buf *acs_list)
{
+ enum pci_p2pdma_map_type map_type;
int dist;

dist = __upstream_bridge_distance(provider, client, acs_list);

- if (!(dist & P2PDMA_THRU_HOST_BRIDGE))
- return dist;
+ if (!(dist & P2PDMA_THRU_HOST_BRIDGE)) {
+ map_type = PCI_P2PDMA_MAP_BUS_ADDR;
+ goto store_map_type_and_return;
+ }
+
+ if (host_bridge_whitelist(provider, client)) {
+ map_type = PCI_P2PDMA_MAP_THRU_IOMMU;
+ } else {
+ dist |= P2PDMA_NOT_SUPPORTED;
+ map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
+ }

- if (host_bridge_whitelist(provider, client))
- return dist;
+store_map_type_and_return:
+ if (provider->p2pdma)
+ xa_store(&provider->p2pdma->map_types, map_types_idx(client),
+ xa_mk_value(map_type), GFP_KERNEL);

- return dist | P2PDMA_NOT_SUPPORTED;
+ return dist;
}

static int upstream_bridge_distance_warn(struct pci_dev *provider,
--
2.20.1