Update the p2p_dma_distance() to determine inter-switch P2P links existing
between two switches and use this to calculate the DMA distance between
two devices.
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@xxxxxxxxxxxx>
---
drivers/pci/p2pdma.c | 17 ++++++++++++++++-
drivers/pci/pcie/portdrv.c | 34 ++++++++++++++++++++++++++++++++++
drivers/pci/pcie/portdrv.h | 2 ++
3 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 4f47a13cb500..eed3b69e7293 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -21,6 +21,8 @@
#include <linux/seq_buf.h>
#include <linux/xarray.h>
+extern bool pcie_port_is_p2p_link_available(struct pci_dev *a, struct pci_dev *b);
+
struct pci_p2pdma {
struct gen_pool *pool;
bool p2pmem_published;
@@ -576,7 +578,7 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
int *dist, bool verbose)
{
enum pci_p2pdma_map_type map_type = PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
- struct pci_dev *a = provider, *b = client, *bb;
+ struct pci_dev *a = provider, *b = client, *bb, *b_p2p_link = NULL;
bool acs_redirects = false;
struct pci_p2pdma *p2pdma;
struct seq_buf acs_list;
@@ -606,6 +608,16 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
if (a == bb)
goto check_b_path_acs;
+ /*
+ * If both upstream bridges have Inter switch P2P link
+ * available, P2P DMA distance can account for optimized
+ * path.
+ */
+ if (pcie_port_is_p2p_link_available(a, bb)) {
+ b_p2p_link = bb;
+ goto check_b_path_acs;
+ }
+
bb = pci_upstream_bridge(bb);
dist_b++;
}
@@ -629,6 +641,9 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
acs_cnt++;
}
+ if (bb == b_p2p_link)
+ break;
+
bb = pci_upstream_bridge(bb);
}
diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index c940b4b242fd..2fe1598fc684 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -104,6 +104,40 @@ static bool pcie_port_is_p2p_supported(struct pci_dev *dev)
return false;
}
+/**
+ * pcie_port_is_p2p_link_available: Determine if a P2P link is available
+ * between the two upstream bridges. The serial number of the two devices
+ * will be compared and if they are same then it is considered that the P2P
+ * link is available.
+ *
+ * Return value: true if inter switch P2P is available, return false otherwise.
+ */
+bool pcie_port_is_p2p_link_available(struct pci_dev *a, struct pci_dev *b)
+{
+ u64 dsn_a, dsn_b;
+
+ /*
+ * Check if the devices support Inter switch P2P.
+ */
+ if (!pcie_port_is_p2p_supported(a) ||
+ !pcie_port_is_p2p_supported(b))
+ return false;
+
+ dsn_a = pci_get_dsn(a);
+ if (!dsn_a)
+ return false;
+
+ dsn_b = pci_get_dsn(b);
+ if (!dsn_b)
+ return false;
+
+ if (dsn_a == dsn_b)
+ return true;
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(pcie_port_is_p2p_link_available);
+
/*
* Traverse list of all PCI bridges and find devices that support Inter switch P2P
* and have the same serial number to create report the BDF over sysfs.
diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index 1be06cb45665..b341aad6eb49 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -130,5 +130,7 @@ static inline bool pcie_pme_no_msi(void) { return false; }
static inline void pcie_pme_interrupt_enable(struct pci_dev *dev, bool en) {}
#endif /* !CONFIG_PCIE_PME */
+bool pcie_port_is_p2p_link_available(struct pci_dev *a, struct pci_dev *b);
+
struct device *pcie_port_find_device(struct pci_dev *dev, u32 service);
#endif /* _PORTDRV_H_ */
--
2.43.0
