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Subject[PATCH 5/5] PCI/ATS: Cache PASID Capability offset
Date
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

Previously each PASID interface searched for the PASID Capability. Cache
the capability offset the first time we use it instead of searching each
time.

[bhelgaas: commit log, reorder patch to later, save offset directly in
pci_enable_pasid() rather than adding pci_pasid_init()]
Link: https://lore.kernel.org/r/4957778959fa34eab3e8b3065d1951989c61cb0f.1567029860.git.sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/ats.c | 43 +++++++++++++++++++++----------------------
include/linux/pci.h | 1 +
2 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index bc463e2ecc61..cb4f62da7b8a 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -305,7 +305,7 @@ EXPORT_SYMBOL_GPL(pci_reset_pri);
int pci_enable_pasid(struct pci_dev *pdev, int features)
{
u16 control, supported;
- int pos;
+ int pasid = pdev->pasid_cap;

/*
* VFs must not implement the PASID Capability, but if a PF
@@ -323,11 +323,14 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
if (!pdev->eetlp_prefix_path)
return -EINVAL;

- pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
- if (!pos)
- return -EINVAL;
+ if (!pasid) {
+ pasid = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
+ if (!pasid)
+ return -EINVAL;
+ pdev->pasid_cap = pasid;
+ }

- pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+ pci_read_config_word(pdev, pasid + PCI_PASID_CAP, &supported);
supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;

/* User wants to enable anything unsupported? */
@@ -337,7 +340,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
control = PCI_PASID_CTRL_ENABLE | features;
pdev->pasid_features = features;

- pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+ pci_write_config_word(pdev, pasid + PCI_PASID_CTRL, control);

pdev->pasid_enabled = 1;

@@ -352,7 +355,7 @@ EXPORT_SYMBOL_GPL(pci_enable_pasid);
void pci_disable_pasid(struct pci_dev *pdev)
{
u16 control = 0;
- int pos;
+ int pasid = pdev->pasid_cap;

/* VFs share the PF PASID configuration */
if (pdev->is_virtfn)
@@ -361,11 +364,10 @@ void pci_disable_pasid(struct pci_dev *pdev)
if (WARN_ON(!pdev->pasid_enabled))
return;

- pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
- if (!pos)
+ if (!pasid)
return;

- pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+ pci_write_config_word(pdev, pasid + PCI_PASID_CTRL, control);

pdev->pasid_enabled = 0;
}
@@ -378,7 +380,7 @@ EXPORT_SYMBOL_GPL(pci_disable_pasid);
void pci_restore_pasid_state(struct pci_dev *pdev)
{
u16 control;
- int pos;
+ int pasid = pdev->pasid_cap;

if (pdev->is_virtfn)
return;
@@ -386,12 +388,11 @@ void pci_restore_pasid_state(struct pci_dev *pdev)
if (!pdev->pasid_enabled)
return;

- pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
- if (!pos)
+ if (!pasid)
return;

control = PCI_PASID_CTRL_ENABLE | pdev->pasid_features;
- pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+ pci_write_config_word(pdev, pasid + PCI_PASID_CTRL, control);
}
EXPORT_SYMBOL_GPL(pci_restore_pasid_state);

@@ -408,16 +409,15 @@ EXPORT_SYMBOL_GPL(pci_restore_pasid_state);
int pci_pasid_features(struct pci_dev *pdev)
{
u16 supported;
- int pos;
+ int pasid = pdev->pasid_cap;

if (pdev->is_virtfn)
pdev = pci_physfn(pdev);

- pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
- if (!pos)
+ if (!pasid)
return -EINVAL;

- pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+ pci_read_config_word(pdev, pasid + PCI_PASID_CAP, &supported);

supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;

@@ -470,16 +470,15 @@ EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required);
int pci_max_pasids(struct pci_dev *pdev)
{
u16 supported;
- int pos;
+ int pasid = pdev->pasid_cap;

if (pdev->is_virtfn)
pdev = pci_physfn(pdev);

- pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
- if (!pos)
+ if (!pasid)
return -EINVAL;

- pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+ pci_read_config_word(pdev, pasid + PCI_PASID_CAP, &supported);

supported = (supported & PASID_NUMBER_MASK) >> PASID_NUMBER_SHIFT;

diff --git a/include/linux/pci.h b/include/linux/pci.h
index c81a24172b14..7ddbb6445e1a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -458,6 +458,7 @@ struct pci_dev {
u32 pri_reqs_alloc; /* Number of PRI requests allocated */
#endif
#ifdef CONFIG_PCI_PASID
+ u16 pasid_cap; /* PASID Capability offset */
u16 pasid_features;
#endif
#ifdef CONFIG_PCI_P2PDMA
--
2.23.0.187.g17f5b7556c-goog
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