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Subject[PATCH v7 3/7] PCI/ATS: Cache PASID capability check result
Date
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

Currently, PASID capability checks are repeated across all PASID API's.
Instead, cache the capability check result in pci_pasid_init() and use
it in other PASID API's.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
drivers/pci/ats.c | 50 ++++++++++++++++++++++++++-------------------
include/linux/pci.h | 1 +
2 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index b863562b6702..022698a85c98 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -29,6 +29,19 @@ static void pci_pri_init(struct pci_dev *pdev)
#endif
}

+static void pci_pasid_init(struct pci_dev *pdev)
+{
+#ifdef CONFIG_PCI_PASID
+ int pos;
+
+ pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
+ if (!pos)
+ return;
+
+ pdev->pasid_cap = pos;
+#endif
+}
+
void pci_ats_init(struct pci_dev *dev)
{
int pos;
@@ -43,6 +56,8 @@ void pci_ats_init(struct pci_dev *dev)
dev->ats_cap = pos;

pci_pri_init(dev);
+
+ pci_pasid_init(dev);
}

/**
@@ -303,7 +318,6 @@ EXPORT_SYMBOL_GPL(pci_reset_pri);
int pci_enable_pasid(struct pci_dev *pdev, int features)
{
u16 control, supported;
- int pos;

if (WARN_ON(pdev->pasid_enabled))
return -EBUSY;
@@ -311,11 +325,11 @@ 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)
+ if (!pdev->pasid_cap)
return -EINVAL;

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

/* User wants to enable anything unsupported? */
@@ -325,7 +339,7 @@ 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, pdev->pasid_cap + PCI_PASID_CTRL, control);

pdev->pasid_enabled = 1;

@@ -340,16 +354,14 @@ EXPORT_SYMBOL_GPL(pci_enable_pasid);
void pci_disable_pasid(struct pci_dev *pdev)
{
u16 control = 0;
- int pos;

if (WARN_ON(!pdev->pasid_enabled))
return;

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

- pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+ pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control);

pdev->pasid_enabled = 0;
}
@@ -362,17 +374,15 @@ EXPORT_SYMBOL_GPL(pci_disable_pasid);
void pci_restore_pasid_state(struct pci_dev *pdev)
{
u16 control;
- int pos;

if (!pdev->pasid_enabled)
return;

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

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

@@ -389,13 +399,12 @@ EXPORT_SYMBOL_GPL(pci_restore_pasid_state);
int pci_pasid_features(struct pci_dev *pdev)
{
u16 supported;
- int pos;

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

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

supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;

@@ -445,13 +454,12 @@ EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required);
int pci_max_pasids(struct pci_dev *pdev)
{
u16 supported;
- int pos;

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

- pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+ pci_read_config_word(pdev, pdev->pasid_cap + 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 79991984c4cd..782bca667010 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -459,6 +459,7 @@ 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
--
2.21.0
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