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Subject[PATCH v4 3/7] PCI/ATS: Initialize PASID in pci_ats_init()
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. Also, since PASID is a shared resource between
PF/VF, initialize PASID features with default values in pci_pasid_init().

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
drivers/pci/ats.c | 76 ++++++++++++++++++++++++++++++++-------------
include/linux/pci.h | 1 +
2 files changed, 56 insertions(+), 21 deletions(-)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index a14ab20f1c28..b5ce40c54e0b 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -50,6 +50,41 @@ static void pci_pri_init(struct pci_dev *pdev)
}
#endif

+#ifdef CONFIG_PCI_PASID
+static void pci_pasid_init(struct pci_dev *pdev)
+{
+ u16 supported;
+ int pos;
+
+ /*
+ * As per PCIe r4.0, sec 9.3.7.14, only PF is permitted to
+ * implement PASID Capability and all associated VFs can
+ * only use it. Since PF already initialized the PASID
+ * parameters there is no need to proceed further.
+ */
+ if (pdev->is_virtfn)
+ return;
+
+ pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
+ if (!pos)
+ return;
+
+ pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+
+ supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
+
+ /*
+ * Enable all supported features. Since PASID is a shared
+ * resource between PF/VF, we must not set this feature as
+ * a per device property in pci_enable_pasid().
+ */
+ pci_write_config_word(pdev, pos + PCI_PASID_CTRL, supported);
+
+ pdev->pasid_features = supported;
+ pdev->pasid_cap = pos;
+}
+#endif
+
void pci_ats_init(struct pci_dev *dev)
{
int pos;
@@ -66,6 +101,9 @@ void pci_ats_init(struct pci_dev *dev)
#ifdef CONFIG_PCI_PRI
pci_pri_init(dev);
#endif
+#ifdef CONFIG_PCI_PASID
+ pci_pasid_init(dev);
+#endif
}

/**
@@ -326,11 +364,13 @@ EXPORT_SYMBOL_GPL(pci_reset_pri);
* Returns 0 on success, negative value on error. This function checks
* whether the features are actually supported by the device and returns
* an error if not.
+ *
+ * TODO: Since PASID is a shared resource between PF/VF, don't update
+ * PASID features in the same API as a per device feature.
*/
int pci_enable_pasid(struct pci_dev *pdev, int features)
{
u16 control, supported;
- int pos;

if (WARN_ON(pdev->pasid_enabled))
return -EBUSY;
@@ -338,11 +378,11 @@ 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? */
@@ -352,7 +392,7 @@ 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;

@@ -367,16 +407,14 @@ 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;
}
@@ -389,17 +427,15 @@ 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);

@@ -416,13 +452,12 @@ 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;

@@ -472,13 +507,12 @@ 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 f3fe625bc8bb..b4010276dff6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -456,6 +456,7 @@ 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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