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Date: Wed, 4 Aug 2021 21:47:06 +0800
From: Dongdong Liu <liudongdong3@...wei.com>
To: <helgaas@...nel.org>, <hch@...radead.org>, <kw@...ux.com>,
<logang@...tatee.com>, <leon@...nel.org>,
<linux-pci@...r.kernel.org>, <rajur@...lsio.com>,
<hverkuil-cisco@...all.nl>
CC: <linux-media@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: [PATCH V7 7/9] PCI/sysfs: Add a 10-Bit Tag sysfs file
PCIe spec 5.0 r1.0 section 2.2.6.2 says that if an Endpoint supports
sending Requests to other Endpoints (as opposed to host memory), the
Endpoint must not send 10-Bit Tag Requests to another given Endpoint
unless an implementation-specific mechanism determines that the Endpoint
supports 10-Bit Tag Completer capability. Add a 10bit_tag sysfs file,
write 0 to disable 10-Bit Tag Requester when the driver does not bind
the device if the peer device does not support the 10-Bit Tag Completer.
This will make P2P traffic safe. the 10bit_tag file content indicate
current 10-Bit Tag Requester Enable status.
Signed-off-by: Dongdong Liu <liudongdong3@...wei.com>
---
Documentation/ABI/testing/sysfs-bus-pci | 16 +++++++-
drivers/pci/pci-sysfs.c | 69 +++++++++++++++++++++++++++++++++
2 files changed, 84 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 793cbb7..0e0c97d 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -139,7 +139,7 @@ Description:
binary file containing the Vital Product Data for the
device. It should follow the VPD format defined in
PCI Specification 2.1 or 2.2, but users should consider
- that some devices may have incorrectly formatted data.
+ that some devices may have incorrectly formatted data.
If the underlying VPD has a writable section then the
corresponding section of this file will be writable.
@@ -407,3 +407,17 @@ Description:
The file is writable if the PF is bound to a driver that
implements ->sriov_set_msix_vec_count().
+
+What: /sys/bus/pci/devices/.../10bit_tag
+Date: August 2021
+Contact: Dongdong Liu <liudongdong3@...wei.com>
+Description:
+ If a PCI device support 10-Bit Tag Requester, will create the
+ 10bit_tag sysfs file. The file is readable, the value
+ indicate current 10-Bit Tag Requester Enable.
+ 1 - enabled, 0 - disabled.
+
+ The file is also writeable, the value only accept by write 0
+ to disable 10-Bit Tag Requester when the driver does not bind
+ the deivce. The typical use case is for p2pdma when the peer
+ device does not support 10-BIT Tag Completer.
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 5d63df7..e93ce8b 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -306,6 +306,49 @@ static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RW(enable);
+static ssize_t pci_10bit_tag_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ bool enable;
+
+ if (kstrtobool(buf, &enable) < 0)
+ return -EINVAL;
+
+ if (enable != false )
+ return -EINVAL;
+
+ if (pdev->driver)
+ return -EBUSY;
+
+ pcie_capability_clear_word(pdev, PCI_EXP_DEVCTL2,
+ PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN);
+ pci_info(pdev, "disabled 10-Bit Tag Requester\n");
+
+ return count;
+}
+
+static ssize_t pci_10bit_tag_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ u16 ctl;
+ int ret;
+
+ ret = pcie_capability_read_word(pdev, PCI_EXP_DEVCTL2, &ctl);
+ if (ret)
+ return -EINVAL;
+
+ return sysfs_emit(buf, "%u\n",
+ !!(ctl & PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN));
+}
+
+static struct device_attribute dev_attr_10bit_tag = __ATTR(10bit_tag, 0600,
+ pci_10bit_tag_show,
+ pci_10bit_tag_store);
+
#ifdef CONFIG_NUMA
static ssize_t numa_node_store(struct device *dev,
struct device_attribute *attr, const char *buf,
@@ -635,6 +678,11 @@ static struct attribute *pcie_dev_attrs[] = {
NULL,
};
+static struct attribute *pcie_dev_10bit_tag_attrs[] = {
+ &dev_attr_10bit_tag.attr,
+ NULL,
+};
+
static struct attribute *pcibus_attrs[] = {
&dev_attr_bus_rescan.attr,
&dev_attr_cpuaffinity.attr,
@@ -1482,6 +1530,21 @@ static umode_t pcie_dev_attrs_are_visible(struct kobject *kobj,
return 0;
}
+static umode_t pcie_dev_10bit_tag_attrs_are_visible(struct kobject *kobj,
+ struct attribute *a, int n)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct pci_dev *pdev = to_pci_dev(dev);
+
+ if (pdev->is_virtfn)
+ return 0;
+
+ if (!(pdev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_REQ))
+ return 0;
+
+ return a->mode;
+}
+
static const struct attribute_group pci_dev_group = {
.attrs = pci_dev_attrs,
};
@@ -1521,6 +1584,11 @@ static const struct attribute_group pcie_dev_attr_group = {
.is_visible = pcie_dev_attrs_are_visible,
};
+static const struct attribute_group pcie_dev_10bit_tag_attr_group = {
+ .attrs = pcie_dev_10bit_tag_attrs,
+ .is_visible = pcie_dev_10bit_tag_attrs_are_visible,
+};
+
static const struct attribute_group *pci_dev_attr_groups[] = {
&pci_dev_attr_group,
&pci_dev_hp_attr_group,
@@ -1530,6 +1598,7 @@ static const struct attribute_group *pci_dev_attr_groups[] = {
#endif
&pci_bridge_attr_group,
&pcie_dev_attr_group,
+ &pcie_dev_10bit_tag_attr_group,
#ifdef CONFIG_PCIEAER
&aer_stats_attr_group,
#endif
--
2.7.4
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