[PATCH V7 8/9] PCI/IOV: Add 10-Bit Tag sysfs files for VF devices

Dongdong Liu
2021-08-04T13:49:41Z

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 sriov_vf_10bit_tag file to query the status of VF 10-Bit Tag
Requester Enable. Add sriov_vf_10bit_tag_ctl file to disable the VF
10-Bit Tag Requester. The typical use case is for p2pdma when the peer
device does not support 10-BIT Tag Completer.

Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
---
Documentation/ABI/testing/sysfs-bus-pci | 20 +++++++++++++
drivers/pci/iov.c | 50 +++++++++++++++++++++++++++++++++
2 files changed, 70 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 0e0c97d..8fdbfae 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -421,3 +421,23 @@ Description:
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.
+
+What: /sys/bus/pci/devices/.../sriov_vf_10bit_tag
+Date: August 2021
+Contact: Dongdong Liu <liudongdong3@huawei.com>
+Description:
+ This file is associated with a SR-IOV physical function (PF).
+ It is visible when the device has VF 10-Bit Tag Requester
+ Supported. It contains the status of VF 10-Bit Tag Requester
+ Enable. The file is only readable.
+
+What: /sys/bus/pci/devices/.../sriov_vf_10bit_tag_ctl
+Date: August 2021
+Contact: Dongdong Liu <liudongdong3@huawei.com>
+Description:
+ This file is associated with a SR-IOV virtual function (VF).
+ It is visible when the device has VF 10-Bit Tag Requester
+ Supported. It only allows to write 0 to disable VF 10-Bit
+ Tag Requester. The file is only writeable when the vf driver
+ does not bind to a dirver. The typical use case is for p2pdma
+ when the peer device does not support 10-BIT Tag Completer.
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 0d0bed1..04c1298 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -220,10 +220,38 @@ static ssize_t sriov_vf_msix_count_store(struct device *dev,
static DEVICE_ATTR_WO(sriov_vf_msix_count);
#endif

+static ssize_t sriov_vf_10bit_tag_ctl_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct pci_dev *vf_dev = to_pci_dev(dev);
+ struct pci_dev *pdev = pci_physfn(vf_dev);
+ struct pci_sriov *iov;
+ bool enable;
+
+ if (kstrtobool(buf, &enable) < 0)
+ return -EINVAL;
+
+ if (enable != false)
+ return -EINVAL;
+
+ if (vf_dev->driver)
+ return -EBUSY;
+
+ iov = pdev->sriov;
+ iov->ctrl &= ~PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN;
+ pci_write_config_word(pdev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
+ pci_info(pdev, "disabled SRIOV 10-Bit Tag Requester\n");
+
+ return count;
+}
+static DEVICE_ATTR_WO(sriov_vf_10bit_tag_ctl);
+
static struct attribute *sriov_vf_dev_attrs[] = {
#ifdef CONFIG_PCI_MSI
&dev_attr_sriov_vf_msix_count.attr,
#endif
+ &dev_attr_sriov_vf_10bit_tag_ctl.attr,
NULL,
};

@@ -236,6 +264,11 @@ static umode_t sriov_vf_attrs_are_visible(struct kobject *kobj,
if (!pdev->is_virtfn)
return 0;

+ pdev = pci_physfn(pdev);
+ if ((a == &dev_attr_sriov_vf_10bit_tag_ctl.attr) &&
+ !(pdev->sriov->cap & PCI_SRIOV_CAP_VF_10BIT_TAG_REQ))
+ return 0;
+
return a->mode;
}

@@ -487,12 +520,23 @@ static ssize_t sriov_drivers_autoprobe_store(struct device *dev,
return count;
}

+static ssize_t sriov_vf_10bit_tag_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+
+ return sysfs_emit(buf, "%u\n",
+ !!(pdev->sriov->ctrl & PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN));
+}
+
static DEVICE_ATTR_RO(sriov_totalvfs);
static DEVICE_ATTR_RW(sriov_numvfs);
static DEVICE_ATTR_RO(sriov_offset);
static DEVICE_ATTR_RO(sriov_stride);
static DEVICE_ATTR_RO(sriov_vf_device);
static DEVICE_ATTR_RW(sriov_drivers_autoprobe);
+static DEVICE_ATTR_RO(sriov_vf_10bit_tag);

static struct attribute *sriov_pf_dev_attrs[] = {
&dev_attr_sriov_totalvfs.attr,
@@ -501,6 +545,7 @@ static struct attribute *sriov_pf_dev_attrs[] = {
&dev_attr_sriov_stride.attr,
&dev_attr_sriov_vf_device.attr,
&dev_attr_sriov_drivers_autoprobe.attr,
+ &dev_attr_sriov_vf_10bit_tag.attr,
#ifdef CONFIG_PCI_MSI
&dev_attr_sriov_vf_total_msix.attr,
#endif
@@ -511,10 +556,15 @@ static umode_t sriov_pf_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 (!dev_is_pf(dev))
return 0;

+ if ((a == &dev_attr_sriov_vf_10bit_tag.attr) &&
+ !(pdev->sriov->cap & PCI_SRIOV_CAP_VF_10BIT_TAG_REQ))
+ return 0;
+
return a->mode;
}

--
2.7.4