PCIe spec 5.0 r1.0 section 2.2.6.2 says:
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_tags file to query the status of VF 10-Bit Tag
Requester Enable.
Add a sriov_vf_tags_ctl sysfs file, write 0 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. Write 10 to enable 10-Bit
Tag Requester when RC supports 10-Bit Tag Completer capability. The
typical use case is for host memory targeted by DMA Requests.
Signed-off-by: Dongdong Liu <liudongdong3@xxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-bus-pci | 32 +++++++++++
drivers/pci/iov.c | 70 +++++++++++++++++++++++++
2 files changed, 102 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index c16bb31486d2..9343941969b6 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -446,3 +446,35 @@ Description:
Write 10 to enable 10-Bit Tag Requester when RC supports 10-Bit
Tag Completer capability. The typical use case is for host
memory targeted by DMA Requests.
+
+What: /sys/bus/pci/devices/.../sriov_vf_tags
+Date: September 2021
+Contact: Dongdong Liu <liudongdong3@xxxxxxxxxx>
+Description:
+ This file is associated with a SR-IOV physical function (PF).
+ It is visible when the device supports VF 10-Bit Tag
+ Requester. It contains the status of VF Tags Enable.
+ The file is read-only.
+
+What: /sys/bus/pci/devices/.../sriov_vf_tags_ctl
+Date: September 2021
+Contact: Dongdong Liu <liudongdong3@xxxxxxxxxx>
+Description:
+ This file is associated with a SR-IOV virtual function (VF).
+ It is visible when the device supports VF 10-Bit Tag
+ Requester. The file is only writeable when the VF driver
+ does not bind to a device.
+
+ The values accepted are:
+ * > 0 - this number will be reported as tags bit to be
+ enabled. current only 10 is accepted
+ * < 0 - not valid
+ * = 0 - disable 10-Bit Tag, use Extended Tags(8-Bit or 5-Bit)
+
+ Write 0 to any VF's file disables 10-Bit Tag Requester for all
+ VFs. The typical use case is for p2pdma when the peer device
+ does not support 10-Bit Tag Completer.
+
+ Write 10 to enable 10-Bit Tag Requester for all VFs when RC
+ supports 10-Bit Tag Completer capability. The typical use case
+ is for host memory targeted by DMA Requests.
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index dafdc652fcd0..3627e495d7af 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -220,10 +220,47 @@ 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_tags_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);
+ unsigned long val;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (kstrtoul(buf, 0, &val) < 0)
+ return -EINVAL;
+
+ /* 10 - enable 10-Bit Tag, 0 - disable 10-Bit Tag */
+ if (val != 10 && val != 0)
+ return -EINVAL;
+
+ if (vf_dev->driver)
+ return -EBUSY;
+
+ if (!pcie_rp_10bit_tag_cmp_supported(pdev))
+ return -EPERM;
+
+ if (val == 10)
+ pdev->sriov->ctrl |= PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN;
+ else
+ pdev->sriov->ctrl &= ~PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN;
+
+ pci_write_config_word(pdev, pdev->sriov->pos + PCI_SRIOV_CTRL,
+ pdev->sriov->ctrl);
+
+ return count;
+}
+static DEVICE_ATTR_WO(sriov_vf_tags_ctl);
+
static struct attribute *sriov_vf_dev_attrs[] = {
#ifdef CONFIG_PCI_MSI
&dev_attr_sriov_vf_msix_count.attr,
#endif
+ &dev_attr_sriov_vf_tags_ctl.attr,
NULL,
};
@@ -236,6 +273,11 @@ 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_tags_ctl.attr) &&
+ !(pdev->sriov->cap & PCI_SRIOV_CAP_VF_10BIT_TAG_REQ))
+ return 0;
+
return a->mode;
}
@@ -487,12 +529,34 @@ static ssize_t sriov_drivers_autoprobe_store(struct device *dev,
return count;
}
+static ssize_t sriov_vf_tags_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ u16 ctl;
+ int ret;
+
+ if (pdev->sriov->ctrl & PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN)
+ return sysfs_emit(buf, "%s\n", "10-Bit");
+
+ ret = pcie_capability_read_word(pdev, PCI_EXP_DEVCTL, &ctl);
+ if (ret)
+ return -EINVAL;
+
+ if (ctl & PCI_EXP_DEVCTL_EXT_TAG)
+ return sysfs_emit(buf, "%s\n", "8-Bit");
+
+ return sysfs_emit(buf, "%s\n", "5-Bit");
+}
+
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_tags);
static struct attribute *sriov_pf_dev_attrs[] = {
&dev_attr_sriov_totalvfs.attr,
@@ -501,6 +565,7 @@ 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_tags.attr,
#ifdef CONFIG_PCI_MSI
&dev_attr_sriov_vf_total_msix.attr,
#endif
@@ -511,10 +576,15 @@ 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_tags.attr) &&
+ !(pdev->sriov->cap & PCI_SRIOV_CAP_VF_10BIT_TAG_REQ))
+ return 0;
+
return a->mode;
}
--
2.22.0
