From: Leon Romanovsky <leonro@xxxxxxxxxx>
This function is applicable for SR-IOV VFs because such devices allocate
their MSI-X table before they will run on the targeted hardware and they
can't guess the right amount of vectors.
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-bus-pci | 16 +++++++
drivers/pci/iov.c | 57 +++++++++++++++++++++++++
drivers/pci/msi.c | 30 +++++++++++++
drivers/pci/pci-sysfs.c | 1 +
drivers/pci/pci.h | 1 +
include/linux/pci.h | 8 ++++
6 files changed, 113 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 25c9c39770c6..30720a9e1386 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -375,3 +375,19 @@ Description:
The value comes from the PCI kernel device state and can be one
of: "unknown", "error", "D0", D1", "D2", "D3hot", "D3cold".
The file is read only.
+
+What: /sys/bus/pci/devices/.../vf_msix_vec
+Date: December 2020
+Contact: Leon Romanovsky <leonro@xxxxxxxxxx>
+Description:
+ This file is associated with the SR-IOV VFs. It allows overwrite
+ the amount of MSI-X vectors for that VF. This is needed to optimize
+ performance of newly bounded devices by allocating the number of
+ vectors based on the internal knowledge of targeted VM.
+
+ The values accepted are:
+ * > 0 - this will be number reported by the PCI VF's PCIe MSI-X capability.
+ * < 0 - not valid
+ * = 0 - will reset to the device default value
+
+ The file is writable if no driver is bounded.
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 4afd4ee4f7f0..0f8c570361fc 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -31,6 +31,7 @@ int pci_iov_virtfn_devfn(struct pci_dev *dev, int vf_id)
return (dev->devfn + dev->sriov->offset +
dev->sriov->stride * vf_id) & 0xff;
}
+EXPORT_SYMBOL(pci_iov_virtfn_devfn);
/*
* Per SR-IOV spec sec 3.3.10 and 3.3.11, First VF Offset and VF Stride may
@@ -426,6 +427,62 @@ const struct attribute_group sriov_dev_attr_group = {
.is_visible = sriov_attrs_are_visible,
};
+#ifdef CONFIG_PCI_MSI
+static ssize_t vf_msix_vec_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ int numb = pci_msix_vec_count(pdev);
+
+ if (numb < 0)
+ return numb;
+
+ return sprintf(buf, "%d\n", numb);
+}
+
+static ssize_t vf_msix_vec_store(struct device *dev,
+ struct device_attribute *attr, const char *buf,
+ size_t count)
+{
+ struct pci_dev *vf_dev = to_pci_dev(dev);
+ int val, ret;
+
+ ret = kstrtoint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ ret = pci_set_msix_vec_count(vf_dev, val);
+ if (ret)
+ return ret;
+
+ return count;
+}
+static DEVICE_ATTR_RW(vf_msix_vec);
+#endif
+
+static struct attribute *sriov_vf_dev_attrs[] = {
+#ifdef CONFIG_PCI_MSI
+ &dev_attr_vf_msix_vec.attr,
+#endif
+ NULL,
+};
+
+static umode_t sriov_vf_attrs_are_visible(struct kobject *kobj,
+ struct attribute *a, int n)
+{
+ struct device *dev = kobj_to_dev(kobj);
+
+ if (dev_is_pf(dev))
+ return 0;
+
+ return a->mode;
+}
+
+const struct attribute_group sriov_vf_dev_attr_group = {
+ .attrs = sriov_vf_dev_attrs,
+ .is_visible = sriov_vf_attrs_are_visible,
+};
+
int __weak pcibios_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
{
return 0;
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 3162f88fe940..0bcd705487d9 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -991,6 +991,36 @@ int pci_msix_vec_count(struct pci_dev *dev)
}
EXPORT_SYMBOL(pci_msix_vec_count);
+/**
+ * pci_set_msix_vec_count - change the reported number of MSI-X vectors.
+ * This function is applicable for SR-IOV VFs because such devices allocate
+ * their MSI-X table before they will run on the targeted hardware and they
+ * can't guess the right amount of vectors.
+ * @dev: VF device that is going to be changed.
+ * @numb: amount of MSI-X vectors.
+ **/
+int pci_set_msix_vec_count(struct pci_dev *dev, int numb)
+{
+ struct pci_dev *pdev = pci_physfn(dev);
+
+ if (!dev->msix_cap || !pdev->msix_cap)
+ return -EINVAL;
+
+ if (dev->driver || !pdev->driver ||
+ !pdev->driver->sriov_set_msix_vec_count)
+ return -EOPNOTSUPP;
+
+ if (numb < 0)
+ /*
+ * We don't support negative numbers for now,
+ * but maybe in the future it will make sense.
+ */
+ return -EINVAL;
+
+ return pdev->driver->sriov_set_msix_vec_count(dev, numb);
+}
+EXPORT_SYMBOL(pci_set_msix_vec_count);
+
static int __pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
int nvec, struct irq_affinity *affd, int flags)
{
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index fb072f4b3176..0af2222643c2 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1557,6 +1557,7 @@ static const struct attribute_group *pci_dev_attr_groups[] = {
&pci_dev_hp_attr_group,
#ifdef CONFIG_PCI_IOV
&sriov_dev_attr_group,
+ &sriov_vf_dev_attr_group,
#endif
&pci_bridge_attr_group,
&pcie_dev_attr_group,
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 5c59365092fa..46396a5da2d9 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -502,6 +502,7 @@ resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno);
void pci_restore_iov_state(struct pci_dev *dev);
int pci_iov_bus_range(struct pci_bus *bus);
extern const struct attribute_group sriov_dev_attr_group;
+extern const struct attribute_group sriov_vf_dev_attr_group;
#else
static inline int pci_iov_init(struct pci_dev *dev)
{
diff --git a/include/linux/pci.h b/include/linux/pci.h
index b32126d26997..1acba40a1b1b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -856,6 +856,8 @@ struct module;
* e.g. drivers/net/e100.c.
* @sriov_configure: Optional driver callback to allow configuration of
* number of VFs to enable via sysfs "sriov_numvfs" file.
+ * @sriov_set_msix_vec_count: Driver callback to change number of MSI-X vectors
+ * exposed by the sysfs "vf_msix_vec" entry.
* @err_handler: See Documentation/PCI/pci-error-recovery.rst
* @groups: Sysfs attribute groups.
* @driver: Driver model structure.
@@ -871,6 +873,7 @@ struct pci_driver {
int (*resume)(struct pci_dev *dev); /* Device woken up */
void (*shutdown)(struct pci_dev *dev);
int (*sriov_configure)(struct pci_dev *dev, int num_vfs); /* On PF */
+ int (*sriov_set_msix_vec_count)(struct pci_dev *vf, int msix_vec_count); /* On PF */
const struct pci_error_handlers *err_handler;
const struct attribute_group **groups;
struct device_driver driver;
@@ -1464,6 +1467,7 @@ struct msix_entry {
int pci_msi_vec_count(struct pci_dev *dev);
void pci_disable_msi(struct pci_dev *dev);
int pci_msix_vec_count(struct pci_dev *dev);
+int pci_set_msix_vec_count(struct pci_dev *dev, int numb);
void pci_disable_msix(struct pci_dev *dev);
void pci_restore_msi_state(struct pci_dev *dev);
int pci_msi_enabled(void);
@@ -2402,6 +2406,10 @@ static inline bool pci_is_thunderbolt_attached(struct pci_dev *pdev)
void pci_uevent_ers(struct pci_dev *pdev, enum pci_ers_result err_type);
#endif
+#ifdef CONFIG_PCI_IOV
+int pci_iov_virtfn_devfn(struct pci_dev *dev, int vf_id);
+#endif
+
/* Provide the legacy pci_dma_* API */
#include <linux/pci-dma-compat.h>
--
2.29.2
