| Message ID | 20210314124256.70253-2-leon@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | Dynamically assign MSI-X vectors count | expand |
Possible subject, since this adds *two* files, not just "a file": PCI/IOV: Add sysfs MSI-X vector assignment interface On Sun, Mar 14, 2021 at 02:42:53PM +0200, Leon Romanovsky wrote: > A typical cloud provider SR-IOV use case is to create many VFs for use by > guest VMs. The VFs may not be assigned to a VM until a customer requests a > VM of a certain size, e.g., number of CPUs. A VF may need MSI-X vectors > proportional to the number of CPUs in the VM, but there is no standard way > to change the number of MSI-X vectors supported by a VF. > ... > +#ifdef CONFIG_PCI_MSI > +static ssize_t sriov_vf_msix_count_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); > + int val, ret; > + > + ret = kstrtoint(buf, 0, &val); > + if (ret) > + return ret; > + > + if (val < 0) > + return -EINVAL; > + > + device_lock(&pdev->dev); > + if (!pdev->driver || !pdev->driver->sriov_set_msix_vec_count) { > + ret = -EOPNOTSUPP; > + goto err_pdev; > + } > + > + device_lock(&vf_dev->dev); > + if (vf_dev->driver) { > + /* > + * A driver is already attached to this VF and has configured > + * itself based on the current MSI-X vector count. Changing > + * the vector size could mess up the driver, so block it. > + */ > + ret = -EBUSY; > + goto err_dev; > + } > + > + ret = pdev->driver->sriov_set_msix_vec_count(vf_dev, val); > + > +err_dev: > + device_unlock(&vf_dev->dev); > +err_pdev: > + device_unlock(&pdev->dev); > + return ret ? : count; > +} > +static DEVICE_ATTR_WO(sriov_vf_msix_count); > + > +static ssize_t sriov_vf_total_msix_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct pci_dev *pdev = to_pci_dev(dev); > + u32 vf_total_msix = 0; > + > + device_lock(dev); > + if (!pdev->driver || !pdev->driver->sriov_get_vf_total_msix) > + goto unlock; > + > + vf_total_msix = pdev->driver->sriov_get_vf_total_msix(pdev); > +unlock: > + device_unlock(dev); > + return sysfs_emit(buf, "%u\n", vf_total_msix); > +} > +static DEVICE_ATTR_RO(sriov_vf_total_msix); Can you reverse the order of sriov_vf_total_msix_show() and sriov_vf_msix_count_store()? Currently we have: VF stuff (msix_count_store) PF stuff (total_msix) more VF stuff related to the above (vf_dev_attrs, are_visible) so the total_msix bit is mixed in the middle. > +#endif > + > +static struct attribute *sriov_vf_dev_attrs[] = { > +#ifdef CONFIG_PCI_MSI > + &dev_attr_sriov_vf_msix_count.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); > + struct pci_dev *pdev = to_pci_dev(dev); > + > + if (!pdev->is_virtfn) > + 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 pci_iov_add_virtfn(struct pci_dev *dev, int id) > { > int i; > @@ -400,18 +487,21 @@ static DEVICE_ATTR_RO(sriov_stride); > static DEVICE_ATTR_RO(sriov_vf_device); > static DEVICE_ATTR_RW(sriov_drivers_autoprobe); > > -static struct attribute *sriov_dev_attrs[] = { > +static struct attribute *sriov_pf_dev_attrs[] = { This and the related sriov_pf_attrs_are_visible change below are nice. Would you mind splitting them to a preliminary patch, since they really aren't related to the concept of *this* patch? > &dev_attr_sriov_totalvfs.attr, > &dev_attr_sriov_numvfs.attr, > &dev_attr_sriov_offset.attr, > &dev_attr_sriov_stride.attr, > &dev_attr_sriov_vf_device.attr, > &dev_attr_sriov_drivers_autoprobe.attr, > +#ifdef CONFIG_PCI_MSI > + &dev_attr_sriov_vf_total_msix.attr, > +#endif > NULL, > }; > > -static umode_t sriov_attrs_are_visible(struct kobject *kobj, > - struct attribute *a, int n) > +static umode_t sriov_pf_attrs_are_visible(struct kobject *kobj, > + struct attribute *a, int n) > { > struct device *dev = kobj_to_dev(kobj); > > @@ -421,9 +511,9 @@ static umode_t sriov_attrs_are_visible(struct kobject *kobj, > return a->mode; > } > > -const struct attribute_group sriov_dev_attr_group = { > - .attrs = sriov_dev_attrs, > - .is_visible = sriov_attrs_are_visible, > +const struct attribute_group sriov_pf_dev_attr_group = { > + .attrs = sriov_pf_dev_attrs, > + .is_visible = sriov_pf_attrs_are_visible, > };
On Fri, Apr 02, 2021 at 07:24:26PM -0500, Bjorn Helgaas wrote: > Possible subject, since this adds *two* files, not just "a file": > > PCI/IOV: Add sysfs MSI-X vector assignment interface Sure > > On Sun, Mar 14, 2021 at 02:42:53PM +0200, Leon Romanovsky wrote: > > A typical cloud provider SR-IOV use case is to create many VFs for use by > > guest VMs. The VFs may not be assigned to a VM until a customer requests a > > VM of a certain size, e.g., number of CPUs. A VF may need MSI-X vectors > > proportional to the number of CPUs in the VM, but there is no standard way > > to change the number of MSI-X vectors supported by a VF. > > ... > > > +#ifdef CONFIG_PCI_MSI > > +static ssize_t sriov_vf_msix_count_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); > > + int val, ret; > > + > > + ret = kstrtoint(buf, 0, &val); > > + if (ret) > > + return ret; > > + > > + if (val < 0) > > + return -EINVAL; > > + > > + device_lock(&pdev->dev); > > + if (!pdev->driver || !pdev->driver->sriov_set_msix_vec_count) { > > + ret = -EOPNOTSUPP; > > + goto err_pdev; > > + } > > + > > + device_lock(&vf_dev->dev); > > + if (vf_dev->driver) { > > + /* > > + * A driver is already attached to this VF and has configured > > + * itself based on the current MSI-X vector count. Changing > > + * the vector size could mess up the driver, so block it. > > + */ > > + ret = -EBUSY; > > + goto err_dev; > > + } > > + > > + ret = pdev->driver->sriov_set_msix_vec_count(vf_dev, val); > > + > > +err_dev: > > + device_unlock(&vf_dev->dev); > > +err_pdev: > > + device_unlock(&pdev->dev); > > + return ret ? : count; > > +} > > +static DEVICE_ATTR_WO(sriov_vf_msix_count); > > + > > +static ssize_t sriov_vf_total_msix_show(struct device *dev, > > + struct device_attribute *attr, > > + char *buf) > > +{ > > + struct pci_dev *pdev = to_pci_dev(dev); > > + u32 vf_total_msix = 0; > > + > > + device_lock(dev); > > + if (!pdev->driver || !pdev->driver->sriov_get_vf_total_msix) > > + goto unlock; > > + > > + vf_total_msix = pdev->driver->sriov_get_vf_total_msix(pdev); > > +unlock: > > + device_unlock(dev); > > + return sysfs_emit(buf, "%u\n", vf_total_msix); > > +} > > +static DEVICE_ATTR_RO(sriov_vf_total_msix); > > Can you reverse the order of sriov_vf_total_msix_show() and > sriov_vf_msix_count_store()? Currently we have: > > VF stuff (msix_count_store) > PF stuff (total_msix) > more VF stuff related to the above (vf_dev_attrs, are_visible) > > so the total_msix bit is mixed in the middle. No problem, I'll do. > > > +#endif > > + > > +static struct attribute *sriov_vf_dev_attrs[] = { > > +#ifdef CONFIG_PCI_MSI > > + &dev_attr_sriov_vf_msix_count.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); > > + struct pci_dev *pdev = to_pci_dev(dev); > > + > > + if (!pdev->is_virtfn) > > + 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 pci_iov_add_virtfn(struct pci_dev *dev, int id) > > { > > int i; > > @@ -400,18 +487,21 @@ static DEVICE_ATTR_RO(sriov_stride); > > static DEVICE_ATTR_RO(sriov_vf_device); > > static DEVICE_ATTR_RW(sriov_drivers_autoprobe); > > > > -static struct attribute *sriov_dev_attrs[] = { > > +static struct attribute *sriov_pf_dev_attrs[] = { > > This and the related sriov_pf_attrs_are_visible change below are nice. > Would you mind splitting them to a preliminary patch, since they > really aren't related to the concept of *this* patch? I don't think so, that prepatch will have only two lines of renames from sriov_dev_attrs to be sriov_pf_dev_attrs. It is not worth the hassle. Thanks > > > &dev_attr_sriov_totalvfs.attr, > > &dev_attr_sriov_numvfs.attr, > > &dev_attr_sriov_offset.attr, > > &dev_attr_sriov_stride.attr, > > &dev_attr_sriov_vf_device.attr, > > &dev_attr_sriov_drivers_autoprobe.attr, > > +#ifdef CONFIG_PCI_MSI > > + &dev_attr_sriov_vf_total_msix.attr, > > +#endif > > NULL, > > }; > > > > -static umode_t sriov_attrs_are_visible(struct kobject *kobj, > > - struct attribute *a, int n) > > +static umode_t sriov_pf_attrs_are_visible(struct kobject *kobj, > > + struct attribute *a, int n) > > { > > struct device *dev = kobj_to_dev(kobj); > > > > @@ -421,9 +511,9 @@ static umode_t sriov_attrs_are_visible(struct kobject *kobj, > > return a->mode; > > } > > > > -const struct attribute_group sriov_dev_attr_group = { > > - .attrs = sriov_dev_attrs, > > - .is_visible = sriov_attrs_are_visible, > > +const struct attribute_group sriov_pf_dev_attr_group = { > > + .attrs = sriov_pf_dev_attrs, > > + .is_visible = sriov_pf_attrs_are_visible, > > };
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 25c9c39770c6..606eec8ae4eb 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -375,3 +375,32 @@ 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/.../sriov_vf_total_msix +Date: January 2021 +Contact: Leon Romanovsky <leonro@nvidia.com> +Description: + This file is associated with a SR-IOV physical function (PF). + It contains the total number of MSI-X vectors available for + assignment to all virtual functions (VFs) associated with PF. + The value will be zero if the device doesn't support this + functionality. For supported devices, the value will be + constant and won't be changed after MSI-X vectors assignment. + +What: /sys/bus/pci/devices/.../sriov_vf_msix_count +Date: January 2021 +Contact: Leon Romanovsky <leonro@nvidia.com> +Description: + This file is associated with a SR-IOV virtual function (VF). + It allows configuration of the number of MSI-X vectors for + the VF. This allows devices that have a global pool of MSI-X + vectors to optimally divide them between VFs based on VF usage. + + The values accepted are: + * > 0 - this number will be reported as the Table Size in the + VF's MSI-X capability + * < 0 - not valid + * = 0 - will reset to the device default value + + The file is writable if the PF is bound to a driver that + implements ->sriov_set_msix_vec_count(). diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 4afd4ee4f7f0..9bf6f52ad4d8 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_GPL(pci_iov_virtfn_devfn); /* * Per SR-IOV spec sec 3.3.10 and 3.3.11, First VF Offset and VF Stride may @@ -157,6 +158,92 @@ int pci_iov_sysfs_link(struct pci_dev *dev, return rc; } +#ifdef CONFIG_PCI_MSI +static ssize_t sriov_vf_msix_count_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); + int val, ret; + + ret = kstrtoint(buf, 0, &val); + if (ret) + return ret; + + if (val < 0) + return -EINVAL; + + device_lock(&pdev->dev); + if (!pdev->driver || !pdev->driver->sriov_set_msix_vec_count) { + ret = -EOPNOTSUPP; + goto err_pdev; + } + + device_lock(&vf_dev->dev); + if (vf_dev->driver) { + /* + * A driver is already attached to this VF and has configured + * itself based on the current MSI-X vector count. Changing + * the vector size could mess up the driver, so block it. + */ + ret = -EBUSY; + goto err_dev; + } + + ret = pdev->driver->sriov_set_msix_vec_count(vf_dev, val); + +err_dev: + device_unlock(&vf_dev->dev); +err_pdev: + device_unlock(&pdev->dev); + return ret ? : count; +} +static DEVICE_ATTR_WO(sriov_vf_msix_count); + +static ssize_t sriov_vf_total_msix_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct pci_dev *pdev = to_pci_dev(dev); + u32 vf_total_msix = 0; + + device_lock(dev); + if (!pdev->driver || !pdev->driver->sriov_get_vf_total_msix) + goto unlock; + + vf_total_msix = pdev->driver->sriov_get_vf_total_msix(pdev); +unlock: + device_unlock(dev); + return sysfs_emit(buf, "%u\n", vf_total_msix); +} +static DEVICE_ATTR_RO(sriov_vf_total_msix); +#endif + +static struct attribute *sriov_vf_dev_attrs[] = { +#ifdef CONFIG_PCI_MSI + &dev_attr_sriov_vf_msix_count.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); + struct pci_dev *pdev = to_pci_dev(dev); + + if (!pdev->is_virtfn) + 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 pci_iov_add_virtfn(struct pci_dev *dev, int id) { int i; @@ -400,18 +487,21 @@ static DEVICE_ATTR_RO(sriov_stride); static DEVICE_ATTR_RO(sriov_vf_device); static DEVICE_ATTR_RW(sriov_drivers_autoprobe); -static struct attribute *sriov_dev_attrs[] = { +static struct attribute *sriov_pf_dev_attrs[] = { &dev_attr_sriov_totalvfs.attr, &dev_attr_sriov_numvfs.attr, &dev_attr_sriov_offset.attr, &dev_attr_sriov_stride.attr, &dev_attr_sriov_vf_device.attr, &dev_attr_sriov_drivers_autoprobe.attr, +#ifdef CONFIG_PCI_MSI + &dev_attr_sriov_vf_total_msix.attr, +#endif NULL, }; -static umode_t sriov_attrs_are_visible(struct kobject *kobj, - struct attribute *a, int n) +static umode_t sriov_pf_attrs_are_visible(struct kobject *kobj, + struct attribute *a, int n) { struct device *dev = kobj_to_dev(kobj); @@ -421,9 +511,9 @@ static umode_t sriov_attrs_are_visible(struct kobject *kobj, return a->mode; } -const struct attribute_group sriov_dev_attr_group = { - .attrs = sriov_dev_attrs, - .is_visible = sriov_attrs_are_visible, +const struct attribute_group sriov_pf_dev_attr_group = { + .attrs = sriov_pf_dev_attrs, + .is_visible = sriov_pf_attrs_are_visible, }; int __weak pcibios_sriov_enable(struct pci_dev *pdev, u16 num_vfs) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index f8afd54ca3e1..a6b8fbbba6d2 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1567,7 +1567,8 @@ static const struct attribute_group *pci_dev_attr_groups[] = { &pci_dev_attr_group, &pci_dev_hp_attr_group, #ifdef CONFIG_PCI_IOV - &sriov_dev_attr_group, + &sriov_pf_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 ef7c4661314f..afb87b917f07 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -501,7 +501,8 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno); 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_pf_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 86c799c97b77..9b575a676888 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -856,6 +856,12 @@ 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: PF Driver callback to change number of MSI-X + * vectors on a VF. Triggered via sysfs "sriov_vf_msix_count". + * This will change MSI-X Table Size in the VF Message Control + * registers. + * @sriov_get_vf_total_msix: PF driver callback to get the total number of + * MSI-X vectors available for distribution to the VFs. * @err_handler: See Documentation/PCI/pci-error-recovery.rst * @groups: Sysfs attribute groups. * @driver: Driver model structure. @@ -871,6 +877,8 @@ 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 */ + u32 (*sriov_get_vf_total_msix)(struct pci_dev *pf); const struct pci_error_handlers *err_handler; const struct attribute_group **groups; struct device_driver driver;
A typical cloud provider SR-IOV use case is to create many VFs for use by guest VMs. The VFs may not be assigned to a VM until a customer requests a VM of a certain size, e.g., number of CPUs. A VF may need MSI-X vectors proportional to the number of CPUs in the VM, but there is no standard way to change the number of MSI-X vectors supported by a VF. Some Mellanox ConnectX devices support dynamic assignment of MSI-X vectors to SR-IOV VFs. This can be done by the PF driver after VFs are enabled, and it can be done without affecting VFs that are already in use. The hardware supports a limited pool of MSI-X vectors that can be assigned to the PF or to individual VFs. This is device-specific behavior that requires support in the PF driver. Add a read-only "sriov_vf_total_msix" sysfs file for the PF and a writable "sriov_vf_msix_count" file for each VF. Management software may use these to learn how many MSI-X vectors are available and to dynamically assign them to VFs before the VFs are passed through to a VM. If the PF driver implements the ->sriov_get_vf_total_msix() callback, "sriov_vf_total_msix" contains the total number of MSI-X vectors available for distribution among VFs. If no driver is bound to the VF, writing "N" to "sriov_vf_msix_count" uses the PF driver ->sriov_set_msix_vec_count() callback to assign "N" MSI-X vectors to the VF. When a VF driver subsequently reads the MSI-X Message Control register, it will see the new Table Size "N". Signed-off-by: Leon Romanovsky <leonro@nvidia.com> --- Documentation/ABI/testing/sysfs-bus-pci | 29 +++++++ drivers/pci/iov.c | 102 ++++++++++++++++++++++-- drivers/pci/pci-sysfs.c | 3 +- drivers/pci/pci.h | 3 +- include/linux/pci.h | 8 ++ 5 files changed, 137 insertions(+), 8 deletions(-) -- 2.30.2