* How to get the number of VFs assigned to the guests in XEN @ 2014-08-20 11:09 Sreekanth Reddy 2014-08-20 12:46 ` Alex Williamson 0 siblings, 1 reply; 6+ messages in thread From: Sreekanth Reddy @ 2014-08-20 11:09 UTC (permalink / raw) To: linux-scsi, linux-kernel, linux-pci, konrad.wilk Cc: Martin K. Petersen, Christoph Hellwig, boris.ostrovsky, Sathya Prakash, Nagalakshmi Nandigama HI, For SRIOV support, currently in the KVM environment, mpt3sas driver can use the API pci_vfs_assigned() to know the number of VFs that are currently assigned to the running VMs. So that during the PF driver unload time, if the return value of this API is greater than zero the our driver won't call the pci_disable_sriov() to disable the VFs. Now for the same purpose in XEN environment, is there any API similar to pci_vfs_assigned() which the low lever device driver can use to know 'the number of VFs that are currently assigned to the running VMs'. In XEN environment this API pci_vfs_assigned() will return always zero even though VFs are assigned to the running VMs. Regards, Sreekanth ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How to get the number of VFs assigned to the guests in XEN 2014-08-20 11:09 How to get the number of VFs assigned to the guests in XEN Sreekanth Reddy @ 2014-08-20 12:46 ` Alex Williamson 2014-08-20 13:44 ` Sreekanth Reddy 0 siblings, 1 reply; 6+ messages in thread From: Alex Williamson @ 2014-08-20 12:46 UTC (permalink / raw) To: Sreekanth Reddy Cc: linux-scsi, linux-kernel, linux-pci, konrad.wilk, Martin K. Petersen, Christoph Hellwig, boris.ostrovsky, Sathya Prakash, Nagalakshmi Nandigama On Wed, 2014-08-20 at 16:39 +0530, Sreekanth Reddy wrote: > HI, > > For SRIOV support, currently in the KVM environment, mpt3sas driver > can use the API pci_vfs_assigned() to know the number of VFs that are > currently assigned to the running VMs. So that during the PF driver > unload time, if the return value of this API is greater than zero the > our driver won't call the pci_disable_sriov() to disable the VFs. > > Now for the same purpose in XEN environment, is there any API similar > to pci_vfs_assigned() which the low lever device driver can use to > know 'the number of VFs that are currently assigned to the running > VMs'. In XEN environment this API pci_vfs_assigned() will return > always zero even though VFs are assigned to the running VMs. Note that pci_vfs_assigned() assigned is only used by legacy KVM device assignment and primarily as a workaround for not using an actual host-based device driver to manage device ownership. When using VFIO-based device assignment with KVM, pci_vfs_assigned() is not updated. Please don't rely on this interface. Thanks, Alex ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How to get the number of VFs assigned to the guests in XEN 2014-08-20 12:46 ` Alex Williamson @ 2014-08-20 13:44 ` Sreekanth Reddy 2014-08-20 14:09 ` Alex Williamson 0 siblings, 1 reply; 6+ messages in thread From: Sreekanth Reddy @ 2014-08-20 13:44 UTC (permalink / raw) To: Alex Williamson Cc: linux-scsi, linux-kernel, linux-pci, konrad.wilk, Martin K. Petersen, Christoph Hellwig, boris.ostrovsky, Sathya Prakash, Nagalakshmi Nandigama Thanks Alex, Then, Is there any other ways to stop accidental unload of PF driver while still some VFs are accessing by the running VMs. Regards, Sreekanth On Wed, Aug 20, 2014 at 6:16 PM, Alex Williamson <alex.williamson@redhat.com> wrote: > On Wed, 2014-08-20 at 16:39 +0530, Sreekanth Reddy wrote: >> HI, >> >> For SRIOV support, currently in the KVM environment, mpt3sas driver >> can use the API pci_vfs_assigned() to know the number of VFs that are >> currently assigned to the running VMs. So that during the PF driver >> unload time, if the return value of this API is greater than zero the >> our driver won't call the pci_disable_sriov() to disable the VFs. >> >> Now for the same purpose in XEN environment, is there any API similar >> to pci_vfs_assigned() which the low lever device driver can use to >> know 'the number of VFs that are currently assigned to the running >> VMs'. In XEN environment this API pci_vfs_assigned() will return >> always zero even though VFs are assigned to the running VMs. > > Note that pci_vfs_assigned() assigned is only used by legacy KVM device > assignment and primarily as a workaround for not using an actual > host-based device driver to manage device ownership. When using > VFIO-based device assignment with KVM, pci_vfs_assigned() is not > updated. Please don't rely on this interface. Thanks, > > Alex > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How to get the number of VFs assigned to the guests in XEN 2014-08-20 13:44 ` Sreekanth Reddy @ 2014-08-20 14:09 ` Alex Williamson 0 siblings, 0 replies; 6+ messages in thread From: Alex Williamson @ 2014-08-20 14:09 UTC (permalink / raw) To: Sreekanth Reddy Cc: linux-scsi, linux-kernel, linux-pci, konrad.wilk, Martin K. Petersen, Christoph Hellwig, boris.ostrovsky, Sathya Prakash, Nagalakshmi Nandigama On Wed, 2014-08-20 at 19:14 +0530, Sreekanth Reddy wrote: > Thanks Alex, > > Then, Is there any other ways to stop accidental unload of PF driver > while still some VFs are accessing by the running VMs. I believe the reason pci_vfs_assigned() and the pci_dev flag that backs it exists is because legacy KVM device assignment does not require a host driver for the device. At best, the assigned device is bound to pci-stub, which is more than happy to release a device at any point in time. This flag was therefore added to indicate that the device was in use, please don't make it disappear. With VFIO, the device is bound to vfio-pci in the host which will only release the device when it is unused, just like any other device driver. If the device is in use, either assigned to a VM or otherwise in use by a userspace driver, vfio-pci will block until unused. There are opportunities that we have yet to implement that we could notify the user of the removal request, triggering a hot-unplug in a guest. Assuming some sort of revoke() functionality gets pushed upstream we could also make an unplug request, wait from some time, then revoke the device from the user. The point however is that device assignment shouldn't be handled as a special case. When pci_disable_sriov() is called, the release functions for any drivers owning an affected VF should be called where we have the opportunity to block until unused. Thanks, Alex > On Wed, Aug 20, 2014 at 6:16 PM, Alex Williamson > <alex.williamson@redhat.com> wrote: > > On Wed, 2014-08-20 at 16:39 +0530, Sreekanth Reddy wrote: > >> HI, > >> > >> For SRIOV support, currently in the KVM environment, mpt3sas driver > >> can use the API pci_vfs_assigned() to know the number of VFs that are > >> currently assigned to the running VMs. So that during the PF driver > >> unload time, if the return value of this API is greater than zero the > >> our driver won't call the pci_disable_sriov() to disable the VFs. > >> > >> Now for the same purpose in XEN environment, is there any API similar > >> to pci_vfs_assigned() which the low lever device driver can use to > >> know 'the number of VFs that are currently assigned to the running > >> VMs'. In XEN environment this API pci_vfs_assigned() will return > >> always zero even though VFs are assigned to the running VMs. > > > > Note that pci_vfs_assigned() assigned is only used by legacy KVM device > > assignment and primarily as a workaround for not using an actual > > host-based device driver to manage device ownership. When using > > VFIO-based device assignment with KVM, pci_vfs_assigned() is not > > updated. Please don't rely on this interface. Thanks, > > > > Alex > > ^ permalink raw reply [flat|nested] 6+ messages in thread
[parent not found: <CAK=zhgpH2tG-EG4QP1SE46e+uHXA+GJGOPA1vi8UqAfRZ-EFTA@mail.gmail.com>]
* Re: How to get the number of VFs assigned to the guests in XEN [not found] <CAK=zhgpH2tG-EG4QP1SE46e+uHXA+GJGOPA1vi8UqAfRZ-EFTA@mail.gmail.com> @ 2014-08-20 22:29 ` Konrad Rzeszutek Wilk 2014-08-21 8:20 ` Sreekanth Reddy 0 siblings, 1 reply; 6+ messages in thread From: Konrad Rzeszutek Wilk @ 2014-08-20 22:29 UTC (permalink / raw) To: Sreekanth Reddy Cc: linux-scsi, linux-kernel, linux-pci, Martin K. Petersen, Christoph Hellwig, Sathya Prakash, Nagalakshmi Nandigama, boris.ostrovsky On Wed, Aug 20, 2014 at 04:33:29PM +0530, Sreekanth Reddy wrote: > HI, > > > > For SRIOV support, currently in the KVM environment, mpt3sas driver can use > the API pci_vfs_assigned() to know the number of VFs that are currently > assigned to the running VMs. So that during the PF driver unload time, if > the return value of this API is greater than zero the our driver won't call > the pci_disable_sriov() to disable the VFs. > > > > Now for the same purpose in XEN environment, is there any API similar to > pci_vfs_assigned() which the low lever device driver can use to know 'the > number of VFs that are currently assigned to the running VMs'. In XEN > environment this API pci_vfs_assigned() will return always zero even though > VFs are assigned to the running VMs. Odd. It should return the same value. Are the devices binded to pci-back? > > > > Regards, > > Sreekanth ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How to get the number of VFs assigned to the guests in XEN 2014-08-20 22:29 ` Konrad Rzeszutek Wilk @ 2014-08-21 8:20 ` Sreekanth Reddy 0 siblings, 0 replies; 6+ messages in thread From: Sreekanth Reddy @ 2014-08-21 8:20 UTC (permalink / raw) To: Konrad Rzeszutek Wilk Cc: linux-scsi, linux-kernel, linux-pci, Martin K. Petersen, Christoph Hellwig, Sathya Prakash, Nagalakshmi Nandigama, boris.ostrovsky Yes, devices are binded to pci-back. On Thu, Aug 21, 2014 at 3:59 AM, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote: > On Wed, Aug 20, 2014 at 04:33:29PM +0530, Sreekanth Reddy wrote: >> HI, >> >> >> >> For SRIOV support, currently in the KVM environment, mpt3sas driver can use >> the API pci_vfs_assigned() to know the number of VFs that are currently >> assigned to the running VMs. So that during the PF driver unload time, if >> the return value of this API is greater than zero the our driver won't call >> the pci_disable_sriov() to disable the VFs. >> >> >> >> Now for the same purpose in XEN environment, is there any API similar to >> pci_vfs_assigned() which the low lever device driver can use to know 'the >> number of VFs that are currently assigned to the running VMs'. In XEN >> environment this API pci_vfs_assigned() will return always zero even though >> VFs are assigned to the running VMs. > > Odd. It should return the same value. Are the devices binded to pci-back? > >> >> >> >> Regards, >> >> Sreekanth ^ permalink raw reply [flat|nested] 6+ messages in thread
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2014-08-20 11:09 How to get the number of VFs assigned to the guests in XEN Sreekanth Reddy
2014-08-20 12:46 ` Alex Williamson
2014-08-20 13:44 ` Sreekanth Reddy
2014-08-20 14:09 ` Alex Williamson
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2014-08-20 22:29 ` Konrad Rzeszutek Wilk
2014-08-21 8:20 ` Sreekanth Reddy
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