From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:45745 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754386AbaHTMqT (ORCPT ); Wed, 20 Aug 2014 08:46:19 -0400 Message-ID: <1408538771.11383.33.camel@ul30vt.home> Subject: Re: How to get the number of VFs assigned to the guests in XEN From: Alex Williamson To: Sreekanth Reddy Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, konrad.wilk@oracle.com, "Martin K. Petersen" , Christoph Hellwig , boris.ostrovsky@oracle.com, Sathya Prakash , Nagalakshmi Nandigama Date: Wed, 20 Aug 2014 06:46:11 -0600 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org List-ID: 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