From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH 0/3] PCI: Rework config space locking, add INTx masking services Date: Fri, 14 Oct 2011 16:48:50 +0200 Message-ID: <4E984BD2.6090907@siemens.com> References: <20111006084853.033d8d0f@jbarnes-desktop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Hans J. Koch" , Greg Kroah-Hartman , "Michael S. Tsirkin" , "kvm@vger.kernel.org" , Brian King To: Jesse Barnes Return-path: In-Reply-To: <20111006084853.033d8d0f@jbarnes-desktop> Sender: linux-pci-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 2011-10-06 17:48, Jesse Barnes wrote: > On Mon, 12 Sep 2011 18:54:01 +0200 > Jan Kiszka wrote: > >> This series tries to heal the currently broken locking scheme around PCI >> config space accesses. >> >> We have an interface lock out access via sysfs, but that service wrongly >> assumes it is only called by one instance at a time for some device. So >> two loops doing >> >> echo 1 > /sys/bus/pci/devices//reset >> >> in parallel will trigger a kernel BUG at the moment. >> >> Besides synchronizing with user space, we also need to manage config >> space access of generic PCI drivers. They need to mask legacy interrupt >> lines while the specific driver runs in user space or a guest OS. >> >> The approach taken here is provide mutex-like locking for general >> access - which still requires a special mechanism due to requirements of >> the IBM Power RAID SCSI driver. Furthermore, INTx masking is now >> available via the PCI core and synchronized via the internal pci_lock. >> >> Not sure who may want to take this, so I'm CC'ing broadly. > > ISTR a bunch of discussion about this (just back from lots of work > travel and vacation, sorry I missed most of it). > > Is this the agreed upon way of handling it? If so, can I get some > Reviewed/Acked-bys from people? I hope this is acceptable. These changes are required for further improvements of the KVM device assignment support (INTx sharing). So I would appreciate any ack or whatever feedback as well. Thanks, Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux