From mboxrd@z Thu Jan 1 00:00:00 1970 From: Halil Pasic Subject: Re: [PATCH v3 4/8] s390/airq: use DMA memory for adapter interrupts Date: Tue, 4 Jun 2019 17:06:18 +0200 Message-ID: <20190604170618.74f2c561.pasic@linux.ibm.com> References: <20190529122657.166148-1-mimu@linux.ibm.com> <20190529122657.166148-5-mimu@linux.ibm.com> <20190603172740.1023e078.cohuck@redhat.com> <20190604152256.158d688c.pasic@linux.ibm.com> <20190604165120.5afdce78.cohuck@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190604165120.5afdce78.cohuck@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Cornelia Huck Cc: Vasily Gorbik , Linux-S390 Mailing List , Thomas Huth , Claudio Imbrenda , KVM Mailing List , Sebastian Ott , "Michael S . Tsirkin" , Farhan Ali , Heiko Carstens , Eric Farman , virtualization@lists.linux-foundation.org, Christoph Hellwig , Christian Borntraeger , Michael Mueller , Viktor Mihajlovski , Janosch Frank List-Id: virtualization@lists.linuxfoundation.org On Tue, 4 Jun 2019 16:51:20 +0200 Cornelia Huck wrote: > On Tue, 4 Jun 2019 15:22:56 +0200 > Halil Pasic wrote: > > > On Mon, 3 Jun 2019 17:27:40 +0200 > > Cornelia Huck wrote: > > > > Apologies if that already has been answered (and I missed it in my mail > > > pile...), but two things had come to my mind previously: > > > > > > - CHSC... does anything need to be done there? Last time I asked: > > > "Anyway, css_bus_init() uses some chscs > > > early (before cio_dma_pool_init), so we could not use the pools > > > there, even if we wanted to. Do chsc commands either work, or else > > > fail benignly on a protected virt guest?" > > > > Protected virt won't support all CHSC. The supported ones won't requre > > use of shared memory. So we are fine. > > I suppose the supported ones are the sync chscs that use the chsc area > as a direct parameter (and therefore are handled similarly to the other > I/O instructions that supply a direct parameter)? I don't think we care > about async chscs in KVM/QEMU anyway, as we don't even emulate chsc > subchannels :) (And IIRC, you don't get chsc subchannels in z/VM > guests, either.) Nod. > > > > > > - PCI indicators... does this interact with any dma configuration on > > > the pci device? (I know pci is not supported yet, and I don't really > > > expect any problems.) > > > > > > > It does but, I'm pretty confident we don't have a problem with PCI. IMHO > > Sebastian is the guy who needs to be paranoid about this, and he r-b-ed > > the respective patches. > > Just wanted to make sure that this was on the radar. You guys are > obviously in a better position than me to judge this :) > > Anyway, I do not intend to annoy with those questions, it's just hard > to get a feel if there are areas that still need care if you don't have > access to the documentation for this... if you tell me that you are > aware of it and it should work, that's fine for me. > The questions are important. It is just the not so unusual problem with the availability of public documentation that makes things a bit difficult for me as well. And sorry if these questions were ignored in the past. I did not have the bandwidth to take care of all the questions properly, but I did enough so that the other guys never knew if they need to engage or not. Regards, Halil