From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:50420 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727586AbfFDOwA (ORCPT ); Tue, 4 Jun 2019 10:52:00 -0400 Date: Tue, 4 Jun 2019 16:51:20 +0200 From: Cornelia Huck Subject: Re: [PATCH v3 4/8] s390/airq: use DMA memory for adapter interrupts Message-ID: <20190604165120.5afdce78.cohuck@redhat.com> In-Reply-To: <20190604152256.158d688c.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> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Halil Pasic Cc: Michael Mueller , KVM Mailing List , Linux-S390 Mailing List , Sebastian Ott , Heiko Carstens , virtualization@lists.linux-foundation.org, "Michael S . Tsirkin" , Christoph Hellwig , Thomas Huth , Christian Borntraeger , Viktor Mihajlovski , Vasily Gorbik , Janosch Frank , Claudio Imbrenda , Farhan Ali , Eric Farman , Pierre Morel 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.) > > > - 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. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v3 4/8] s390/airq: use DMA memory for adapter interrupts Date: Tue, 4 Jun 2019 16:51:20 +0200 Message-ID: <20190604165120.5afdce78.cohuck@redhat.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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190604152256.158d688c.pasic@linux.ibm.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: Halil Pasic Cc: Vasily Gorbik , Linux-S390 Mailing List , Thomas Huth , Claudio Imbrenda , KVM Mailing List , Sebastian Ott , "Michael S . Tsirkin" , Pierre Morel , 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 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.) > > > - 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.