Re: [PATCH v3 4/8] s390/airq: use DMA memory for adapter interrupts
From: Halil Pasic <pasic@linux.ibm.com>
Date: 2019-06-04 15:07:27
Also in:
kvm, linux-s390
On Tue, 4 Jun 2019 16:51:20 +0200 Cornelia Huck [off-list ref] wrote:
On Tue, 4 Jun 2019 15:22:56 +0200 Halil Pasic [off-list ref] wrote:quoted
On Mon, 3 Jun 2019 17:27:40 +0200 Cornelia Huck [off-list ref] wrote:quoted
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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.
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- 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