From: Thomas Gleixner <tglx@linutronix.de>
To: David Woodhouse <dwmw2@infradead.org>, x86@kernel.org
Cc: iommu <iommu@lists.linux-foundation.org>,
kvm <kvm@vger.kernel.org>,
linux-hyperv@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 10/13] x86/irq: Limit IOAPIC and MSI domains' affinity without IR
Date: Wed, 07 Oct 2020 19:23:25 +0200 [thread overview]
Message-ID: <874kn63q7m.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <2f09a1f97d97e638e90c6eca3ebeebb4be852f58.camel@infradead.org>
On Wed, Oct 07 2020 at 16:46, David Woodhouse wrote:
> The PCI MSI domain, HPET, and even the IOAPIC are just the things out
> there on the bus which might perform those physical address cycles. And
> yes, as you say they're just a message store sending exactly the
> message that was composed for them. They know absolutely nothing about
> what the message means and how it is composed.
That's what I said.
> It so happens that in Linux, we don't really architect the software
> like that. So each of the PCI MSI domain, HPET, and IOAPIC have their
> *own* message composer which has the same limits and composes basically
> the same messages as if it was *their* format, not dictated to them by
> the APIC upstream. And that's what we're both getting our panties in a
> knot about, I think.
Are you actually reading what I write and caring to look at the code?
PCI-MSI does not have a compose message callback in the irq chip. The
message is composed by the underlying parent domain. Same for HPET.
The only dogdy part is the IO/APIC for hysterical raisins and because
I did not come around yet to sort that out.
> It really doesn't matter that much to the underlying generic irqdomain
> support for limited affinities. Except that you want to make the
> generic code support the concept of a child domain supporting *more*
> CPUs than its parent, which really doesn't make much sense if you think
> about it.
Right. So we really want to stick the restriction into a compat-MSI
domain to make stuff match reality and to avoid banging the head against
the wall sooner than later.
Thanks,
tglx
next prev parent reply other threads:[~2020-10-07 17:23 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-05 15:28 [PATCH 0/13] Fix per-domain IRQ affinity, allow >255 CPUs on x86 without IRQ remapping David Woodhouse
2020-10-05 15:28 ` [PATCH 01/13] x86/apic: Use x2apic in guest kernels even with unusable CPUs David Woodhouse
2020-10-05 15:28 ` [PATCH 02/13] x86/msi: Only use high bits of MSI address for DMAR unit David Woodhouse
2020-10-06 20:45 ` Thomas Gleixner
2020-10-05 15:28 ` [PATCH 03/13] x86/ioapic: Handle Extended Destination ID field in RTE David Woodhouse
2020-10-05 15:28 ` [PATCH 04/13] x86/apic: Support 15 bits of APIC ID in IOAPIC/MSI where available David Woodhouse
2020-10-05 15:28 ` [PATCH 05/13] genirq: Prepare for default affinity to be passed to __irq_alloc_descs() David Woodhouse
2020-10-06 21:01 ` Thomas Gleixner
2020-10-06 21:07 ` David Woodhouse
2020-10-05 15:28 ` [PATCH 06/13] genirq: Add default_affinity argument " David Woodhouse
2020-10-06 21:06 ` Thomas Gleixner
2020-10-05 15:28 ` [PATCH 07/13] irqdomain: Add max_affinity argument to irq_domain_alloc_descs() David Woodhouse
2020-10-06 21:26 ` Thomas Gleixner
2020-10-07 7:19 ` David Woodhouse
2020-10-07 13:37 ` Thomas Gleixner
2020-10-07 14:10 ` David Woodhouse
2020-10-07 15:57 ` Thomas Gleixner
2020-10-07 16:11 ` David Woodhouse
2020-10-07 20:53 ` Thomas Gleixner
2020-10-08 7:21 ` David Woodhouse
2020-10-08 9:34 ` Thomas Gleixner
2020-10-08 11:10 ` David Woodhouse
2020-10-08 12:40 ` Thomas Gleixner
2020-10-09 7:54 ` David Woodhouse
2020-10-05 15:28 ` [PATCH 08/13] genirq: Add irq_domain_set_affinity() David Woodhouse
2020-10-06 21:32 ` Thomas Gleixner
2020-10-07 7:22 ` David Woodhouse
2020-10-05 15:28 ` [PATCH 09/13] x86/irq: Add x86_non_ir_cpumask David Woodhouse
2020-10-06 21:42 ` Thomas Gleixner
2020-10-07 7:25 ` David Woodhouse
2020-10-05 15:28 ` [PATCH 10/13] x86/irq: Limit IOAPIC and MSI domains' affinity without IR David Woodhouse
2020-10-06 21:54 ` Thomas Gleixner
2020-10-07 7:48 ` David Woodhouse
2020-10-07 12:59 ` Thomas Gleixner
2020-10-07 13:08 ` David Woodhouse
2020-10-07 14:05 ` Thomas Gleixner
2020-10-07 14:23 ` David Woodhouse
2020-10-07 16:02 ` Thomas Gleixner
2020-10-07 16:15 ` David Woodhouse
2020-10-07 15:05 ` David Woodhouse
2020-10-07 15:25 ` Thomas Gleixner
2020-10-07 15:46 ` David Woodhouse
2020-10-07 17:23 ` Thomas Gleixner [this message]
2020-10-07 17:34 ` David Woodhouse
2020-10-05 15:28 ` [PATCH 11/13] x86/smp: Allow more than 255 CPUs even without interrupt remapping David Woodhouse
2020-10-05 15:28 ` [PATCH 12/13] iommu/irq_remapping: Kill most of hyperv-iommu.c now it's redundant David Woodhouse
2020-10-05 15:28 ` [PATCH 13/13] x86/kvm: Add KVM_FEATURE_MSI_EXT_DEST_ID David Woodhouse
2020-10-07 8:14 ` Paolo Bonzini
2020-10-07 8:59 ` David Woodhouse
2020-10-07 11:15 ` Paolo Bonzini
2020-10-07 12:04 ` David Woodhouse
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=874kn63q7m.fsf@nanos.tec.linutronix.de \
--to=tglx@linutronix.de \
--cc=dwmw2@infradead.org \
--cc=iommu@lists.linux-foundation.org \
--cc=kvm@vger.kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).