From: Marc Zyngier <maz@kernel.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>
Subject: Re: [RFC 0/2] irqchip/gic-v3-its: Introduce virtual ITS
Date: Tue, 22 Jun 2021 18:32:47 +0100 [thread overview]
Message-ID: <87sg19by9s.wl-maz@kernel.org> (raw)
In-Reply-To: <20210622155313.3819952-1-boqun.feng@gmail.com>
On Tue, 22 Jun 2021 16:53:11 +0100,
Boqun Feng <boqun.feng@gmail.com> wrote:
>
> Hi Marc,
>
> Here is an RFC for supporting platforms having LPI supported but without
> ITS. And this is for the virtual PCI support for ARM64 Hyper-V guests.
> We currently choose this approach (LPI w/o ITS) because a) it's allowed
> for GICv3 and b) ITS may not be a more efficient way to configure LPIs
> compared to hypercalls, but we'd like to get feedbacks from the
> community.
>
> Besides, patch #1 fixes a bug which I found while I was at it.
>
> Looking forwards to any comment and suggestion!
My suggestion is to not do that. The ITS driver is used to drive an
ITS. That, and only that. The simple fact that you mention hypercalls
shows that this is *not* what the architecture allows.
So if you are going to implement something that is evidently outside
of the scope of the architecture, keep it in some Hyper-V specific
code that doesn't involve the ITS driver.
All you need is something that will piggy-back on top of the GIC
driver using a hierarchical driver. We support that today. Of course,
you'll have to invent your own firmware interface for discovery.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
prev parent reply other threads:[~2021-06-22 17:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-22 15:53 [RFC 0/2] irqchip/gic-v3-its: Introduce virtual ITS Boqun Feng
2021-06-22 15:53 ` [RFC 1/2] irqchip/gic-v3-its: Free collections if its domain initialization fails Boqun Feng
2021-06-22 15:53 ` [RFC 2/2] irqchip/gic-v3-its: Introduce virtual ITS Boqun Feng
2021-06-22 17:17 ` Marc Zyngier
2021-06-22 17:32 ` Marc Zyngier [this message]
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=87sg19by9s.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=arnd@arndb.de \
--cc=bhelgaas@google.com \
--cc=boqun.feng@gmail.com \
--cc=catalin.marinas@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=will@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).