From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Akihiko Odaki <akihiko.odaki@daynix.com>
Cc: virtio-comment@lists.oasis-open.org, eric.auger@redhat.com,
virtio-dev@lists.oasis-open.org,
Zide Chen <zide.chen@intel.corp-partner.google.com>,
crosvm-dev@chromium.org
Subject: [virtio-comment] Re: [PATCH 4/4] virtio-iommu: Clarify hot-unplug behavior
Date: Mon, 14 Aug 2023 12:25:02 +0100 [thread overview]
Message-ID: <20230814112502.GA37241@myrica> (raw)
In-Reply-To: <b7b62822-4371-4a47-bc28-25a0b0ef92c5@daynix.com>
On Sat, Aug 12, 2023 at 03:25:10PM +0900, Akihiko Odaki wrote:
> > > By the way, crosvm's logic to detach endpoint on removal looks incorrect for
> > > me. A domain may have several endpoints attached, but the code looks like
> > > it's always destroying a domain whether there are other endpoints attached
> > > to the domain. I'm adding Zide Chen, who wrote the code according to git
> > > blame, and crosvm-dev@chromium.org to CC.
> >
> > Link to this thread for more context:
> > https://lore.kernel.org/virtio-dev/20230803153238.541803-5-jean-philippe@linaro.org/
> >
> > I thought crosvm rejected attaching multiple endpoints to one domain but I
> > think I misread. Rejecting multiple attach would be a straightforward fix
> > (it's allowed by the spec), though it would prevent assigning endpoints
> > that cannot be isolated from each others by the hardware (the driver won't
> > attach those to different domains, if it's made aware that they should be
> > in the same IOMMU group, for example if they are on a conventional PCI
> > bus).
>
> Now we figured out an endpoint should not be detached from a domain without
> a request from the driver anyway so the code to detach an endpoint can be
> simply removed.
Yes, but I think the other detach path, when handling ATTACH or DETACH
requests, doesn't support domains with multiple endpoints attached either:
// Currently, we only support detaching an endpoint if it is the only endpoint attached
// to its domain.
But the ATTACH handler seems to accept attaching multiple endpoints to the
same domain?
Thanks,
Jean
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prev parent reply other threads:[~2023-08-14 11:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230803153238.541803-1-jean-philippe@linaro.org>
[not found] ` <20230803153238.541803-5-jean-philippe@linaro.org>
[not found] ` <ca33f633-26ea-b254-a75d-3bbf86d15d24@daynix.com>
2023-08-10 15:10 ` [virtio-comment] Re: [PATCH 4/4] virtio-iommu: Clarify hot-unplug behavior Jean-Philippe Brucker
[not found] ` <96d8b628-3f21-40de-ab2e-20e6043dc937@daynix.com>
2023-08-11 14:20 ` Jean-Philippe Brucker
[not found] ` <b7b62822-4371-4a47-bc28-25a0b0ef92c5@daynix.com>
2023-08-14 11:25 ` Jean-Philippe Brucker [this message]
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