From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
kernel-team@cloudflare.com, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v2] virtio_pci: Switch away from deprecated irq_set_affinity_hint
Date: Thu, 26 Oct 2023 13:20:34 -0400 [thread overview]
Message-ID: <20231026131830-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <87wmv91h3p.fsf@cloudflare.com>
On Thu, Oct 26, 2023 at 06:25:08PM +0200, Jakub Sitnicki wrote:
> On Wed, Oct 25, 2023 at 04:53 PM +02, Jakub Sitnicki wrote:
> > Since commit 65c7cdedeb30 ("genirq: Provide new interfaces for affinity
> > hints") irq_set_affinity_hint is being phased out.
> >
> > Switch to new interfaces for setting and applying irq affinity hints.
> >
> > Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
> > ---
> > v2:
> > - Leave cpumask_copy as is. We can't pass pointer to stack memory as hint.
> > Proposed a change to IRQ affinity interface to address this limitation:
> > https://lore.kernel.org/r/20231025141517.375378-1-jakub@cloudflare.com
>
> Just a note to the ^ - if we wanted to get rid of msix_affinity_masks,
> we could call irq_set_affinity directly, instead of calling it through
> irq_set_affinity[_and]_hint.
>
> The hint wouldn't be available any more in /proc/irq/N/affinity_hint,
> but the same information can be gathered from /proc/irq/N/smp_affinity.
>
> [...]
So we are potentially breaking some userspace - what's the value we
gain? Is there some way we can make disable_irq/enable_irq work?
That would have a lot of value.
There is an actual need for that in virtio for coco but we can't use
these APIs with affinity managed IRQs.
--
MST
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WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jakub Sitnicki <jakub@cloudflare.com>
Cc: virtualization@lists.linux-foundation.org,
Jason Wang <jasowang@redhat.com>,
Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
linux-kernel@vger.kernel.org, kernel-team@cloudflare.com
Subject: Re: [PATCH v2] virtio_pci: Switch away from deprecated irq_set_affinity_hint
Date: Thu, 26 Oct 2023 13:20:34 -0400 [thread overview]
Message-ID: <20231026131830-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <87wmv91h3p.fsf@cloudflare.com>
On Thu, Oct 26, 2023 at 06:25:08PM +0200, Jakub Sitnicki wrote:
> On Wed, Oct 25, 2023 at 04:53 PM +02, Jakub Sitnicki wrote:
> > Since commit 65c7cdedeb30 ("genirq: Provide new interfaces for affinity
> > hints") irq_set_affinity_hint is being phased out.
> >
> > Switch to new interfaces for setting and applying irq affinity hints.
> >
> > Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
> > ---
> > v2:
> > - Leave cpumask_copy as is. We can't pass pointer to stack memory as hint.
> > Proposed a change to IRQ affinity interface to address this limitation:
> > https://lore.kernel.org/r/20231025141517.375378-1-jakub@cloudflare.com
>
> Just a note to the ^ - if we wanted to get rid of msix_affinity_masks,
> we could call irq_set_affinity directly, instead of calling it through
> irq_set_affinity[_and]_hint.
>
> The hint wouldn't be available any more in /proc/irq/N/affinity_hint,
> but the same information can be gathered from /proc/irq/N/smp_affinity.
>
> [...]
So we are potentially breaking some userspace - what's the value we
gain? Is there some way we can make disable_irq/enable_irq work?
That would have a lot of value.
There is an actual need for that in virtio for coco but we can't use
these APIs with affinity managed IRQs.
--
MST
next prev parent reply other threads:[~2023-10-26 17:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-25 14:53 [PATCH v2] virtio_pci: Switch away from deprecated irq_set_affinity_hint Jakub Sitnicki via Virtualization
2023-10-25 14:53 ` Jakub Sitnicki
2023-10-26 3:36 ` Xuan Zhuo
2023-10-26 3:36 ` Xuan Zhuo
2023-10-26 16:25 ` Jakub Sitnicki via Virtualization
2023-10-26 16:25 ` Jakub Sitnicki
2023-10-26 17:20 ` Michael S. Tsirkin [this message]
2023-10-26 17:20 ` Michael S. Tsirkin
2023-10-27 10:03 ` Jakub Sitnicki via Virtualization
2023-10-27 10:03 ` Jakub Sitnicki
2023-10-28 1:45 ` Xuan Zhuo
2023-10-28 1:45 ` Xuan Zhuo
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