From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Cc: mark.rutland@arm.com, virtio-dev@lists.oasis-open.org,
lorenzo.pieralisi@arm.com, tnowicki@caviumnetworks.com,
devicetree@vger.kernel.org, marc.zyngier@arm.com,
linux-pci@vger.kernel.org, joro@8bytes.org, will.deacon@arm.com,
virtualization@lists.linux-foundation.org, eric.auger@redhat.com,
iommu@lists.linux-foundation.org, robh+dt@kernel.org,
bhelgaas@google.com, robin.murphy@arm.com,
kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v5 5/7] iommu: Add virtio-iommu driver
Date: Tue, 27 Nov 2018 13:13:24 -0500 [thread overview]
Message-ID: <20181127131116-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <fd221210-7e12-1d15-0c80-52a761f6893d@arm.com>
On Tue, Nov 27, 2018 at 05:50:50PM +0000, Jean-Philippe Brucker wrote:
> > I didn't notice this in the past but it seems this will spin
> > with interrupts disabled until host handles the request.
> > Please do not do this - host execution can be another
> > task that needs the same host CPU. This will then disable
> > interrupts for a very very long time.
>
> In the guest yes, but that doesn't prevent the host from running another
> task right? My tests run fine when QEMU is bound to a single CPU, even
> though vcpu and viommu run in different threads
So a kind of a solution is to add a config space field for sync.
That at least can give host a hint that yes, vcpu
is stopped now and it should do something else.
Not ideal but better than polling VQ forever.
--
MST
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Cc: mark.rutland@arm.com, virtio-dev@lists.oasis-open.org,
lorenzo.pieralisi@arm.com, tnowicki@caviumnetworks.com,
devicetree@vger.kernel.org, marc.zyngier@arm.com,
linux-pci@vger.kernel.org, joro@8bytes.org, will.deacon@arm.com,
virtualization@lists.linux-foundation.org, eric.auger@redhat.com,
iommu@lists.linux-foundation.org, robh+dt@kernel.org,
bhelgaas@google.com, robin.murphy@arm.com,
kvmarm@lists.cs.columbia.edu
Subject: [virtio-dev] Re: [PATCH v5 5/7] iommu: Add virtio-iommu driver
Date: Tue, 27 Nov 2018 13:13:24 -0500 [thread overview]
Message-ID: <20181127131116-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <fd221210-7e12-1d15-0c80-52a761f6893d@arm.com>
On Tue, Nov 27, 2018 at 05:50:50PM +0000, Jean-Philippe Brucker wrote:
> > I didn't notice this in the past but it seems this will spin
> > with interrupts disabled until host handles the request.
> > Please do not do this - host execution can be another
> > task that needs the same host CPU. This will then disable
> > interrupts for a very very long time.
>
> In the guest yes, but that doesn't prevent the host from running another
> task right? My tests run fine when QEMU is bound to a single CPU, even
> though vcpu and viommu run in different threads
So a kind of a solution is to add a config space field for sync.
That at least can give host a hint that yes, vcpu
is stopped now and it should do something else.
Not ideal but better than polling VQ forever.
--
MST
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next prev parent reply other threads:[~2018-11-27 18:13 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-22 19:37 [PATCH v5 0/7] Add virtio-iommu driver Jean-Philippe Brucker
2018-11-22 19:37 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-22 19:37 ` [PATCH v5 1/7] dt-bindings: virtio-mmio: Add IOMMU description Jean-Philippe Brucker
2018-11-22 19:37 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-22 19:37 ` Jean-Philippe Brucker
2018-11-22 19:37 ` [PATCH v5 2/7] dt-bindings: virtio: Add virtio-pci-iommu node Jean-Philippe Brucker
2018-11-22 19:37 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-22 19:37 ` Jean-Philippe Brucker
2018-11-22 19:37 ` [PATCH v5 3/7] of: Allow the iommu-map property to omit untranslated devices Jean-Philippe Brucker
2018-11-22 19:37 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-22 19:37 ` Jean-Philippe Brucker
2018-11-22 19:37 ` [PATCH v5 4/7] PCI: OF: Initialize dev->fwnode appropriately Jean-Philippe Brucker
2018-11-22 19:37 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-22 19:37 ` Jean-Philippe Brucker
2018-11-22 19:37 ` [PATCH v5 5/7] iommu: Add virtio-iommu driver Jean-Philippe Brucker
2018-11-22 19:37 ` Jean-Philippe Brucker
2018-11-22 19:37 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-23 8:27 ` Auger Eric
[not found] ` <20181122193801.50510-6-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-11-23 8:27 ` Auger Eric
2018-11-23 8:27 ` [virtio-dev] " Auger Eric
2018-11-23 8:27 ` Auger Eric
2018-11-23 21:48 ` Michael S. Tsirkin
2018-11-23 21:48 ` [virtio-dev] " Michael S. Tsirkin
2018-11-23 21:48 ` Michael S. Tsirkin
2018-11-27 17:58 ` Jean-Philippe Brucker
2018-11-27 17:58 ` Jean-Philippe Brucker
2018-11-27 17:58 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-27 18:10 ` Michael S. Tsirkin
2018-11-27 18:10 ` Michael S. Tsirkin
2018-11-27 18:10 ` [virtio-dev] " Michael S. Tsirkin
2018-11-23 21:48 ` Michael S. Tsirkin
2018-11-23 21:56 ` Michael S. Tsirkin
2018-11-23 21:56 ` [virtio-dev] " Michael S. Tsirkin
2018-11-27 17:55 ` Jean-Philippe Brucker
2018-11-27 17:55 ` Jean-Philippe Brucker
2018-11-27 17:55 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-27 18:10 ` Michael S. Tsirkin
2018-11-27 18:10 ` [virtio-dev] " Michael S. Tsirkin
2018-12-07 18:52 ` Jean-Philippe Brucker
2018-12-07 18:52 ` [virtio-dev] " Jean-Philippe Brucker
2018-12-07 18:52 ` Jean-Philippe Brucker
[not found] ` <e1dde79c-0bc4-ea99-1bb0-9e70b56955fb-5wv7dgnIgG8@public.gmane.org>
2018-12-12 14:56 ` Michael S. Tsirkin
2018-12-12 14:56 ` Michael S. Tsirkin
2018-12-12 14:56 ` Michael S. Tsirkin
[not found] ` <20181212093709-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2018-12-12 15:27 ` Auger Eric
2018-12-12 15:27 ` Auger Eric
2018-12-12 15:27 ` Auger Eric
2018-12-13 12:37 ` Robin Murphy
2018-12-13 12:37 ` Robin Murphy
2018-12-13 12:37 ` Robin Murphy
2018-12-13 14:13 ` Auger Eric
2018-12-13 14:13 ` Auger Eric
2018-12-13 14:13 ` [virtio-dev] " Auger Eric
2018-12-13 14:13 ` Auger Eric
2018-12-12 15:27 ` Auger Eric
2018-12-12 14:56 ` Michael S. Tsirkin
2018-12-07 18:52 ` Jean-Philippe Brucker
2018-11-27 18:10 ` Michael S. Tsirkin
2018-11-23 21:56 ` Michael S. Tsirkin
2018-11-23 22:02 ` Michael S. Tsirkin
2018-11-23 22:02 ` Michael S. Tsirkin
2018-11-23 22:02 ` [virtio-dev] " Michael S. Tsirkin
2018-11-27 17:50 ` Jean-Philippe Brucker
2018-11-27 17:50 ` Jean-Philippe Brucker
2018-11-27 17:50 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-27 18:04 ` Michael S. Tsirkin
2018-11-27 18:04 ` [virtio-dev] " Michael S. Tsirkin
2018-11-27 18:10 ` Jean-Philippe Brucker
2018-11-27 18:10 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-27 18:53 ` Michael S. Tsirkin
2018-11-27 18:53 ` [virtio-dev] " Michael S. Tsirkin
2018-12-10 15:06 ` Jean-Philippe Brucker
2018-12-10 15:06 ` [virtio-dev] " Jean-Philippe Brucker
2018-12-10 22:53 ` Michael S. Tsirkin
2018-12-10 22:53 ` Michael S. Tsirkin
2018-12-10 22:53 ` [virtio-dev] " Michael S. Tsirkin
[not found] ` <20181210175132-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2018-12-11 16:29 ` Jean-Philippe Brucker
2018-12-11 16:29 ` [virtio-dev] " Jean-Philippe Brucker
2018-12-11 16:29 ` Jean-Philippe Brucker
2018-12-11 16:29 ` Jean-Philippe Brucker
2018-12-10 15:06 ` Jean-Philippe Brucker
2018-11-27 18:53 ` Michael S. Tsirkin
2018-11-27 18:10 ` Jean-Philippe Brucker
2018-11-27 18:13 ` Michael S. Tsirkin
2018-11-27 18:13 ` Michael S. Tsirkin [this message]
2018-11-27 18:13 ` [virtio-dev] " Michael S. Tsirkin
2018-11-22 19:38 ` [PATCH v5 6/7] iommu/virtio: Add probe request Jean-Philippe Brucker
2018-11-22 19:38 ` Jean-Philippe Brucker
2018-11-22 19:38 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-22 19:38 ` [PATCH v5 7/7] iommu/virtio: Add event queue Jean-Philippe Brucker
2018-11-22 19:38 ` [virtio-dev] " Jean-Philippe Brucker
2018-11-22 19:38 ` Jean-Philippe Brucker
2018-11-23 8:28 ` [PATCH v5 0/7] Add virtio-iommu driver Auger Eric
2018-11-23 8:28 ` [virtio-dev] " Auger Eric
2018-11-27 7:09 ` Bharat Bhushan
2018-11-27 7:09 ` Bharat Bhushan
2018-11-27 7:09 ` [virtio-dev] " Bharat Bhushan
2018-11-23 8:28 ` Auger Eric
[not found] ` <20181122193801.50510-1-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-11-27 16:53 ` Michael S. Tsirkin
2018-11-27 16:53 ` [virtio-dev] " Michael S. Tsirkin
2018-11-27 16:53 ` Michael S. Tsirkin
2018-11-27 17:09 ` Auger Eric
2018-11-27 17:09 ` [virtio-dev] " Auger Eric
[not found] ` <6c061729-c404-ac25-f86f-7fe222bf5bc7-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-11-27 17:16 ` Michael S. Tsirkin
2018-11-27 17:16 ` [virtio-dev] " Michael S. Tsirkin
2018-11-27 17:16 ` Michael S. Tsirkin
2018-11-27 18:02 ` Auger Eric
2018-11-27 18:02 ` [virtio-dev] " Auger Eric
2018-11-27 18:02 ` Auger Eric
2018-12-03 13:27 ` Auger Eric
2018-12-03 13:27 ` [virtio-dev] " Auger Eric
2018-12-03 13:27 ` Auger Eric
2018-11-27 17:16 ` Michael S. Tsirkin
2018-11-27 17:09 ` Auger Eric
2018-11-27 16:53 ` Michael S. Tsirkin
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