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Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created i
From: |
Peter Xu |
Subject: |
Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance |
Date: |
Wed, 8 Mar 2017 17:16:08 +0800 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Wed, Mar 08, 2017 at 05:09:45PM +0800, Peter Xu wrote:
> On Wed, Mar 08, 2017 at 10:17:09AM +0200, Marcel Apfelbaum wrote:
>
> [...]
>
> >
> > I am sorry I was not clear enough:
> > If a device is added after the system is up (hotplug), we cannot depend on
> > the "machine_done"
> > event to enable "bus master".
> > This is why we have
> > if (qdev_hotplug)
> > pci_init_bus_master(pci_dev);
> >
> > The code you proposed changes the order, so this call is done *after*
> > realize.
> >
> > My question was: What if any other device may require the bus_master_as
> > at realize time (and can be hot-plugged) ?
> > For example: hcd-ehci/hcd-ohci devices call pci_get_address_space()
> > and caches the bus_master_as.
>
> Oh, I didn't notice that there are other devices that used
> bus_master_as during realization. If so... Would this really work even
> without hot plug? Considering that bus_master_as won't be inited until
> machine done phase?
Please ignore my question... I think the answer is that these devices
are only caching the pointer of bus_master_as. So it won't really use
the address space before machine_done.
If so, IMHO moving pci_init_bus_master() after device specific
realize() is okay as well then, right?
Thanks,
-- peterx
Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance, Igor Mammedov, 2017/03/08
- Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance, Jason Wang, 2017/03/08
- Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance, Igor Mammedov, 2017/03/09
- Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance, Paolo Bonzini, 2017/03/09
- Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance, Jason Wang, 2017/03/09
- Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance, Paolo Bonzini, 2017/03/09
- Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance, Michael S. Tsirkin, 2017/03/09