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From: Pierre Morel <pmorel@linux.ibm.com>
To: Halil Pasic <pasic@linux.ibm.com>, Cornelia Huck <cohuck@redhat.com>
Cc: Thomas Huth <thuth@redhat.com>,
	Boris Fiuczynski <fiuczy@linux.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Richard Henderson <rth@twiddle.net>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel@nongnu.org,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	qemu-s390x@nongnu.org,
	Viktor Mihajlovski <mihajlov@linux.ibm.com>,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH v2 1/1] virtio-ccw: auto-manage VIRTIO_F_IOMMU_PLATFORM if PV
Date: Tue, 9 Jun 2020 16:02:45 +0200	[thread overview]
Message-ID: <1d914b70-e30c-ea1f-3356-2fc53b63ce58@linux.ibm.com> (raw)
In-Reply-To: <20200609114130.0ca9190b.pasic@linux.ibm.com>



On 2020-06-09 11:41, Halil Pasic wrote:
> On Tue, 9 Jun 2020 08:44:02 +0200
> Cornelia Huck <cohuck@redhat.com> wrote:
> 
>> On Mon, 8 Jun 2020 19:00:45 +0200
>> Halil Pasic <pasic@linux.ibm.com> wrote:
>>
>>

...snip...

>>
>> I mean, can a virtio devices without IOMMU_PLATFORM act as a transition
>> blocker (i.e. an attempt by a guest to move to pv would fail?)
>>
> 
> I don't know. Janosch could answer that, but he is on vacation. Adding
> Claudio maybe he can answer. My understanding is, that while it might be
> possible, it is ugly at best. The ability to do a transition is
> indicated by a CPU model feature. Indicating the feature to the guest and
> then failing the transition sounds wrong to me.


The guest image is encrypted and the transition to PV is done by the 
stage 3 boot loader, part of the loaded image, before Linux is started.
At this moment the guest is not aware of the virtio devices.

Regards,
Pierre

-- 
Pierre Morel
IBM Lab Boeblingen


  reply	other threads:[~2020-06-09 14:05 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14 22:11 [PATCH v2 1/1] virtio-ccw: auto-manage VIRTIO_F_IOMMU_PLATFORM if PV Halil Pasic
2020-05-20 12:16 ` Halil Pasic
2020-05-20 16:23 ` Michael S. Tsirkin
2020-05-22 21:04   ` Halil Pasic
2020-05-28 11:21     ` Cornelia Huck
2020-05-28 14:42       ` Janosch Frank
2020-05-28 18:49         ` Halil Pasic
2020-05-28 17:52       ` Halil Pasic
2020-06-05 23:32   ` Halil Pasic
2020-06-08 16:14     ` Cornelia Huck
2020-06-08 17:00       ` Halil Pasic
2020-06-09  6:44         ` Cornelia Huck
2020-06-09  9:41           ` Halil Pasic
2020-06-09 14:02             ` Pierre Morel [this message]
2020-06-09 15:47             ` Claudio Imbrenda
2020-06-09 16:05               ` Cornelia Huck
2020-06-09 16:41                 ` Halil Pasic
2020-06-10 13:34                 ` Halil Pasic
2020-06-09 16:28               ` Halil Pasic
2020-06-09 16:44                 ` Michael S. Tsirkin
2020-06-10  4:31                   ` David Gibson
2020-06-10  7:22                     ` David Hildenbrand
2020-06-10 10:07                       ` David Gibson
2020-06-10 10:24                         ` David Hildenbrand
2020-06-10 13:00                           ` Halil Pasic
2020-06-10 13:19                           ` Viktor Mihajlovski
2020-06-10 14:00                             ` David Hildenbrand
2020-06-19  0:36                             ` David Gibson
2020-06-19  0:33                           ` David Gibson
2020-06-10 13:15                   ` Halil Pasic
2020-06-10  4:29                 ` David Gibson
2020-06-10 13:57                   ` Halil Pasic
2020-06-19  0:59                     ` David Gibson
2020-06-09 16:41               ` Michael S. Tsirkin
2020-06-10  4:25           ` David Gibson
2020-06-10 21:37             ` Halil Pasic
2020-06-19  1:01               ` David Gibson
2020-06-08 16:53     ` Michael S. Tsirkin

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