From: Pierre Morel <pmorel@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: linux-kernel@vger.kernel.org, pasic@linux.ibm.com,
borntraeger@de.ibm.com, frankja@linux.ibm.com, mst@redhat.com,
jasowang@redhat.com, kvm@vger.kernel.org,
linux-s390@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH] s390: protvirt: virtio: Refuse device without IOMMU
Date: Wed, 10 Jun 2020 17:27:01 +0200 [thread overview]
Message-ID: <8b15139d-cd38-0861-1510-9a53530a4637@linux.ibm.com> (raw)
In-Reply-To: <20200610165305.1a34c548.cohuck@redhat.com>
On 2020-06-10 16:53, Cornelia Huck wrote:
> On Wed, 10 Jun 2020 16:37:55 +0200
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> On 2020-06-10 15:24, Cornelia Huck wrote:
>>> On Wed, 10 Jun 2020 15:11:51 +0200
>>> Pierre Morel <pmorel@linux.ibm.com> wrote:
>>>
>>>> Protected Virtualisation protects the memory of the guest and
>>>> do not allow a the host to access all of its memory.
>>>>
>>>> Let's refuse a VIRTIO device which does not use IOMMU
>>>> protected access.
>>>>
>>>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>>>> ---
>>>> drivers/s390/virtio/virtio_ccw.c | 5 +++++
>>>> 1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
>>>> index 5730572b52cd..06ffbc96587a 100644
>>>> --- a/drivers/s390/virtio/virtio_ccw.c
>>>> +++ b/drivers/s390/virtio/virtio_ccw.c
>>>> @@ -986,6 +986,11 @@ static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
>>>> if (!ccw)
>>>> return;
>>>>
>>>> + /* Protected Virtualisation guest needs IOMMU */
>>>> + if (is_prot_virt_guest() &&
>>>> + !__virtio_test_bit(vdev, VIRTIO_F_IOMMU_PLATFORM))
>>>> + status &= ~VIRTIO_CONFIG_S_FEATURES_OK;
>>>> +
>>>
>>> set_status seems like an odd place to look at features; shouldn't that
>>> rather be done in finalize_features?
>>
>> Right, looks better to me too.
>> What about:
>>
>>
>>
>> diff --git a/drivers/s390/virtio/virtio_ccw.c
>> b/drivers/s390/virtio/virtio_ccw.c
>> index 06ffbc96587a..227676297ea0 100644
>> --- a/drivers/s390/virtio/virtio_ccw.c
>> +++ b/drivers/s390/virtio/virtio_ccw.c
>> @@ -833,6 +833,11 @@ static int virtio_ccw_finalize_features(struct
>> virtio_device *vdev)
>> ret = -ENOMEM;
>> goto out_free;
>> }
>> +
>> + if (is_prot_virt_guest() &&
>> + !__virtio_test_bit(vdev, VIRTIO_F_IOMMU_PLATFORM))
>
> Add a comment, and (maybe) a message?
>
> Otherwise, I think this is fine, as it should fail the probe, which is
> what we want.
yes right a message is needed.
and I extend a little the comment I had before.
thanks
Regards,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
next prev parent reply other threads:[~2020-06-10 15:27 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-10 13:11 [PATCH] s390: protvirt: virtio: Refuse device without IOMMU Pierre Morel
2020-06-10 13:24 ` Cornelia Huck
2020-06-10 14:37 ` Pierre Morel
2020-06-10 14:53 ` Cornelia Huck
2020-06-10 15:27 ` Pierre Morel [this message]
2020-06-10 17:24 ` Halil Pasic
2020-06-11 3:10 ` Jason Wang
2020-06-12 9:21 ` Pierre Morel
2020-06-12 11:38 ` Pierre Morel
2020-06-15 3:01 ` Jason Wang
2020-06-15 10:37 ` Halil Pasic
2020-06-15 11:49 ` Pierre Morel
2020-06-15 11:50 ` Pierre Morel
2020-06-12 13:45 ` Mauricio Tavares
2020-06-12 15:15 ` Pierre Morel
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