From: David Hildenbrand <david@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Janosch Frank <frankja@linux.ibm.com>,
cohuck@redhat.com, qemu-devel@nongnu.org,
Halil Pasic <pasic@linux.ibm.com>,
borntraeger@de.ibm.com, qemu-s390x@nongnu.org
Subject: Re: [PATCH v5 07/18] s390x: protvirt: Inhibit balloon when switching to protected mode
Date: Tue, 31 Mar 2020 10:59:08 +0200 [thread overview]
Message-ID: <51db0568-c0ce-58b4-93d5-145f91091fb6@redhat.com> (raw)
In-Reply-To: <20200329104114-mutt-send-email-mst@kernel.org>
>> I would have thought we would have to disallow on the hypervisor/device
>> side. (no expert on user space drivers, especially how they
>> detect/enable/access virtio devices)
>
> QEMU does exactly this:
>
> static int virtio_validate_features(VirtIODevice *vdev)
> {
> VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
>
> if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
> !virtio_vdev_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
> return -EFAULT;
> }
> ...
> }
Okay, that makes sense. Thanks!
>
>
>>>
>>> Maybe we need a separate feature bit for this kind of thing where you
>>> assume the driver is trusted? Such a bit - unlike
>>> VIRTIO_F_IOMMU_PLATFORM - would allow legacy guests ...
>>
>> Let's take virtio-mem as an example. You cannot zap memory outside of
>> the scope of a virtio-mem device. So I assume having a user space driver
>> would be ok (although most probably of limited use :) )?
>>
>> Still, for virtio-mem, special s390x handling, similar to virtio-balloon
>> - (un)sharing of pages - would have to be performed.
>>
>> So some feature bits to cleanly separate the different limitations would
>> be great. At least in regard to s390x, I guess we don't have to worry
>> too much about legacy guests.
>
> So if you have the cycles to think through and document how balloon
> interacts with different access limitations, that would be great!
I'll add it to my ever-growing todo list. Would be great if Halil could
help out thinking how to express the semantics so we can handle PV
properly (both, virtio-balloon, but also virtio-mem).
Cheers!
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-03-31 8:59 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 12:20 [PATCH v5 00/18] s390x: Protected Virtualization support Janosch Frank
2020-02-26 12:20 ` [PATCH v5 01/18] s390x: Use constant for ESA PSW address Janosch Frank
2020-02-26 13:46 ` Christian Borntraeger
2020-02-26 13:47 ` Janosch Frank
2020-02-26 14:27 ` David Hildenbrand
2020-02-26 17:51 ` Cornelia Huck
2020-02-26 17:52 ` David Hildenbrand
2020-02-27 7:53 ` Janosch Frank
2020-02-27 8:09 ` Janosch Frank
2020-02-27 9:06 ` Cornelia Huck
2020-02-27 9:23 ` [PATCH v6] s390x: Rename and use constants for short PSW address and mask Janosch Frank
2020-02-27 9:27 ` David Hildenbrand
2020-02-27 10:36 ` Cornelia Huck
2020-02-26 12:20 ` [PATCH v5 02/18] Sync pv Janosch Frank
2020-02-26 12:20 ` [PATCH v5 03/18] s390x: protvirt: Add diag308 subcodes 8 - 10 Janosch Frank
2020-02-26 12:20 ` [PATCH v5 04/18] s390x: protvirt: Support unpack facility Janosch Frank
2020-02-26 12:20 ` [PATCH v5 05/18] s390x: protvirt: Add migration blocker Janosch Frank
2020-02-26 14:05 ` Christian Borntraeger
2020-02-26 14:08 ` Janosch Frank
2020-02-26 12:20 ` [PATCH v5 06/18] s390x: protvirt: Handle diag 308 subcodes 0,1,3,4 Janosch Frank
2020-02-26 15:00 ` Christian Borntraeger
2020-02-26 15:11 ` Janosch Frank
2020-02-26 12:20 ` [PATCH v5 07/18] s390x: protvirt: Inhibit balloon when switching to protected mode Janosch Frank
2020-02-26 14:59 ` David Hildenbrand
2020-02-26 15:06 ` Christian Borntraeger
2020-02-26 15:16 ` David Hildenbrand
2020-02-26 15:30 ` Janosch Frank
2020-02-26 15:31 ` David Hildenbrand
2020-02-26 18:24 ` Cornelia Huck
2020-03-03 12:42 ` Christian Borntraeger
2020-02-26 15:11 ` Janosch Frank
2020-02-26 15:13 ` Christian Borntraeger
2020-02-26 15:15 ` David Hildenbrand
2020-02-27 12:24 ` Halil Pasic
2020-03-19 13:42 ` Halil Pasic
2020-03-19 13:54 ` David Hildenbrand
2020-03-19 15:40 ` Halil Pasic
2020-03-19 17:31 ` David Hildenbrand
2020-03-20 18:43 ` Halil Pasic
2020-03-24 21:07 ` Brijesh Singh
2020-03-27 10:50 ` David Hildenbrand
2020-03-19 17:45 ` Michael S. Tsirkin
2020-03-20 9:36 ` David Hildenbrand
2020-03-29 14:48 ` Michael S. Tsirkin
2020-03-31 8:59 ` David Hildenbrand [this message]
2020-02-26 12:20 ` [PATCH v5 08/18] s390x: protvirt: KVM intercept changes Janosch Frank
2020-02-26 12:20 ` [PATCH v5 09/18] s390x: Add SIDA memory ops Janosch Frank
2020-02-26 12:20 ` [PATCH v5 10/18] s390x: protvirt: Move STSI data over SIDAD Janosch Frank
2020-02-26 12:20 ` [PATCH v5 11/18] s390x: protvirt: SCLP interpretation Janosch Frank
2020-02-26 12:20 ` [PATCH v5 12/18] s390x: protvirt: Set guest IPL PSW Janosch Frank
2020-02-26 12:20 ` [PATCH v5 13/18] s390x: protvirt: Move diag 308 data over SIDAD Janosch Frank
2020-02-26 12:20 ` [PATCH v5 14/18] s390x: protvirt: Disable address checks for PV guest IO emulation Janosch Frank
2020-02-26 12:20 ` [PATCH v5 15/18] s390x: protvirt: Move IO control structures over SIDA Janosch Frank
2020-02-26 12:20 ` [PATCH v5 16/18] s390x: protvirt: Handle SIGP store status correctly Janosch Frank
2020-02-26 12:20 ` [PATCH v5 17/18] s390x: Add unpack facility feature to GA1 Janosch Frank
2020-02-26 12:20 ` [PATCH v5 18/18] docs: Add protvirt docs Janosch Frank
2020-02-26 20:09 ` [PATCH v5 00/18] s390x: Protected Virtualization support Cornelia Huck
2020-02-27 8:32 ` Janosch Frank
2020-03-03 15:50 ` [PATCH] pc-bios: s390x: Save iplb location in lowcore Janosch Frank
2020-03-03 16:13 ` David Hildenbrand
2020-03-04 8:59 ` Janosch Frank
2020-03-04 9:05 ` David Hildenbrand
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