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Re: [qemu-s390x] [Qemu-devel] [PATCH for-4.0 v4 2/2] virtio: Provide ver

From: Thomas Huth
Subject: Re: [qemu-s390x] [Qemu-devel] [PATCH for-4.0 v4 2/2] virtio: Provide version-specific variants of virtio PCI devices
Date: Thu, 3 Jan 2019 10:38:18 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1

On 2018-12-05 20:57, Eduardo Habkost wrote:
> Many of the current virtio-*-pci device types actually represent
> 3 different types of devices:
> * virtio 1.0 non-transitional devices
> * virtio 1.0 transitional devices
> * virtio 0.9 ("legacy device" in virtio 1.0 terminology)
> That would be just an annoyance if it didn't break our device/bus
> compatibility QMP interfaces.  With these multi-purpose device
> types, there's no way to tell management software that
> transitional devices and legacy devices require a Conventional
> PCI bus.
> The multi-purpose device types would also prevent us from telling
> management software what's the PCI vendor/device ID for them,
> because their PCI IDs change at runtime depending on the bus
> where they were plugged.
> This patch adds separate device types for each of those virtio
> device flavors:
> - virtio-*-pci: the existing multi-purpose device types
>   - Configurable using `disable-legacy` and `disable-modern`
>     properties
>   - Legacy driver support is automatically enabled/disabled
>     depending on the bus where it is plugged
>   - Supports Conventional PCI and PCI Express buses
>     (but Conventional PCI is incompatible with
>     disable-legacy=off)
>   - Changes PCI vendor/device IDs at runtime
> - virtio-*-pci-transitional: virtio-1.0 device supporting legacy drivers
>   - Supports Conventional PCI buses only, because
>     it has a PIO BAR
> - virtio-*-pci-non-transitional: modern-only
>   - Supports both Conventional PCI and PCI Express buses
> The existing TYPE_* macros for these types will point to an
> abstract base type, so existing casts in the code will keep
> working for all variants.
> A simple test script (tests/acceptance/virtio_version.py) is
> included, to check if the new device types are equivalent to
> using the `disable-legacy` and `disable-modern` options.
> Acked-by: Andrea Bolognani <address@hidden>
> Reviewed-by: Cornelia Huck <address@hidden>
> Signed-off-by: Eduardo Habkost <address@hidden>

 Hi Eduardo,

with these new devices, I can trigger an abort on s390x:

$ qemu-system-s390x -M s390-ccw-virtio-2.5 -monitor stdio -no-shutdown
QEMU 3.1.50 monitor - type 'help' for more information
(qemu) device_add vhost-scsi-pci-non-transitional
qemu-system-s390x: hw/core/qdev-properties.c:1236:
qdev_prop_set_globals: Assertion `prop->user_provided' failed.
Aborted (core dumped)

Any ideas how to fix that?


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