Re: [PATCH v3 0/4] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[Jean-Philippe Brucker]

On Tue, Feb 15, 2022 at 10:25:21AM +0100, Eric Auger wrote:
> Hi Jean,
> 
> On 2/14/22 1:43 PM, Jean-Philippe Brucker wrote:
> > Replace the VIRTIO_IOMMU_F_BYPASS feature with
> > VIRTIO_IOMMU_F_BYPASS_CONFIG, which enables a config space bit to switch
> > global bypass on and off.
> >
> > Add a boot-bypass option, which defaults to 'on' to be in line with
> > other vIOMMUs and to allow running firmware/bootloader that are unaware
> > of the IOMMU. x86 doesn't need a workaround to boot with virtio-iommu
> > anymore.
> >
> > Since v2 [1]:
> > * Added the new bypass bits to the migration stream.
> >   As discussed on the v2 thread, we assume that cross-version
> >   compatibility is not required for live migration at the moment, so we
> >   only increase the version number. Patch 2 says: "We add the bypass
> >   field to the migration stream without introducing subsections, based
> >   on the assumption that this virtio-iommu device isn't being used in
> >   production enough to require cross-version migration at the moment
> >   (all previous version required workarounds since they didn't support
> >   ACPI and boot-bypass)."
> >
> > [1] 
> > https://lore.kernel.org/qemu-devel/20220127142940.671333-1-jean-philippe@linaro.org/
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Tested-by: Eric Auger <eric.auger@redhat.com>
> 
> I tested both the boot bypass feature with virtio-blk-pci,
> virtio-net-pci and virtio-gpu-pci and migration.

Thanks!

Jean