Re: [PATCH 0/5] Convert virtio-iommu to domain_alloc_paging()

Jacob Pan
2025-02-12T17:05:37Z

Hi Jean-Philippe,

On Wed, 12 Feb 2025 11:58:45 +0000
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:

> Hi Jacob,
>
> On Tue, Feb 11, 2025 at 04:41:51PM -0800, Jacob Pan wrote:
> > > However, there seem to be some unrelated qemu bugs. 7.0.0 does not
> > > have working VIRTIO_IOMMU_F_BYPASS_CONFIG and neither qemu works
> > > with an IDENTITY domain using !VIRTIO_IOMMU_F_BYPASS_CONFIG. It
> > > prints:
> > >
> > > qemu-system-x86_64: iommu has granularity incompatible with
> > > target AS qemu-system-x86_64: iommu map to non memory area
> > > 80000000 qemu-system-x86_64: iommu map to non memory area c0000000
> > > qemu-system-x86_64: iommu map to non memory area e0000000
> > > qemu-system-x86_64: iommu map to non memory area f0000000
> > > qemu-system-x86_64: iommu map to non memory area f8000000
> > > qemu-system-x86_64: iommu map to non memory area fc000000
> > > qemu-system-x86_64: iommu map to non memory area fe000000
> > > qemu-system-x86_64: iommu map to non memory area fe800000
> > > qemu-system-x86_64: iommu map to non memory area 0
> > > qemu-system-x86_64: iommu map to non memory area fef00000
> > > qemu-system-x86_64: iommu map to non memory area ff000000
> > > qemu-system-x86_64: iommu has granularity incompatible with
> > > target AS qemu-system-x86_64: iommu map to non memory area
> > > 200000000 qemu-system-x86_64: iommu map to non memory area
> > > 400000000 qemu-system-x86_64: iommu map to non memory area
> > > 800000000 qemu-system-x86_64: iommu map to non memory area
> > > 1000000000 qemu-system-x86_64: iommu map to non memory area
> > > 2000000000 qemu-system-x86_64: iommu map to non memory area
> > > 4000000000
> >
> > I see the same on arm64 with v9.0, assigned an ixgbe nic via VFIO.
> >
> > qemu-system-aarch64: iommu map to non memory area 0
> > qemu-system-aarch64: iommu map to non memory area 8100000
> > qemu-system-aarch64: iommu map to non memory area 8200000
> > qemu-system-aarch64: iommu map to non memory area 8400000
> > qemu-system-aarch64: iommu map to non memory area 8800000
> > qemu-system-aarch64: iommu map to non memory area 0
> > qemu-system-aarch64: iommu map to non memory area 0
> > qemu-system-aarch64: iommu map to non memory area c000000
> > qemu-system-aarch64: iommu map to non memory area 10000000
> > qemu-system-aarch64: iommu map to non memory area 20000000
> > qemu-system-aarch64: iommu has granularity incompatible with target
> > AS qemu-system-aarch64: iommu map to non memory area 200000000
> > qemu-system-aarch64: iommu map to non memory area 400000000
> > qemu-system-aarch64: iommu map to non memory area 800000000
> > qemu-system-aarch64: iommu map to non memory area 1000000000
> > qemu-system-aarch64: iommu map to non memory area 2000000000
> > qemu-system-aarch64: iommu map to non memory area 4000000000
> > qemu-system-aarch64: iommu map to non memory area 8000000000
> > qemu-system-aarch64: iommu map to non memory area 10000000000
> > qemu-system-aarch64: iommu map to non memory area 20000000000
> > qemu-system-aarch64: iommu map to non memory area 40000000000
> > qemu-system-aarch64: iommu map to non memory area 80000000000
> > qemu-system-aarch64: iommu map to non memory area 100000000000
> > qemu-system-aarch64: iommu map to non memory area 200000000000
> > qemu-system-aarch64: iommu map to non memory area 400000000000
> > qemu-system-aarch64: iommu map to non memory area 800000000000
>
> QEMU v9.0 and v9.1 have reached end of life. Do you also get this
> error with QEMU v9.2.x?
have not tried. will do.

> Are you running an arm64 guest on an x86 host with TCG, or arm64
> guest on arm64 host with KVM?
This is arm64 guest and host.

> Does reproducing this require
> modifying QEMU or Linux to disable support for F_BYPASS_CONFIG, or
> just passing QEMU/kernel parameters?
I only modified guest code to pretend F_BYPASS_CONFIG is not supported,
a couple of places like:

- if (virtio_has_feature(viommu->vdev,
VIRTIO_IOMMU_F_BYPASS_CONFIG)) {
+ if (!virtio_has_feature(viommu->vdev,
VIRTIO_IOMMU_F_BYPASS_CONFIG)) {

Is there a QEMU command line option to disable
VIRTIO_IOMMU_F_BYPASS_CONFIG?