Re: [pve-devel] [PATCH qemu-server v2 1/4] fix #6608: expose viommu driver aw-bits option

["Daniel Kral" <d.kral@proxmox.com>]

On Tue Sep 2, 2025 at 1:21 PM CEST, Daniel Kral wrote:
> Since QEMU 9.2 [0], the default I/O address space bit width was raised
> from 39 bits to 48 bits for the Intel vIOMMU driver, which makes the
> aw-bits check introduced in [1] to trip for host CPUs with less than 48
> bits physical address width from QEMU 9.2 onwards:
>
> vfio 0000:XX:YY.Z: Failed to set vIOMMU: aw-bits 48 > host aw-bits 39
>
> For VFIO devices where a vIOMMU is in-use, QEMU fetches the IOVA ranges
> with the iommufd ioctl IOMMU_IOAS_IOVA_RANGES or the vfio_iommu_type1's
> VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE info, so 'phys-bits' doesn't change
> the behavior of the check.
>
> Therefore, expose the 'aw-bits' option of the intel-iommu and
> virtio-iommu QEMU drivers to allow users to set the value.
>
> [0] https://lore.kernel.org/qemu-devel/20241212083757.605022-17-zhenzhong.duan@intel.com/
> [1] https://lore.kernel.org/qemu-devel/20240605083043.317831-18-zhenzhong.duan@intel.com/
>
> Signed-off-by: Daniel Kral <d.kral@proxmox.com>

This patch is superseded by v3 [0].

For the rest of the series, I'll follow up later, just wanted to get
this out to users sooner than later ;).

[0] https://lore.proxmox.com/pve-devel/20250905141529.215689-1-d.kral@proxmox.com/


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