On Mon, Jan 26, 2026 at 10:50:20 +0100, Michal Privoznik via Devel wrote:
> From: Michal Privoznik <[email protected]>
>
> Just like with other features, check whether QEMU supports them
> based on capabilities. Now, instead of inventing a new QEMU
> capability, an existing one can be used:
> QEMU_CAPS_VIRTIO_IOMMU_AW_BITS.
>
> This is because the aw-bits and granule attributes were
> introduced into QEMU in close succession (v9.0.0-rc0~9^2~7
> v9.0.0-rc0~9^2~11), neither can be disabled at compile time and
> backporting just one without the other makes almost no sense.
>
> Signed-off-by: Michal Privoznik <[email protected]>
> ---
> src/qemu/qemu_validate.c | 30 +++++++++++++++++++++---------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
> index 8f85334cf9..6b44d8d785 100644
> --- a/src/qemu/qemu_validate.c
> +++ b/src/qemu/qemu_validate.c
> @@ -5685,15 +5685,27 @@ qemuValidateDomainDeviceDefIOMMU(const
> virDomainIOMMUDef *iommu,
> return -1;
> }
>
> - /* QEMU supports only 4KiB, 8KiB, 16KiB and 64KiB granule size */
> - if (iommu->granule > 0 &&
> - !(iommu->granule == 4 ||
> - iommu->granule == 8 ||
> - iommu->granule == 16 ||
> - iommu->granule == 64)) {
> - virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> - _("iommu: unsupported granule size. Supported values
> are 4, 8, 16 and 64 KiB"));
> - return -1;
> + if (iommu->granule > 0) {
> + /* QEMU supports only 4KiB, 8KiB, 16KiB and 64KiB granule size */
> + if (!(iommu->granule == 4 ||
> + iommu->granule == 8 ||
> + iommu->granule == 16 ||
> + iommu->granule == 64)) {
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> + _("iommu: unsupported granule size. Supported
> values are 4, 8, 16 and 64 KiB"));
> + return -1;
> + }
Consider applying the above diff (obviously including the closing curly
bracket) to the previous patch.
> +
> + /* While the QEMU_CAPS_VIRTIO_IOMMU_AW_BITS tracks .aw-bits
> attribute of
> + * virtio-iommu it is also a good indicator of .granule attribute as
> both
> + * attributes were introduced in neighboring commits, in the same
> release,
> + * neither can be disabled at compile time and backporting one
> without the
> + * other makes no sense. */
> + if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_IOMMU_AW_BITS)) {
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> + _("iommu: page granule is not supported with this
> QEMU binary"));
> + return -1;
> + }
> }
>
> return 0;
> --
> 2.52.0
>
Reviewed-by: Peter Krempa <[email protected]>
