Hi Jean,
On 10/8/20 7:15 PM, Jean-Philippe Brucker wrote:
> From: Bharat Bhushan <[email protected]>
>
> The virtio-iommu device can deal with arbitrary page sizes for virtual
> endpoints, but for endpoints assigned with VFIO it must follow the page
> granule used by the host IOMMU driver.
>
> Implement the interface to set the vIOMMU page size mask, called by VFIO
> for each endpoint. We assume that all host IOMMU drivers use the same
> page granule (the host page granule). Override the page_size_mask field
> in the virtio config space.
>
> Signed-off-by: Bharat Bhushan <[email protected]>
> Signed-off-by: Jean-Philippe Brucker <[email protected]>
> ---
> v10: Use global page mask, allowing VFIO to override it until boot.
> ---
> hw/virtio/virtio-iommu.c | 51 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 51 insertions(+)
>
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index 8823bfc804a..dd0b3093d1b 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -914,6 +914,56 @@ static int
> virtio_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu_mr,
> return 0;
> }
>
> +static int virtio_iommu_set_page_size_mask(IOMMUMemoryRegion *mr,
> + uint64_t page_size_mask,
> + Error **errp)
> +{
> + int new_granule, old_granule;
> + IOMMUDevice *sdev = container_of(mr, IOMMUDevice, iommu_mr);
> + VirtIOIOMMU *s = sdev->viommu;
> +
> + if (!page_size_mask) {
set errp
> + return -1;
> + }
> +
> + new_granule = ctz64(page_size_mask);
> + old_granule = ctz64(s->config.page_size_mask);
I think this would be interesting to add a trace point
> +
> + /*
> + * Modifying the page size after machine initialization isn't supported.
> + * Having a different mask is possible but the guest will use sub-optimal
> + * block sizes, so warn about it.
> + */
> + if (qdev_hotplug) {
> + if (new_granule != old_granule) {
> + error_setg(errp,
> + "virtio-iommu page mask 0x%"PRIx64
> + " is incompatible with mask 0x%"PRIx64,
> + s->config.page_size_mask, page_size_mask);
> + return -1;
> + } else if (page_size_mask != s->config.page_size_mask) {
> + warn_report("virtio-iommu page mask 0x%"PRIx64
> + " does not match 0x%"PRIx64,
> + s->config.page_size_mask, page_size_mask);
> + }
> + return 0;
> + }
> +
> + /*
> + * Disallow shrinking the page size. For example if an endpoint only
> + * supports 64kB pages, we can't globally enable 4kB pages. But that
> + * shouldn't happen, the host is unlikely to setup differing page
> granules.
> + * The other bits are only hints describing optimal block sizes.
> + */
> + if (new_granule < old_granule) {
> + error_setg(errp, "memory region shrinks the virtio-iommu page
> granule");
> + return -1;
> + }
> +
> + s->config.page_size_mask = page_size_mask;
> + return 0;
> +}
> +
> static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
> {
> VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> @@ -1146,6 +1196,7 @@ static void
> virtio_iommu_memory_region_class_init(ObjectClass *klass,
> imrc->translate = virtio_iommu_translate;
> imrc->replay = virtio_iommu_replay;
> imrc->notify_flag_changed = virtio_iommu_notify_flag_changed;
> + imrc->iommu_set_page_size_mask = virtio_iommu_set_page_size_mask;
> }
>
> static const TypeInfo virtio_iommu_info = {
>
Thanks
Eric
