search for: ioasid

...bits are important. > > Curious do you see such situation where low end of the address > > space is not usable (since you have both start/end defined later)? > > A start address would allow to provide something resembling a GART to the > guest: an IOMMU with one address space (ioasid_bits=0) and a small IOVA > aperture. I'm not sure how useful that would be in practice. Intel VT-d has no such limitation, which I can tell. :-) > > On a related note, the virtio-iommu itself doesn't provide a > per-address-space aperture as it stands. For example, attaching...

...bits are important. > > Curious do you see such situation where low end of the address > > space is not usable (since you have both start/end defined later)? > > A start address would allow to provide something resembling a GART to the > guest: an IOMMU with one address space (ioasid_bits=0) and a small IOVA > aperture. I'm not sure how useful that would be in practice. Intel VT-d has no such limitation, which I can tell. :-) > > On a related note, the virtio-iommu itself doesn't provide a > per-address-space aperture as it stands. For example, attaching...

> From: Jean-Philippe Brucker > Sent: Saturday, April 8, 2017 3:18 AM > [...] > II. Feature bits > ================ > > VIRTIO_IOMMU_F_INPUT_RANGE (0) > Available range of virtual addresses is described in input_range Usually only the maximum supported address bits are important. Curious do you see such situation where low end of the address space is not usable

> From: Jean-Philippe Brucker > Sent: Saturday, April 8, 2017 3:18 AM > [...] > II. Feature bits > ================ > > VIRTIO_IOMMU_F_INPUT_RANGE (0) > Available range of virtual addresses is described in input_range Usually only the maximum supported address bits are important. Curious do you see such situation where low end of the address space is not usable

This is the initial proposal for a paravirtualized IOMMU device using virtio transport. It contains a description of the device, a Linux driver, and a toy implementation in kvmtool. With this prototype, you can translate DMA to guest memory from emulated (virtio), or passed-through (VFIO) devices. In its simplest form, implemented here, the device handles map/unmap requests from the guest. Future

This is the initial proposal for a paravirtualized IOMMU device using virtio transport. It contains a description of the device, a Linux driver, and a toy implementation in kvmtool. With this prototype, you can translate DMA to guest memory from emulated (virtio), or passed-through (VFIO) devices. In its simplest form, implemented here, the device handles map/unmap requests from the guest. Future

...imum supported address bits are important. > Curious do you see such situation where low end of the address > space is not usable (since you have both start/end defined later)? A start address would allow to provide something resembling a GART to the guest: an IOMMU with one address space (ioasid_bits=0) and a small IOVA aperture. I'm not sure how useful that would be in practice. On a related note, the virtio-iommu itself doesn't provide a per-address-space aperture as it stands. For example, attaching a device to an address space might restrict the available IOVA range for the wh...