For the case when an IOMMU is used for translating system physical
addresses to DMA bus master addresses, the transport-independent
virtio device drivers will be required to map their VRING areas to
bus addresses with VIRTIO_DEVICE_PROTOCOL.MapSharedBuffer() calls.
- MMIO and legacy virtio transport do not support IOMMU to translate the
addresses hence RingBaseShift will always be set to zero.
- modern virtio transport supports IOMMU to translate the address, in
next patch we will update the Virtio10Dxe to use RingBaseShift offset.
Suggested-by: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
[lersek@redhat.com: remove commit msg paragraph with VirtioLib reference]
[lersek@redhat.com: fix typo in VIRTIO_SET_QUEUE_ADDRESS comment block]
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
53a4c6047f