Hi Oleksandr, On Mon, Jun 6, 2022 at 10:16 AM Oleksandr Tyshchenko <olekstysh@xxxxxxxxx> wrote: > The high level idea is to create new Xen’s grant table based DMA-mapping layer for the guest Linux whose main > purpose is to provide a special 64-bit DMA address which is formed by using the grant reference (for a page > to be shared with the backend) with offset and setting the highest address bit (this is for the backend to > be able to distinguish grant ref based DMA address from normal GPA). For this to work we need the ability > to allocate contiguous (consecutive) grant references for multi-page allocations. And the backend then needs > to offer VIRTIO_F_ACCESS_PLATFORM and VIRTIO_F_VERSION_1 feature bits (it must support virtio-mmio modern > transport for 64-bit addresses in the virtqueue). I was trying your series, from Linus's tree now and started seeing boot failures, failed to mount rootfs. And the reason probably is these messages: [ 1.222498] virtio_scsi virtio1: device must provide VIRTIO_F_ACCESS_PLATFORM [ 1.316334] virtio_net virtio0: device must provide VIRTIO_F_ACCESS_PLATFORM I understand from your email that the backends need to offer VIRTIO_F_ACCESS_PLATFORM flag now, but should this requirement be a bit soft ? I mean shouldn't we allow both types of backends to run with the same kernel, ones that offer this feature and others that don't ? The ones that don't offer the feature, should continue to work like they used to, i.e. without the restricted memory access feature. I am testing Xen currently with help of Qemu over my x86 desktop and these backends (scsi and net) are part of QEMU itself I think, and I don't really want to go and make the change there. Thanks. -- Viresh _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
