On Wed, Feb 12, 2020 at 11:39:54AM +0800, Jason Wang wrote: > > On 2020/2/11 下午7:33, Michael S. Tsirkin wrote: > > On Mon, Feb 10, 2020 at 05:05:17PM +0800, Zha Bin wrote: > > > From: Liu Jiang<ge...@linux.alibaba.com> > > > > > > The standard virtio-mmio devices use notification register to signal > > > backend. This will cause vmexits and slow down the performance when we > > > passthrough the virtio-mmio devices to guest virtual machines. > > > We proposed to update virtio over MMIO spec to add the per-queue > > > notify feature VIRTIO_F_MMIO_NOTIFICATION[1]. It can allow the VMM to > > > configure notify location for each queue. > > > > > > [1]https://lkml.org/lkml/2020/1/21/31 > > > > > > Signed-off-by: Liu Jiang<ge...@linux.alibaba.com> > > > Co-developed-by: Zha Bin<zha...@linux.alibaba.com> > > > Signed-off-by: Zha Bin<zha...@linux.alibaba.com> > > > Co-developed-by: Jing Liu<jing2....@linux.intel.com> > > > Signed-off-by: Jing Liu<jing2....@linux.intel.com> > > > Co-developed-by: Chao Peng<chao.p.p...@linux.intel.com> > > > Signed-off-by: Chao Peng<chao.p.p...@linux.intel.com> > > Hmm. Any way to make this static so we don't need > > base and multiplier? > > > E.g page per vq? > > Thanks
Problem is, is page size well defined enough? Are there cases where guest and host page sizes differ? I suspect there might be. But I also think this whole patch is unproven. Is someone actually working on QEMU code to support pass-trough of virtio-pci as virtio-mmio for nested guests? What's the performance gain like? -- MST
