Jason Wang
2021-Feb-24 09:30 UTC
[PATCH] vdpa/mlx5: set_features should allow reset to zero
On 2021/2/24 4:43 ??, Michael S. Tsirkin wrote:> On Wed, Feb 24, 2021 at 04:26:43PM +0800, Jason Wang wrote: >> Basically on first guest access QEMU would tell kernel whether >> guest is using the legacy or the modern interface. >> E.g. virtio_pci_config_read/virtio_pci_config_write will call ioctl(ENABLE_LEGACY, 1) >> while virtio_pci_common_read will call ioctl(ENABLE_LEGACY, 0) >> >> >> But this trick work only for PCI I think? >> >> Thanks > ccw has a revision it can check. mmio does not have transitional devices > at all.Ok, then we can do the workaround in the qemu, isn't it? Thanks
Michael S. Tsirkin
2021-Feb-28 21:30 UTC
[PATCH] vdpa/mlx5: set_features should allow reset to zero
On Wed, Feb 24, 2021 at 05:30:37PM +0800, Jason Wang wrote:> > On 2021/2/24 4:43 ??, Michael S. Tsirkin wrote: > > On Wed, Feb 24, 2021 at 04:26:43PM +0800, Jason Wang wrote: > > > Basically on first guest access QEMU would tell kernel whether > > > guest is using the legacy or the modern interface. > > > E.g. virtio_pci_config_read/virtio_pci_config_write will call ioctl(ENABLE_LEGACY, 1) > > > while virtio_pci_common_read will call ioctl(ENABLE_LEGACY, 0) > > > > > > > > > But this trick work only for PCI I think? > > > > > > Thanks > > ccw has a revision it can check. mmio does not have transitional devices > > at all. > > > Ok, then we can do the workaround in the qemu, isn't it? > > Thankswhich one do you mean? -- MST
Jason Wang
2021-Mar-01 03:53 UTC
[PATCH] vdpa/mlx5: set_features should allow reset to zero
On 2021/3/1 5:30 ??, Michael S. Tsirkin wrote:> On Wed, Feb 24, 2021 at 05:30:37PM +0800, Jason Wang wrote: >> On 2021/2/24 4:43 ??, Michael S. Tsirkin wrote: >>> On Wed, Feb 24, 2021 at 04:26:43PM +0800, Jason Wang wrote: >>>> Basically on first guest access QEMU would tell kernel whether >>>> guest is using the legacy or the modern interface. >>>> E.g. virtio_pci_config_read/virtio_pci_config_write will call ioctl(ENABLE_LEGACY, 1) >>>> while virtio_pci_common_read will call ioctl(ENABLE_LEGACY, 0) >>>> >>>> >>>> But this trick work only for PCI I think? >>>> >>>> Thanks >>> ccw has a revision it can check. mmio does not have transitional devices >>> at all. >> >> Ok, then we can do the workaround in the qemu, isn't it? >> >> Thanks > which one do you mean?I meant the workaround that is done by 452639a64ad8 ("vdpa: make sure set_features is invoked for legacy"). Thanks>