On Mon, Dec 17, 2012 at 05:54:06PM +0100, Paolo Bonzini wrote:
> Il 17/12/2012 17:48, Michael S. Tsirkin ha scritto:
> > On Mon, Dec 17, 2012 at 05:24:48PM +0100, Paolo Bonzini wrote:
> >> virtio-pci devices do not perform a full reset when zero is written
> >> to the status byte. While PCI-specific status is initialized, the
> >> reset does not propagate down the qdev bus hierarchy. Because of
> >> this, a virtio reset does not cancel in-flight I/O for virtio-scsi
> >> (where the cancellation is handled automatically by the SCSI
> >> devices underneath virtio-scsi-pci).
> >>
> >> Reported-by: Bryan Venteicher <bry...@daemoninthecloset.org>
> >> Cc: Michael S. Tsirkin <m...@redhat.com>
> >> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> >
> > I would still prefer this logic to reside in virtio.c instead of being
> > duplicated in each bus.
> > My idea was to simply call qdev_reset_all on the binding from virtio.c
> > but other ideas wellcome.
>
> I think you're confusing "in the common superclass of all virtio
> transports" vs "in the common superclass of all virtio devices".
> virtio.c only implements a common superclass of all virtio devices; in
> fact, there is no common superclass of all virtio transports, and it is
> not possible without multiple inheritance or stuff like traits (you're
> already inheriting from PCIDevice for virtio-*-pci).
>
> Such common superclass, if it existed, would abstract stuff like "write
> zero to the status register" and would call qdev_reset_all. But again,
> we don't have this concept.
>
> Paolo
There's some misunderstanding here.
This is not about classes and stuff.
Common code should be in a single place so everyone can reuse it through
function calls, not duplicated in all transports.
And yes we do have examples of this if you are asking for examples;
examples are functions like virtio_reset, virtio_set_status, etc.
> >
> >
> >> ---
> >> hw/virtio-pci.c | 28 ++++++++++------------------
> >> 1 file changed, 10 insertions(+), 18 deletions(-)
> >>
> >> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> >> index a7c75fe..2cf5282 100644
> >> --- a/hw/virtio-pci.c
> >> +++ b/hw/virtio-pci.c
> >> @@ -268,12 +268,10 @@ static void virtio_ioport_write(void *opaque,
> >> uint32_t addr, uint32_t val)
> >> case VIRTIO_PCI_QUEUE_PFN:
> >> pa = (hwaddr)val << VIRTIO_PCI_QUEUE_ADDR_SHIFT;
> >> if (pa == 0) {
> >> - virtio_reset(proxy->vdev);
> >> - virtio_pci_stop_ioeventfd(proxy);
> >> - msix_unuse_all_vectors(&proxy->pci_dev);
> >> - }
> >> - else
> >> + qdev_reset_all(&proxy->pci_dev.qdev);
> >> + } else {
> >> virtio_queue_set_addr(vdev, vdev->queue_sel, pa);
> >> + }
> >> break;
> >> case VIRTIO_PCI_QUEUE_SEL:
> >> if (val < VIRTIO_PCI_QUEUE_MAX)
> >> @@ -285,22 +283,16 @@ static void virtio_ioport_write(void *opaque,
> >> uint32_t addr, uint32_t val)
> >> }
> >> break;
> >> case VIRTIO_PCI_STATUS:
> >> - if (vdev->status == 0) {
> >> - virtio_reset(proxy->vdev);
> >> - }
> >> -
> >> - if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
> >> - virtio_pci_stop_ioeventfd(proxy);
> >> - }
> >> -
> >> virtio_set_status(vdev, val & 0xFF);
> >>
> >> - if (val & VIRTIO_CONFIG_S_DRIVER_OK) {
> >> - virtio_pci_start_ioeventfd(proxy);
> >> - }
> >> -
> >> if (vdev->status == 0) {
> >> - msix_unuse_all_vectors(&proxy->pci_dev);
> >> + qdev_reset_all(&proxy->pci_dev.qdev);
> >> + } else {
> >> + if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
> >> + virtio_pci_stop_ioeventfd(proxy);
> >> + } else {
> >> + virtio_pci_start_ioeventfd(proxy);
> >> + }
> >> }
> >>
> >> /* Linux before 2.6.34 sets the device as OK without enabling
> >> --
> >> 1.8.0.2
> >>
