On Tue, Apr 11, 2023 at 2:36 PM Angus Chen <angus.chen@xxxxxxxxxxxxxxx> wrote: > > Hi. > > > -----Original Message----- > > From: Jason Wang <jasowang@xxxxxxxxxx> > > Sent: Tuesday, April 11, 2023 1:24 PM > > To: Angus Chen <angus.chen@xxxxxxxxxxxxxxx> > > Cc: mst@xxxxxxxxxx; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; > > linux-kernel@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH] virtio_pci: Wait for legacy device to be reset > > > > On Tue, Apr 11, 2023 at 9:39 AM Angus Chen <angus.chen@xxxxxxxxxxxxxxx> > > wrote: > > > > > > We read the status of device after reset, > > > It is not guaranteed that the device be reseted successfully. > > > We can use a while loop to make sure that,like the modern device did. > > > The spec is not request it ,but it work. > > > > The only concern is if it's too late to do this. > > > > Btw, any reason you want to have a legacy hardware implementation. It > > will be very tricky to work correctly. > En,I found this in the real production environment some times about one year ago. > and I fix this out of tree.our virtio card had been sold about thousands . > > Now,we created a new card, it support virtio 0.95,1.0,1.1 etc. > And we use this host vdpa+ legacy virtio in vm to hot migration,we found that the > Legacy model often get the middle state value after reset and probe again. > The Soc is Simulated by fpga which is run slower than the host,so the same bug > Is found more frequently when the host use the other kernel like ubuntu or centos8. > > So we hope we can fix this by upstream . I think you can do mediation in your hypervisor. When trapping set_status(), the hypervisor will not return until it reads 0 from the hardware? Thanks > > > > Thanks > > > > > > > > Signed-off-by: Angus Chen <angus.chen@xxxxxxxxxxxxxxx> > > > --- > > > drivers/virtio/virtio_pci_legacy.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c > > > index 2257f1b3d8ae..f2d241563e4f 100644 > > > --- a/drivers/virtio/virtio_pci_legacy.c > > > +++ b/drivers/virtio/virtio_pci_legacy.c > > > @@ -14,6 +14,7 @@ > > > * Michael S. Tsirkin <mst@xxxxxxxxxx> > > > */ > > > > > > +#include <linux/delay.h> > > > #include "linux/virtio_pci_legacy.h" > > > #include "virtio_pci_common.h" > > > > > > @@ -97,7 +98,8 @@ static void vp_reset(struct virtio_device *vdev) > > > vp_legacy_set_status(&vp_dev->ldev, 0); > > > /* Flush out the status write, and flush in device writes, > > > * including MSi-X interrupts, if any. */ > > > - vp_legacy_get_status(&vp_dev->ldev); > > > + while (vp_legacy_get_status(&vp_dev->ldev)) > > > + msleep(1); > > > /* Flush pending VQ/configuration callbacks. */ > > > vp_synchronize_vectors(vdev); > > > } > > > -- > > > 2.25.1 > > > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
