Hi Anthony - My questions and Comments are in line. Thx,
Venkat -----Original Message----- From: Anthony Liguori [mailto:anth...@codemonkey.ws] Sent: Tuesday, April 28, 2009 8:41 PM To: Avi Kivity Cc: Kumar, Venkat; kvm@vger.kernel.org Subject: Re: FW: Notification from Qemu to Guest Avi Kivity wrote: >> I have emulated a PCI device on Qemu and hooked my sample/simple >> driver to that virtio device on the guest. This is independent of the existing virtio PCI device? ==> No it is the same as the existing virtio PCI device. I am reusing the virtio-blk model. In qemu/hw/pc.c, I am spawning an emulated PCI device like this "virtio_sample_init(pci_bus,drives_table[25].bdrv);". I haven't explored the "blockdrivestate" parameter (second parameter) and hardcoded it to "25" because I don't want to associate the device with an image file on the disk rather I just want use the device for communication. I am manually filling the 25th indexed blockdriverstate in this way. BlockDriverState *bdrv_temp; int idx_tmp; bdrv_temp = bdrv_new("SAMPLE Disk Device"); drives_table[25].bdrv = bdrv_temp; drives_table[25].type = type; drives_table[25].bus = bus_id; drives_table[25].unit = unit_id; drives_table[25].onerror = onerror; nb_drives++; in qemu/vl.c >> As a part of "Kick" routine in my guest driver I could see the >> notification happening from Guest-Qemu and In the Qemu process as a >> part of handle output for the emulated device I am simply doing >> "virtio_notify(vdev, vq)" but I don't see my callback getting called >> which is already registered as a part of "find_vq" in guest driver's >> probe. >> > > You need to enable notifications, not sure how exactly. By default, if you zeroed the memory for the ring, notifications are enabled. You have to set a bit to disable notifications. It sounds like you aren't properly injecting the IRQ which is hard to assess without more detail about what the particular device you've added to QEMU. Are you reusing the existing virtio PCI infrastructure in QEMU? ==> I am using the existing vp_find_vq to allocate virtio queues and rings so I assume this function zeroes the ring memory. As a part of probe in Guest virtio sample driver, I am calling find_vq and kick immediately to test notifications. ============================================================================ static int virtsample_probe(struct virtio_device *vdev) { struct virtio_sample *vsample; int err; printk("Virtio SAMPLE probe is called \n"); if (index_to_minor(index) >= 1 << MINORBITS) return -ENOSPC; vdev->priv = vsample = kmalloc(sizeof(*vsample), GFP_KERNEL); if (!vsample) { err = -ENOMEM; goto out; } INIT_LIST_HEAD(&vsample->reqs); spin_lock_init(&vsample->lock); vsample->vdev = vdev; /* We expect one virtqueue, for output. */ vsample->vq = vdev->config->find_vq(vdev, 0, sample_done); if (IS_ERR(vsample->vq)) { err = PTR_ERR(vsample->vq); goto out_free_vsample; } vsample->vq->vq_ops->kick(vsample->vq); return 0; out_free_vsample: kfree(vsample); printk("Failed in output_free_sample\n"); out: return err; } ============================================================================ And as a part of handle output for kick in the qemu side I am simply calling "virtio_notify" static void virtio_sample_handle_output(VirtIODevice *vdev, VirtQueue *vq) { printf("Function = %s, Line = %d\n",__FUNCTION__,__LINE__); virtio_notify(vdev, vq); } Kick is working fine as I am landing in Qemu when making that call, However virtio_notify is not resulting in my callback invocation registered as part find_vq. Do you see any missing parts here? >> BTW, the emulated device is allocated with "GSI 11" where as for >> other emulated devices like "virtio-blk" is associated with GSI 10 >> which I found in "dmesg's". Is this a reason why interrupt is not >> delivered from Qemu-Guest? >> > > Interrupts for PCI devices are assigned based on the slots where they > sit. Both GSI 10 and GSI 11 are PCI link interrupts. virtio-pci always uses LNK A. How it gets mapped to GSI depends on the slot as Avi mentioned. Regards, Anthony Liguori -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
