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Re: [Qemu-devel] [PATCH v4] vhost-user interrupt management fixes
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v4] vhost-user interrupt management fixes |
Date: |
Thu, 18 Feb 2016 12:59:55 +0200 |
On Thu, Feb 18, 2016 at 12:40:36PM +0200, Victor Kaplansky wrote:
> Since guest_mask_notifier can not be used in vhost-user mode due
> to buffering implied by unix control socket, force
> use_mask_notifier on virtio devices of vhost-user interfaces, and
> send correct callfd to the guest at vhost start.
>
> Using guest_notifier_mask function in vhost-user case may
> break interrupt mask paradigm, because mask/unmask is not
> really done when returning from guest_notifier_mask call, instead
> message is posted in a unix socket, and processed later.
>
> Add an option boolean flag 'use_mask_notifier' to disable the use
> of guest_notifier_mask in virtio pci.
>
> Signed-off-by: Didier Pallard <address@hidden>
> Signed-off-by: Victor Kaplansky <address@hidden>
Conflicts with endian cleanup in my tree - can you
rebase pls?
There's also a trailing whitespace somewhere.
> ---
>
> v4 changes:
> In respond to Michael S. Tsirkin comments:
> - changed the name of new field to use_guest_notifier_mask
> - clarified comments
> - vhost_virtqueue_mask() called for unmask
> - cosmetic changes
> - moved the initialization of the new field from virtio_reset
> to virtio_init.
>
> v3 changes:
> In respond to Michael S. Tsirkin comments:
> - vhost_net.c: removed dependency on virtio-pci.h
> - vhost.c: simplified the check for vhost-user backend,
> replaced by checking use_mask_notifier; added comment
> explaining why vring for vhost-user initialized in
> unmasked state;
> - cosmetic fixes.
>
> v2 changes:
> - a new boolean field is added to all virtio devices instead
> of defining a property in some virtio-pci devices.
>
> include/hw/virtio/virtio.h | 1 +
> hw/net/vhost_net.c | 16 ++++++++++++++--
> hw/virtio/vhost.c | 9 +++++++++
> hw/virtio/virtio-pci.c | 14 ++++++++------
> hw/virtio/virtio.c | 1 +
> 5 files changed, 33 insertions(+), 8 deletions(-)
>
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 108cdb0f..c38a2fef 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -90,6 +90,7 @@ struct VirtIODevice
> VMChangeStateEntry *vmstate;
> char *bus_name;
> uint8_t device_endian;
> + bool use_guest_notifier_mask;
> QLIST_HEAD(, VirtQueue) *vector_queues;
> };
>
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 3940a04b..0ca16388 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -306,13 +306,25 @@ int vhost_net_start(VirtIODevice *dev, NetClientState
> *ncs,
> }
>
> for (j = 0; j < total_queues; j++) {
> + struct vhost_net *net;
> +
> r = vhost_net_set_vnet_endian(dev, ncs[j].peer, true);
> if (r < 0) {
> goto err_endian;
> }
> - vhost_net_set_vq_index(get_vhost_net(ncs[j].peer), j * 2);
> - }
>
> + net = get_vhost_net(ncs[j].peer);
> + vhost_net_set_vq_index(net, j * 2);
> +
> + /* Suppress the masking guest notifiers on vhost user
> + * because vhost user doesn't interrupt masking/unmasking
> + * properly.
> + */
> + if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
> + dev->use_guest_notifier_mask = false;
> + }
> + }
> +
> r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
> if (r < 0) {
> error_report("Error binding guest notifier: %d", -r);
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 7dff7554..30467b38 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -855,6 +855,14 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
> /* Clear and discard previous events if any. */
> event_notifier_test_and_clear(&vq->masked_notifier);
>
> + /* Init vring in unmasked state, unless guest_notifier_mask
> + * will do it later.
> + */
> + if (!vdev->use_guest_notifier_mask) {
> + /* TODO: check and handle errors. */
> + vhost_virtqueue_mask(dev, vdev, idx, false);
> + }
> +
> return 0;
>
> fail_kick:
> @@ -1148,6 +1156,7 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev,
> VirtIODevice *vdev, int n,
> struct vhost_vring_file file;
>
> if (mask) {
> + assert(vdev->use_guest_notifier_mask);
> file.fd = event_notifier_get_fd(&hdev->vqs[index].masked_notifier);
> } else {
> file.fd =
> event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 5494ff4a..440776c0 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -806,7 +806,7 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy
> *proxy, int nvqs)
> /* If guest supports masking, set up irqfd now.
> * Otherwise, delay until unmasked in the frontend.
> */
> - if (k->guest_notifier_mask) {
> + if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> ret = kvm_virtio_pci_irqfd_use(proxy, queue_no, vector);
> if (ret < 0) {
> kvm_virtio_pci_vq_vector_release(proxy, vector);
> @@ -822,7 +822,7 @@ undo:
> if (vector >= msix_nr_vectors_allocated(dev)) {
> continue;
> }
> - if (k->guest_notifier_mask) {
> + if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> kvm_virtio_pci_irqfd_release(proxy, queue_no, vector);
> }
> kvm_virtio_pci_vq_vector_release(proxy, vector);
> @@ -849,7 +849,7 @@ static void kvm_virtio_pci_vector_release(VirtIOPCIProxy
> *proxy, int nvqs)
> /* If guest supports masking, clean up irqfd now.
> * Otherwise, it was cleaned when masked in the frontend.
> */
> - if (k->guest_notifier_mask) {
> + if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> kvm_virtio_pci_irqfd_release(proxy, queue_no, vector);
> }
> kvm_virtio_pci_vq_vector_release(proxy, vector);
> @@ -882,7 +882,7 @@ static int virtio_pci_vq_vector_unmask(VirtIOPCIProxy
> *proxy,
> /* If guest supports masking, irqfd is already setup, unmask it.
> * Otherwise, set it up now.
> */
> - if (k->guest_notifier_mask) {
> + if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> k->guest_notifier_mask(vdev, queue_no, false);
> /* Test after unmasking to avoid losing events. */
> if (k->guest_notifier_pending &&
> @@ -905,7 +905,7 @@ static void virtio_pci_vq_vector_mask(VirtIOPCIProxy
> *proxy,
> /* If guest supports masking, keep irqfd but mask it.
> * Otherwise, clean it up now.
> */
> - if (k->guest_notifier_mask) {
> + if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> k->guest_notifier_mask(vdev, queue_no, true);
> } else {
> kvm_virtio_pci_irqfd_release(proxy, queue_no, vector);
> @@ -1022,7 +1022,9 @@ static int virtio_pci_set_guest_notifier(DeviceState
> *d, int n, bool assign,
> event_notifier_cleanup(notifier);
> }
>
> - if (!msix_enabled(&proxy->pci_dev) && vdc->guest_notifier_mask) {
> + if (!msix_enabled(&proxy->pci_dev) &&
> + vdev->use_guest_notifier_mask &&
> + vdc->guest_notifier_mask) {
> vdc->guest_notifier_mask(vdev, n, !assign);
> }
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 90f25451..e365960b 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1677,6 +1677,7 @@ void virtio_init(VirtIODevice *vdev, const char *name,
> vdev->vmstate = qemu_add_vm_change_state_handler(virtio_vmstate_change,
> vdev);
> vdev->device_endian = virtio_default_endian();
> + vdev->use_guest_notifier_mask = true;
> }
>
> hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
> --
> Victor