Re: [PATCH v4 3/4] vdpa: add vdpa-dev support

[Stefano Garzarella <sgarzare@redhat.com>]

On Wed, May 11, 2022 at 04:56:23PM +0800, Jason Wang wrote:
>On Wed, May 11, 2022 at 2:32 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
>>
>> On Wed, May 11, 2022 at 10:56:02AM +0800, Jason Wang wrote:
>> >On Tue, May 10, 2022 at 8:59 PM Longpeng(Mike) <longpeng2@huawei.com> wrote:
>> >>
>> >> From: Longpeng <longpeng2@huawei.com>
>> >>
>> >> Supports vdpa-dev.
>> >>
>> >> Signed-off-by: Longpeng <longpeng2@huawei.com>
>> >> ---
>> >>  hw/virtio/Kconfig            |   5 +
>> >>  hw/virtio/meson.build        |   1 +
>> >>  hw/virtio/vdpa-dev.c         | 385 +++++++++++++++++++++++++++++++++++
>> >>  include/hw/virtio/vdpa-dev.h |  43 ++++
>> >>  4 files changed, 434 insertions(+)
>> >>  create mode 100644 hw/virtio/vdpa-dev.c
>> >>  create mode 100644 include/hw/virtio/vdpa-dev.h
>> >>
>> >> diff --git a/hw/virtio/Kconfig b/hw/virtio/Kconfig
>> >> index c144d42f9b..2723283382 100644
>> >> --- a/hw/virtio/Kconfig
>> >> +++ b/hw/virtio/Kconfig
>> >> @@ -68,3 +68,8 @@ config VHOST_USER_RNG
>> >>      bool
>> >>      default y
>> >>      depends on VIRTIO && VHOST_USER
>> >> +
>> >> +config VHOST_VDPA_DEV
>> >> +    bool
>> >> +    default y if VIRTIO_PCI
>> >
>> >Do we have the plan to add VIRTIO_MMIO support?
>> >
>> >> +    depends on VIRTIO && VHOST_VDPA && LINUX
>> >> diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
>> >> index 67dc77e00f..8f6f86db71 100644
>> >> --- a/hw/virtio/meson.build
>> >> +++ b/hw/virtio/meson.build
>> >> @@ -29,6 +29,7 @@ virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user-i2c.c'))
>> >>  virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_I2C'], if_true: files('vhost-user-i2c-pci.c'))
>> >>  virtio_ss.add(when: 'CONFIG_VHOST_USER_RNG', if_true: files('vhost-user-rng.c'))
>> >>  virtio_ss.add(when: ['CONFIG_VHOST_USER_RNG', 'CONFIG_VIRTIO_PCI'], if_true: files('vhost-user-rng-pci.c'))
>> >> +virtio_ss.add(when: 'CONFIG_VHOST_VDPA_DEV', if_true: files('vdpa-dev.c'))
>> >>
>> >>  virtio_pci_ss = ss.source_set()
>> >>  virtio_pci_ss.add(when: 'CONFIG_VHOST_VSOCK', if_true: files('vhost-vsock-pci.c'))
>> >> diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
>> >> new file mode 100644
>> >> index 0000000000..543b5b4b81
>> >> --- /dev/null
>> >> +++ b/hw/virtio/vdpa-dev.c
>> >> @@ -0,0 +1,385 @@
>> >> +/*
>> >> + * Vhost Vdpa Device
>> >> + *
>> >> + * Copyright (c) Huawei Technologies Co., Ltd. 2022. All Rights Reserved.
>> >> + *
>> >> + * Authors:
>> >> + *   Longpeng <longpeng2@huawei.com>
>> >> + *
>> >> + * Largely based on the "vhost-user-blk-pci.c" and "vhost-user-blk.c" implemented by:
>> >> + *   Changpeng Liu <changpeng.liu@intel.com>
>> >> + *
>> >> + * This work is licensed under the terms of the GNU LGPL, version 2 or later.
>> >> + * See the COPYING.LIB file in the top-level directory.
>> >> + */
>> >> +#include "qemu/osdep.h"
>> >> +#include <sys/ioctl.h>
>> >> +#include <linux/vhost.h>
>> >> +#include "qapi/error.h"
>> >> +#include "qemu/error-report.h"
>> >> +#include "qemu/cutils.h"
>> >> +#include "hw/qdev-core.h"
>> >> +#include "hw/qdev-properties.h"
>> >> +#include "hw/qdev-properties-system.h"
>> >> +#include "hw/virtio/vhost.h"
>> >> +#include "hw/virtio/virtio.h"
>> >> +#include "hw/virtio/virtio-bus.h"
>> >> +#include "hw/virtio/virtio-access.h"
>> >> +#include "hw/virtio/vdpa-dev.h"
>> >> +#include "sysemu/sysemu.h"
>> >> +#include "sysemu/runstate.h"
>> >> +
>> >> +static void
>> >> +vhost_vdpa_device_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>> >> +{
>> >> +    /* Nothing to do */
>> >> +}
>> >> +
>> >> +static uint32_t
>> >> +vhost_vdpa_device_get_u32(int fd, unsigned long int cmd, Error **errp)
>> >> +{
>> >> +    uint32_t val = (uint32_t)-1;
>> >> +
>> >> +    if (ioctl(fd, cmd, &val) < 0) {
>> >> +        error_setg(errp, "vhost-vdpa-device: cmd 0x%lx failed: %s",
>> >> +                   cmd, strerror(errno));
>> >> +    }
>> >> +
>> >> +    return val;
>> >> +}
>> >> +
>> >> +static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
>> >> +{
>> >> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
>> >> +    VhostVdpaDevice *v = VHOST_VDPA_DEVICE(vdev);
>> >> +    uint16_t max_queue_size;
>> >> +    struct vhost_virtqueue *vqs;
>> >> +    int i, ret;
>> >> +
>> >> +    if (!v->vhostdev && v->vhostfd == -1) {
>> >> +        error_setg(errp, "both vhostdev and vhostfd are missing");
>> >> +        return;
>> >> +    }
>> >> +
>> >> +    if (v->vhostdev && v->vhostfd != -1) {
>> >> +        error_setg(errp, "both vhostdev and vhostfd are set");
>> >> +        return;
>> >> +    }
>> >> +
>> >> +    if (v->vhostfd == -1) {
>> >> +        v->vhostfd = qemu_open(v->vhostdev, O_RDWR, errp);
>> >> +        if (*errp) {
>> >
>> >Is this better to set error messages for all the possible failures
>> >during realization?
>> >
>> >> +            return;
>> >> +        }
>> >> +    }
>> >> +    v->vdpa.device_fd = v->vhostfd;
>> >> +
>> >> +    v->vdev_id = vhost_vdpa_device_get_u32(v->vhostfd,
>> >> +                                           VHOST_VDPA_GET_DEVICE_ID, errp);
>> >> +    if (*errp) {
>> >> +        goto out;
>> >> +    }
>> >> +
>> >> +    max_queue_size = vhost_vdpa_device_get_u32(v->vhostfd,
>> >> +                                               VHOST_VDPA_GET_VRING_NUM, errp);
>> >> +    if (*errp) {
>> >> +        goto out;
>> >> +    }
>> >> +
>> >> +    if (v->queue_size > max_queue_size) {
>> >> +        error_setg(errp, "vhost-vdpa-device: invalid queue_size: %u (max:%u)",
>> >> +                   v->queue_size, max_queue_size);
>> >> +        goto out;
>> >> +    } else if (!v->queue_size) {
>> >> +        v->queue_size = max_queue_size;
>> >> +    }
>> >> +
>> >> +    v->num_queues = vhost_vdpa_device_get_u32(v->vhostfd,
>> >> +                                              VHOST_VDPA_GET_VQS_COUNT, errp);
>> >> +    if (*errp) {
>> >> +        goto out;
>> >> +    }
>> >> +
>> >> +    if (!v->num_queues || v->num_queues > VIRTIO_QUEUE_MAX) {
>> >> +        error_setg(errp, "invalid number of virtqueues: %u (max:%u)",
>> >> +                   v->num_queues, VIRTIO_QUEUE_MAX);
>> >> +        goto out;
>> >> +    }
>> >> +
>> >> +    v->dev.nvqs = v->num_queues;
>> >> +    vqs = g_new0(struct vhost_virtqueue, v->dev.nvqs);
>> >> +    v->dev.vqs = vqs;
>> >> +    v->dev.vq_index = 0;
>> >> +    v->dev.vq_index_end = v->dev.nvqs;
>> >> +    v->dev.backend_features = 0;
>> >> +    v->started = false;
>> >> +
>> >> +    ret = vhost_dev_init(&v->dev, &v->vdpa, VHOST_BACKEND_TYPE_VDPA, 0, NULL);
>> >> +    if (ret < 0) {
>> >> +        error_setg(errp, "vhost-vdpa-device: vhost initialization failed: %s",
>> >> +                   strerror(-ret));
>> >> +        goto free_vqs;
>> >> +    }
>> >> +
>> >> +    v->config_size = vhost_vdpa_device_get_u32(v->vhostfd,
>> >> +                                               VHOST_VDPA_GET_CONFIG_SIZE, errp);
>> >> +    if (*errp) {
>> >> +        goto vhost_cleanup;
>> >> +    }
>> >> +
>> >> +    if (v->post_init && v->post_init(v, errp) < 0) {
>> >> +        goto free_virtio;
>> >> +    }
>> >> +
>> >> +    v->config = g_malloc0(v->config_size);
>> >> +
>> >> +    ret = vhost_dev_get_config(&v->dev, v->config, v->config_size, NULL);
>> >> +    if (ret < 0) {
>> >> +        error_setg(errp, "vhost-vdpa-device: get config failed");
>> >> +        goto free_config;
>> >> +    }
>> >> +
>> >> +    virtio_init(vdev, "vhost-vdpa", v->vdev_id, v->config_size);
>> >> +
>> >> +    v->virtqs = g_new0(VirtQueue *, v->dev.nvqs);
>> >> +    for (i = 0; i < v->dev.nvqs; i++) {
>> >> +        v->virtqs[i] = virtio_add_queue(vdev, v->queue_size,
>> >> +                                        vhost_vdpa_device_dummy_handle_output);
>> >> +    }
>> >> +
>> >> +    return;
>> >> +
>> >> +free_virtio:
>> >> +    for (i = 0; i < v->num_queues; i++) {
>> >> +        virtio_delete_queue(v->virtqs[i]);
>> >> +    }
>> >> +    g_free(v->virtqs);
>> >> +    virtio_cleanup(vdev);
>> >> +free_config:
>> >> +    g_free(v->config);
>> >> +vhost_cleanup:
>> >> +    vhost_dev_cleanup(&v->dev);
>> >> +free_vqs:
>> >> +    g_free(vqs);
>> >> +out:
>> >> +    qemu_close(v->vhostfd);
>> >> +    v->vhostfd = -1;
>> >> +}
>> >> +
>> >> +static void vhost_vdpa_device_unrealize(DeviceState *dev)
>> >> +{
>> >> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
>> >> +    VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
>> >> +    int i;
>> >> +
>> >> +    virtio_set_status(vdev, 0);
>> >> +
>> >> +    for (i = 0; i < s->num_queues; i++) {
>> >> +        virtio_delete_queue(s->virtqs[i]);
>> >> +    }
>> >> +    g_free(s->virtqs);
>> >> +    virtio_cleanup(vdev);
>> >> +
>> >> +    g_free(s->config);
>> >> +    g_free(s->dev.vqs);
>> >> +    vhost_dev_cleanup(&s->dev);
>> >> +    qemu_close(s->vhostfd);
>> >> +    s->vhostfd = -1;
>> >> +}
>> >> +
>> >> +static void
>> >> +vhost_vdpa_device_get_config(VirtIODevice *vdev, uint8_t *config)
>> >> +{
>> >> +    VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
>> >> +
>> >> +    memcpy(config, s->config, s->config_size);
>> >> +}
>> >> +
>> >> +static void
>> >> +vhost_vdpa_device_set_config(VirtIODevice *vdev, const uint8_t *config)
>> >> +{
>> >> +    VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
>> >> +    int ret;
>> >> +
>> >> +    ret = vhost_dev_set_config(&s->dev, s->config, 0, s->config_size,
>> >> +                               VHOST_SET_CONFIG_TYPE_MASTER);
>> >> +    if (ret) {
>> >> +        error_report("set device config space failed");
>> >> +        return;
>> >> +    }
>> >> +}
>> >> +
>> >> +static uint64_t vhost_vdpa_device_get_features(VirtIODevice *vdev,
>> >> +                                               uint64_t features,
>> >> +                                               Error **errp)
>> >> +{
>> >> +    VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
>> >> +    uint64_t backend_features = s->dev.features;
>> >> +
>> >> +    if (!virtio_has_feature(features, VIRTIO_F_IOMMU_PLATFORM)) {
>> >> +        virtio_clear_feature(&backend_features, VIRTIO_F_IOMMU_PLATFORM);
>> >> +    }
>> >> +
>> >> +    return backend_features;
>> >> +}
>> >> +
>> >> +static int vhost_vdpa_device_start(VirtIODevice *vdev, Error **errp)
>> >> +{
>> >> +    VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
>> >> +    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
>> >> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>> >> +    int i, ret;
>> >> +
>> >> +    if (!k->set_guest_notifiers) {
>> >> +        error_setg(errp, "binding does not support guest notifiers");
>> >> +        return -ENOSYS;
>> >> +    }
>> >> +
>> >> +    ret = vhost_dev_enable_notifiers(&s->dev, vdev);
>> >> +    if (ret < 0) {
>> >> +        error_setg_errno(errp, -ret, "Error enabling host notifiers");
>> >> +        return ret;
>> >> +    }
>> >> +
>> >> +    ret = k->set_guest_notifiers(qbus->parent, s->dev.nvqs, true);
>> >> +    if (ret < 0) {
>> >> +        error_setg_errno(errp, -ret, "Error binding guest notifier");
>> >> +        goto err_host_notifiers;
>> >> +    }
>> >> +
>> >> +    s->dev.acked_features = vdev->guest_features;
>> >> +
>> >> +    ret = vhost_dev_start(&s->dev, vdev);
>> >> +    if (ret < 0) {
>> >> +        error_setg_errno(errp, -ret, "Error starting vhost");
>> >> +        goto err_guest_notifiers;
>> >> +    }
>> >> +    s->started = true;
>> >> +
>> >> +    /*
>> >> +     * guest_notifier_mask/pending not used yet, so just unmask
>> >> +     * everything here. virtio-pci will do the right thing by
>> >> +     * enabling/disabling irqfd.
>> >> +     */
>> >> +    for (i = 0; i < s->dev.nvqs; i++) {
>> >> +        vhost_virtqueue_mask(&s->dev, vdev, i, false);
>> >> +    }
>> >> +
>> >> +    return ret;
>> >> +
>> >> +err_guest_notifiers:
>> >> +    k->set_guest_notifiers(qbus->parent, s->dev.nvqs, false);
>> >> +err_host_notifiers:
>> >> +    vhost_dev_disable_notifiers(&s->dev, vdev);
>> >> +    return ret;
>> >> +}
>> >> +
>> >> +static void vhost_vdpa_device_stop(VirtIODevice *vdev)
>> >> +{
>> >> +    VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
>> >> +    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
>> >> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>> >> +    int ret;
>> >> +
>> >> +    if (!s->started) {
>> >> +        return;
>> >> +    }
>> >> +    s->started = false;
>> >> +
>> >> +    if (!k->set_guest_notifiers) {
>> >> +        return;
>> >> +    }
>> >> +
>> >> +    vhost_dev_stop(&s->dev, vdev);
>> >> +
>> >> +    ret = k->set_guest_notifiers(qbus->parent, s->dev.nvqs, false);
>> >> +    if (ret < 0) {
>> >> +        error_report("vhost guest notifier cleanup failed: %d", ret);
>> >> +        return;
>> >> +    }
>> >> +
>> >> +    vhost_dev_disable_notifiers(&s->dev, vdev);
>> >> +}
>> >> +
>> >> +static void vhost_vdpa_device_set_status(VirtIODevice *vdev, uint8_t status)
>> >> +{
>> >> +    VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
>> >> +    bool should_start = virtio_device_started(vdev, status);
>> >> +    Error *local_err = NULL;
>> >> +    int ret;
>> >> +
>> >> +    if (!vdev->vm_running) {
>> >> +        should_start = false;
>> >> +    }
>> >> +
>> >> +    if (s->started == should_start) {
>> >> +        return;
>> >> +    }
>> >> +
>> >> +    if (should_start) {
>> >> +        ret = vhost_vdpa_device_start(vdev, &local_err);
>> >> +        if (ret < 0) {
>> >> +            error_reportf_err(local_err, "vhost-vdpa-device: start failed: ");
>> >> +        }
>> >> +    } else {
>> >> +        vhost_vdpa_device_stop(vdev);
>> >> +    }
>> >> +}
>> >> +
>> >> +static Property vhost_vdpa_device_properties[] = {
>> >> +    DEFINE_PROP_STRING("vhostdev", VhostVdpaDevice, vhostdev),
>> >> +    DEFINE_PROP_INT32("vhostfd", VhostVdpaDevice, vhostfd, -1),
>> >
>> >This is probably not needed since we can "abuse" /dev/fd/X for
>> >vhostdev.
>>
>> IIRC for other vhost devices (e.g. vhost-vsock) the management layer
>> (e.g. libvirt) opens the device (because I think QEMU has less
>> permissions) and then passes the fd to QEMU, could this be useful for
>> this scenario as well?
>
>Yes, it's the way current vhost-vDPA did (the fd is passing via SCM_RIGHTS).

Okay, I looked at qemu_open() and I see what you mean. Basically libvirt 
can pass the fd directly with vhostdev=/dev/fdset/X instead of having a 
dedicated property.

I did not know that, I agree to remove "vhostfd" then!

Thanks for the clarification,
Stefano