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Date: Fri, 1 Jun 2018 06:47:01 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Tiwei Bie <tiwei.bie@...el.com>
Cc: bhelgaas@...gle.com, virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, virtio-dev@...ts.oasis-open.org,
linux-pci@...r.kernel.org, dan.daly@...el.com,
mark.d.rustad@...el.com, alexander.h.duyck@...el.com,
cunming.liang@...el.com, zhihong.wang@...el.com
Subject: Re: [PATCH v2] virtio_pci: support enabling VFs
On Fri, Jun 01, 2018 at 10:09:21AM +0800, Tiwei Bie wrote:
> There is a new feature bit allocated in virtio spec to
> support SR-IOV (Single Root I/O Virtualization):
>
> https://github.com/oasis-tcs/virtio-spec/issues/11
>
> This patch enables the support for this feature bit in
> virtio driver.
>
> Signed-off-by: Tiwei Bie <tiwei.bie@...el.com>
> Acked-by: Stefan Hajnoczi <stefanha@...hat.com>
> Acked-by: Michael S. Tsirkin <mst@...hat.com>
> ---
Generally you aren't supposed to carry forward acks
when you make major changes.
In this case I'm fine with the patch, so never mind.
> v2:
> - Disable VFs when unbinding the driver (Alex, MST);
> - Don't use pci_sriov_configure_simple (Alex);
>
> drivers/virtio/virtio_pci_common.c | 30 ++++++++++++++++++++++++++++++
> drivers/virtio/virtio_pci_modern.c | 14 ++++++++++++++
> include/uapi/linux/virtio_config.h | 7 ++++++-
> 3 files changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index 48d4d1cf1cb6..1d4467b2dc31 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -577,6 +577,8 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
> struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> struct device *dev = get_device(&vp_dev->vdev.dev);
>
> + pci_disable_sriov(pci_dev);
> +
> unregister_virtio_device(&vp_dev->vdev);
>
> if (vp_dev->ioaddr)
> @@ -588,6 +590,33 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
> put_device(dev);
> }
>
> +static int virtio_pci_sriov_configure(struct pci_dev *pci_dev, int num_vfs)
> +{
> + struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> + struct virtio_device *vdev = &vp_dev->vdev;
> + int ret;
> +
> + if (!(vdev->config->get_status(vdev) & VIRTIO_CONFIG_S_DRIVER_OK))
> + return -EBUSY;
> +
> + if (!__virtio_test_bit(vdev, VIRTIO_F_SR_IOV))
> + return -EINVAL;
> +
> + if (pci_vfs_assigned(pci_dev))
> + return -EPERM;
Not a comment on this patch - existing code has the
same race - but generally
1. this seems racy since assigning vfs does not seem
to take device lock
2. does this work correctly for kvm at all?
pci_set_dev_assigned seems to be only called by xen.
Can you look at addressing this pls?
> +
> + if (num_vfs == 0) {
> + pci_disable_sriov(pci_dev);
> + return 0;
> + }
> +
> + ret = pci_enable_sriov(pci_dev, num_vfs);
> + if (ret < 0)
> + return ret;
> +
> + return num_vfs;
> +}
> +
> static struct pci_driver virtio_pci_driver = {
> .name = "virtio-pci",
> .id_table = virtio_pci_id_table,
> @@ -596,6 +625,7 @@ static struct pci_driver virtio_pci_driver = {
> #ifdef CONFIG_PM_SLEEP
> .driver.pm = &virtio_pci_pm_ops,
> #endif
> + .sriov_configure = virtio_pci_sriov_configure,
> };
>
> module_pci_driver(virtio_pci_driver);
> diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> index 2555d80f6eec..07571daccfec 100644
> --- a/drivers/virtio/virtio_pci_modern.c
> +++ b/drivers/virtio/virtio_pci_modern.c
> @@ -153,14 +153,28 @@ static u64 vp_get_features(struct virtio_device *vdev)
> return features;
> }
>
> +static void vp_transport_features(struct virtio_device *vdev, u64 features)
> +{
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + struct pci_dev *pci_dev = vp_dev->pci_dev;
> +
> + if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
> + pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
> + __virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
> +}
> +
> /* virtio config->finalize_features() implementation */
> static int vp_finalize_features(struct virtio_device *vdev)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + u64 features = vdev->features;
>
> /* Give virtio_ring a chance to accept features. */
> vring_transport_features(vdev);
>
> + /* Give virtio_pci a chance to accept features. */
> + vp_transport_features(vdev, features);
> +
> if (!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
> dev_err(&vdev->dev, "virtio: device uses modern interface "
> "but does not have VIRTIO_F_VERSION_1\n");
> diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> index 308e2096291f..b7c1f4e7d59e 100644
> --- a/include/uapi/linux/virtio_config.h
> +++ b/include/uapi/linux/virtio_config.h
> @@ -49,7 +49,7 @@
> * transport being used (eg. virtio_ring), the rest are per-device feature
> * bits. */
> #define VIRTIO_TRANSPORT_F_START 28
> -#define VIRTIO_TRANSPORT_F_END 34
> +#define VIRTIO_TRANSPORT_F_END 38
>
> #ifndef VIRTIO_CONFIG_NO_LEGACY
> /* Do we get callbacks when the ring is completely used, even if we've
> @@ -71,4 +71,9 @@
> * this is for compatibility with legacy systems.
> */
> #define VIRTIO_F_IOMMU_PLATFORM 33
> +
> +/*
> + * Does the device support Single Root I/O Virtualization?
> + */
> +#define VIRTIO_F_SR_IOV 37
> #endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
> --
> 2.17.0
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