On 9/26/2022 12:11 AM, Jason Wang
wrote:
Actually no, that is why I said the name is a bit confusing and "supported_features" might sound better. This attribute in the parent device (mgmtdev) denotes the real device capability for what virtio features can be supported by the parent device. Any unprivileged user can check into this field to know parent device's capability without having to create a child vDPA device at all. The features that child vDPA device may support should be a subset of, or at most up to what the parent device offers. For e.g. the vdpa device dev1 you created below can expose less or equal device_features bit than 0x308820028 (MTU MAC CTRL_VQ CTRL_MAC_ADDR ANY_LAYOUT VERSION_1 ACCESS_PLATFORM), but shouldn't be no more than what the parent device can actually support.On Sat, Sep 24, 2022 at 4:01 AM Si-Wei Liu <si-wei.liu@xxxxxxxxxx> wrote:On 9/21/2022 7:43 PM, Jason Wang wrote:This patch implements features provisioning for vdpa_sim_net. 1) validating the provisioned features to be a subset of the parent features. 2) clearing the features that is not wanted by the userspace For example: # vdpa mgmtdev show vdpasim_net: supported_classes net max_supported_vqs 3 dev_features MTU MAC CTRL_VQ CTRL_MAC_ADDR ANY_LAYOUT VERSION_1 ACCESS_PLATFORMSighs, not to blame any one and it's perhaps too late, but this "dev_features" attr in "mgmtdev show" command output should have been called "supported_features" in the first place.Not sure I get this, but I guess this is the negotiated features actually.
Does it imply this series is connected to another work in parallel? Is it possible to add a reference in the cover letter?I think Ling Shan is working on reporting both negotiated features with the device features.
Noted here the device_features argument specified during vdpa creation is introduced by this series itself, it somehow slightly changed the original semantics of what device_features used to be.1) provision vDPA device with all features that are supported by the net simulator # vdpa dev add name dev1 mgmtdev vdpasim_net # vdpa dev config show dev1: mac 00:00:00:00:00:00 link up link_announce false mtu 1500 negotiated_features MTU MAC CTRL_VQ CTRL_MAC_ADDR VERSION_1 ACCESS_PLATFORMMaybe not in this patch, but for completeness for the whole series, could we also add device_features to the output?Lingshan, could you please share your thoughts or patch on this?
Right, ANY_LAYOUT is a bad example. A good example might be that, I knew the parent mgmtdev on migration source node supports CTRL_MAC_ADDR, but I don't find it in negotiated_features. On the migration destination node, the parent device does support all features as the source offers, including CTRL_MAC_ADDR. What device features you would expect the mgmt software to create destination vdpa device with, if not otherwise requiring mgmt software to remember all the arguments on device creation?When simply look at the "vdpa dev config show" output, I cannot really tell the actual device_features that was used in vdpa creation. For e.g. there is a missing feature ANY_LAYOUT from negotiated_features compared with supported_features in mgmtdev, but the orchestration software couldn't tell if the vdpa device on destination host should be created with or without the ANY_LAYOUT feature.I think VERSION_1 implies ANY_LAYOUT.
SOURCE# vdpa mgmtdev show
vdpasim_net:
supported_classes net
max_supported_vqs 3
dev_features MTU MAC CTRL_VQ CTRL_MAC_ADDR ANY_LAYOUT VERSION_1 ACCESS_PLATFORM
SOURCE# vdpa dev config show
dev1: mac 00:00:00:00:00:00 link up link_announce false mtu 1500
negotiated_features MTU MAC CTRL_VQ VERSION_1 ACCESS_PLATFORM
DESTINATION# vdpa mgmtdev show
vdpasim_net:
supported_classes net
max_supported_vqs 3
dev_features MTU MAC CTRL_VQ CTRL_MAC_ADDR ANY_LAYOUT VERSION_1 ACCESS_PLATFORM
Yes, this is one way mgmt software may implement, but I am not sure if it's the only way. For e.g. for cpu flags, mgmt software can infer the guest cpus features in use from all qemu command line arguments and host cpu features/capability, which doesn't need to remember creation arguments and is easy to recover from failure without having to make the VM config persistent in data store. I thought it would be great if vdpa CLI design could offer the same.But it should be sufficient to use features_src & feature_dst in this case. Actually, it should work similar as to the cpu flags, the management software should introduce the concept of cluster which means the maximal set of common features is calculated and provisioned during device creation to allow migration among the nodes inside the cluster.
Thanks,
-Siwei
ThanksThanks, -Siwei2) provision vDPA device with a subset of the features # vdpa dev add name dev1 mgmtdev vdpasim_net device_features 0x300020000 # vdpa dev config show dev1: mac 00:00:00:00:00:00 link up link_announce false mtu 1500 negotiated_features CTRL_VQ VERSION_1 ACCESS_PLATFORM Reviewed-by: Eli Cohen <elic@xxxxxxxxxx> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> --- drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c index 886449e88502..a9ba02be378b 100644 --- a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c +++ b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c @@ -254,6 +254,14 @@ static int vdpasim_net_dev_add(struct vdpa_mgmt_dev *mdev, const char *name, dev_attr.work_fn = vdpasim_net_work; dev_attr.buffer_size = PAGE_SIZE; + if (config->mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES)) { + if (config->device_features & + ~dev_attr.supported_features) + return -EINVAL; + dev_attr.supported_features &= + config->device_features; + } + simdev = vdpasim_create(&dev_attr); if (IS_ERR(simdev)) return PTR_ERR(simdev); @@ -294,7 +302,8 @@ static struct vdpa_mgmt_dev mgmt_dev = { .id_table = id_table, .ops = &vdpasim_net_mgmtdev_ops, .config_attr_mask = (1 << VDPA_ATTR_DEV_NET_CFG_MACADDR | - 1 << VDPA_ATTR_DEV_NET_CFG_MTU), + 1 << VDPA_ATTR_DEV_NET_CFG_MTU | + 1 << VDPA_ATTR_DEV_FEATURES), .max_supported_vqs = VDPASIM_NET_VQ_NUM, .supported_features = VDPASIM_NET_FEATURES, };
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