lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <20220727015626-mutt-send-email-mst@kernel.org> Date: Wed, 27 Jul 2022 02:01:17 -0400 From: "Michael S. Tsirkin" <mst@...hat.com> To: Parav Pandit <parav@...dia.com> Cc: "Zhu, Lingshan" <lingshan.zhu@...el.com>, "jasowang@...hat.com" <jasowang@...hat.com>, "virtualization@...ts.linux-foundation.org" <virtualization@...ts.linux-foundation.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "xieyongji@...edance.com" <xieyongji@...edance.com>, "gautam.dawar@....com" <gautam.dawar@....com> Subject: Re: [PATCH V3 5/6] vDPA: answer num of queue pairs = 1 to userspace when VIRTIO_NET_F_MQ == 0 On Wed, Jul 27, 2022 at 03:47:35AM +0000, Parav Pandit wrote: > > > From: Zhu, Lingshan <lingshan.zhu@...el.com> > > Sent: Tuesday, July 26, 2022 10:53 PM > > > > On 7/27/2022 10:17 AM, Parav Pandit wrote: > > >> From: Zhu, Lingshan <lingshan.zhu@...el.com> > > >> Sent: Tuesday, July 26, 2022 10:15 PM > > >> > > >> On 7/26/2022 11:56 PM, Parav Pandit wrote: > > >>>> From: Zhu, Lingshan <lingshan.zhu@...el.com> > > >>>> Sent: Tuesday, July 12, 2022 11:46 PM > > >>>>> When the user space which invokes netlink commands, detects that > > >> _MQ > > >>>> is not supported, hence it takes max_queue_pair = 1 by itself. > > >>>> I think the kernel module have all necessary information and it is > > >>>> the only one which have precise information of a device, so it > > >>>> should answer precisely than let the user space guess. The kernel > > >>>> module should be reliable than stay silent, leave the question to > > >>>> the user space > > >> tool. > > >>> Kernel is reliable. It doesn’t expose a config space field if the > > >>> field doesn’t > > >> exist regardless of field should have default or no default. > > >> so when you know it is one queue pair, you should answer one, not try > > >> to guess. > > >>> User space should not guess either. User space gets to see if _MQ > > >> present/not present. If _MQ present than get reliable data from kernel. > > >>> If _MQ not present, it means this device has one VQ pair. > > >> it is still a guess, right? And all user space tools implemented this > > >> feature need to guess > > > No. it is not a guess. > > > It is explicitly checking the _MQ feature and deriving the value. > > > The code you proposed will be present in the user space. > > > It will be uniform for _MQ and 10 other features that are present now and > > in the future. > > MQ and other features like RSS are different. If there is no _RSS_XX, there > > are no attributes like max_rss_key_size, and there is not a default value. > > But for MQ, we know it has to be 1 wihtout _MQ. > "we" = user space. > To keep the consistency among all the config space fields. Actually I looked and the code some more and I'm puzzled: struct virtio_net_config config = {}; u64 features; u16 val_u16; vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config)); if (nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR, sizeof(config.mac), config.mac)) return -EMSGSIZE; Mac returned even without VIRTIO_NET_F_MAC val_u16 = le16_to_cpu(config.status); if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_STATUS, val_u16)) return -EMSGSIZE; status returned even without VIRTIO_NET_F_STATUS val_u16 = le16_to_cpu(config.mtu); if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16)) return -EMSGSIZE; MTU returned even without VIRTIO_NET_F_MTU What's going on here? -- MST
Powered by blists - more mailing lists