netdev - RE: [PATCH iwl-next v4 08/12] ice: Save and load RX Queue head

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BN9PR11MB5276DFED75FE8F9372B7A3CE8C8BA@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Thu, 7 Dec 2023 07:55:17 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: "Cao, Yahui" <yahui.cao@...el.com>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "Liu, Lingyu" <lingyu.liu@...el.com>, "Chittim,
 Madhu" <madhu.chittim@...el.com>, "Samudrala, Sridhar"
	<sridhar.samudrala@...el.com>, "alex.williamson@...hat.com"
	<alex.williamson@...hat.com>, "jgg@...dia.com" <jgg@...dia.com>,
	"yishaih@...dia.com" <yishaih@...dia.com>,
	"shameerali.kolothum.thodi@...wei.com"
	<shameerali.kolothum.thodi@...wei.com>, "brett.creeley@....com"
	<brett.creeley@....com>, "davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>
Subject: RE: [PATCH iwl-next v4 08/12] ice: Save and load RX Queue head

> From: Cao, Yahui <yahui.cao@...el.com>
> Sent: Tuesday, November 21, 2023 10:51 AM
>
> +
> +		/* Once RX Queue is enabled, network traffic may come in at
> any
> +		 * time. As a result, RX Queue head needs to be loaded
> before
> +		 * RX Queue is enabled.
> +		 * For simplicity and integration, overwrite RX head just after
> +		 * RX ring context is configured.
> +		 */
> +		if (msg_slot->opcode == VIRTCHNL_OP_CONFIG_VSI_QUEUES)
> {
> +			ret = ice_migration_load_rx_head(vf, devstate);
> +			if (ret) {
> +				dev_err(dev, "VF %d failed to load rx head\n",
> +					vf->vf_id);
> +				goto out_clear_replay;
> +			}
> +		}
> +

Don't we have the same problem here as for TX head restore that the
vfio migration protocol doesn't carry a way to tell whether the IOAS
associated with the device has been restored then allowing RX DMA
at this point might cause device error?

@Jason, is it a common gap applying to all devices which include a
receiving path from link? How is it handled in mlx migration
driver? 

I may overlook an important aspect here but if not I wonder whether
the migration driver should keep DMA disabled (at least for RX) even
when the device moves to RUNNING and then introduce an explicit
enable-DMA state which VMM can request after it restores the
relevant IOAS/HWPT...
with the device.