linux-kernel - Re: [PATCH 4/4] hv_netvsc: Restrict configurations on isolated guests

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Date:   Thu, 21 Jan 2021 17:53:45 +0100
From:   Andrea Parri <parri.andrea@...il.com>
To:     Haiyang Zhang <haiyangz@...rosoft.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        Michael Kelley <mikelley@...rosoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        Saruhan Karademir <skarade@...rosoft.com>,
        Juan Vazquez <juvazq@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 4/4] hv_netvsc: Restrict configurations on isolated guests

> > > > @@ -544,7 +545,8 @@ static int negotiate_nvsp_ver(struct hv_device
> > > > *device,
> > > >  	init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1;
> > > >
> > > >  	if (nvsp_ver >= NVSP_PROTOCOL_VERSION_5) {
> > > > -		init_packet->msg.v2_msg.send_ndis_config.capability.sriov =
> > > > 1;
> > > > +		if (!hv_is_isolation_supported())
> > > > +			init_packet-
> > > > >msg.v2_msg.send_ndis_config.capability.sriov = 1;
> > >
> > > Please also add a log there stating we don't support sriov in this case.
> > Otherwise,
> > > customers will ask why vf not showing up.
> > 
> > IIUC, you're suggesting that I append something like:
> > 
> > +		else
> > +			netdev_info(ndev, "SR-IOV not advertised: isolation
> > supported\n");
> > 
> > I've added this locally; please let me know if you had something else
> > /better in mind.
> 
> This message explains the failure reason better:
>   "SR-IOV not advertised by guests on the host supporting isolation"

Applied.


> > > > @@ -579,12 +588,17 @@ static int netvsc_connect_vsp(struct hv_device
> > > > *device,
> > > >  	init_packet = &net_device->channel_init_pkt;
> > > >
> > > >  	/* Negotiate the latest NVSP protocol supported */
> > > > -	for (i = ARRAY_SIZE(ver_list) - 1; i >= 0; i--)
> > > > +	for (i = ARRAY_SIZE(ver_list) - 1; i >= 0; i--) {
> > > > +		if (!nvsp_is_valid_version(ver_list[i])) {
> > > > +			ret = -EPROTO;
> > > > +			goto cleanup;
> > > > +		}
> > >
> > > This code can catch the invalid, but cannot get the current host nvsp
> > version.
> > > I'd suggest move this check after version negotiation is done. So we can log
> > what's
> > > the current host nvsp version, and why we fail it (the expected nvsp ver).
> > 
> > Mmh, invalid versions are not negotiated.  How about I simply add the
> > following logging right before the above 'ret = -EPROTO' say?
> > 
> > +			netdev_err(ndev, "Invalid NVSP version %x
> > (expected >= %x): isolation supported\n",
> > +				   ver_list[i], NVSP_PROTOCOL_VERSION_61);
> > 
> > (or something along these lines)
> 
> The negotiation process runs from the latest to oldest. If the host is 5, your code 
> will fail before trying v6.0, and log:
> 	"Invalid NVSP version 60000  (expected >= 60001): isolation supported"
> This will make user think the NVSP version is 6.0.
> 
> Since you will let the NIC fail and cleanup, there is no harm to check the version 
> after negotiation. And this case is unexpected from a "normal" host. So I suggest 
> move the check after negotiation is done, then we know the actual host nvsp 
> version that causing this issue. And we can bring the accurate info to host team 
> for better diagnosability.

Fair enough, will do.


> Please point out this invalid version is caused by the host side, like this:
> 	"Invalid NVSP version 0x50000  (expected >= 0x60001) from the host with isolation support"
> Also please use "0x%x" for hexadecimal numbers.

Sure.


> > > > @@ -1357,7 +1371,8 @@ static void netvsc_receive_inband(struct
> > > > net_device *ndev,
> > > >  		break;
> > > >
> > > >  	case NVSP_MSG4_TYPE_SEND_VF_ASSOCIATION:
> > > > -		netvsc_send_vf(ndev, nvmsg, msglen);
> > > > +		if (!hv_is_isolation_supported())
> > > > +			netvsc_send_vf(ndev, nvmsg, msglen);
> > >
> > > When the driver doesn't advertise SRIOV, this message is not expected.
> > > Instead of ignore silently, we should log an error.
> > 
> > I've appended:
> > 
> > +		else
> > +			netdev_err(ndev, "Unexpected VF message:
> > isolation supported\n");
> 
> Please log the msg type:
>   "Ignore VF_ASSOCIATION msg from the host supporting isolation"

Applied.

Thanks,
  Andrea