From: Leon Romanovsky <leon@kernel.org>
To: Dexuan Cui <decui@microsoft.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
Wei Liu <liuwe@microsoft.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Subject: Re: [PATCH net-next] net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)
Date: Wed, 7 Apr 2021 15:51:18 +0300 [thread overview]
Message-ID: <YG2qxjPJ4ruas1dI@unreal> (raw)
In-Reply-To: <MW2PR2101MB08923D4417E44C5750BFB964BF759@MW2PR2101MB0892.namprd21.prod.outlook.com>
On Wed, Apr 07, 2021 at 08:40:13AM +0000, Dexuan Cui wrote:
> > From: Leon Romanovsky <leon@kernel.org>
> > Sent: Wednesday, April 7, 2021 1:10 AM
> >
> > <...>
> >
> > > +int gdma_verify_vf_version(struct pci_dev *pdev)
> > > +{
> > > + struct gdma_context *gc = pci_get_drvdata(pdev);
> > > + struct gdma_verify_ver_req req = { 0 };
> > > + struct gdma_verify_ver_resp resp = { 0 };
> > > + int err;
> > > +
> > > + gdma_init_req_hdr(&req.hdr, GDMA_VERIFY_VF_DRIVER_VERSION,
> > > + sizeof(req), sizeof(resp));
> > > +
> > > + req.protocol_ver_min = GDMA_PROTOCOL_FIRST;
> > > + req.protocol_ver_max = GDMA_PROTOCOL_LAST;
> > > +
> > > + err = gdma_send_request(gc, sizeof(req), &req, sizeof(resp), &resp);
> > > + if (err || resp.hdr.status) {
> > > + pr_err("VfVerifyVersionOutput: %d, status=0x%x\n", err,
> > > + resp.hdr.status);
> > > + return -EPROTO;
> > > + }
> > > +
> > > + return 0;
> > > +}
> >
> > <...>
> > > + err = gdma_verify_vf_version(pdev);
> > > + if (err)
> > > + goto remove_irq;
> >
> > Will this VF driver be used in the guest VM? What will prevent from users to
> > change it?
> > I think that such version negotiation scheme is not allowed.
>
> Yes, the VF driver is expected to run in a Linux VM that runs on Azure.
>
> Currently gdma_verify_vf_version() just tells the PF driver that the VF driver
> is only able to support GDMA_PROTOCOL_V1, and want to use
> GDMA_PROTOCOL_V1's message formats to talk to the PF driver later.
>
> enum {
> GDMA_PROTOCOL_UNDEFINED = 0,
> GDMA_PROTOCOL_V1 = 1,
> GDMA_PROTOCOL_FIRST = GDMA_PROTOCOL_V1,
> GDMA_PROTOCOL_LAST = GDMA_PROTOCOL_V1,
> GDMA_PROTOCOL_VALUE_MAX
> };
>
> The PF driver is supposed to always support GDMA_PROTOCOL_V1, so I expect
> here gdma_verify_vf_version() should succeed. If a user changes the Linux VF
> driver and try to use a protocol version not supported by the PF driver, then
> gdma_verify_vf_version() will fail; later, if the VF driver tries to talk to the PF
> driver using an unsupported message format, the PF driver will return a failure.
The worry is not for the current code, but for the future one when you will
support v2, v3 e.t.c. First, your code will look like a spaghetti and
second, users will try and mix vX with "unsupported" commands just for the
fun.
Thanks
>
> Thanks,
> -- Dexuan
next prev parent reply other threads:[~2021-04-07 12:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-06 23:23 [PATCH net-next] net: mana: Add a driver for Microsoft Azure Network Adapter (MANA) Dexuan Cui
2021-04-07 1:07 ` Andrew Lunn
2021-04-07 8:02 ` Dexuan Cui
2021-04-07 8:15 ` Leon Romanovsky
2021-04-07 8:28 ` Dexuan Cui
2021-04-07 12:44 ` Leon Romanovsky
2021-04-07 21:59 ` Dexuan Cui
2021-04-07 22:37 ` Bernd Petrovitsch
2021-04-08 7:30 ` Leon Romanovsky
2021-04-07 12:19 ` Andrew Lunn
2021-04-07 1:30 ` kernel test robot
2021-04-07 8:08 ` Dexuan Cui
2021-04-07 13:02 ` Wei Liu
2021-04-07 1:52 ` kernel test robot
2021-04-07 1:53 ` kernel test robot
2021-04-07 8:10 ` Leon Romanovsky
2021-04-07 8:40 ` Dexuan Cui
2021-04-07 12:51 ` Leon Romanovsky [this message]
2021-04-07 14:41 ` Haiyang Zhang
2021-04-07 14:55 ` Leon Romanovsky
2021-04-07 15:05 ` Haiyang Zhang
2021-04-07 17:07 ` Leon Romanovsky
2021-04-07 13:17 ` Wei Liu
2021-04-07 14:34 ` Haiyang Zhang
2021-04-07 15:00 ` Wei Liu
2021-04-07 15:16 ` Haiyang Zhang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YG2qxjPJ4ruas1dI@unreal \
--to=leon@kernel.org \
--cc=davem@davemloft.net \
--cc=decui@microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=kuba@kernel.org \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=liuwe@microsoft.com \
--cc=netdev@vger.kernel.org \
--cc=sthemmin@microsoft.com \
--cc=wei.liu@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).