linux-kernel - Re: [PATCH net-next v7 4/5] net: rnpgbe: Add basic mbx

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: <8989E7A85A9468B0+20250825013053.GA2006401@nic-Precision-5820-Tower>
Date: Mon, 25 Aug 2025 09:30:53 +0800
From: Yibo Dong <dong100@...se.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
	corbet@....net, gur.stavi@...wei.com, maddy@...ux.ibm.com,
	mpe@...erman.id.au, danishanwar@...com, lee@...ger.us,
	gongfan1@...wei.com, lorenzo@...nel.org, geert+renesas@...der.be,
	Parthiban.Veerasooran@...rochip.com, lukas.bulwahn@...hat.com,
	alexanderduyck@...com, richardcochran@...il.com, kees@...nel.org,
	gustavoars@...nel.org, netdev@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH net-next v7 4/5] net: rnpgbe: Add basic mbx_fw support

On Sun, Aug 24, 2025 at 05:15:25PM +0200, Andrew Lunn wrote:
> On Sun, Aug 24, 2025 at 12:10:52PM +0800, Yibo Dong wrote:
> > On Sat, Aug 23, 2025 at 05:17:45PM +0200, Andrew Lunn wrote:
> > > On Sat, Aug 23, 2025 at 09:58:24AM +0800, Yibo Dong wrote:
> > > > On Fri, Aug 22, 2025 at 04:43:16PM +0200, Andrew Lunn wrote:
> > > > > > +/**
> > > > > > + * mucse_mbx_get_capability - Get hw abilities from fw
> > > > > > + * @hw: pointer to the HW structure
> > > > > > + *
> > > > > > + * mucse_mbx_get_capability tries to get capabities from
> > > > > > + * hw. Many retrys will do if it is failed.
> > > > > > + *
> > > > > > + * @return: 0 on success, negative on failure
> > > > > > + **/
> > > > > > +int mucse_mbx_get_capability(struct mucse_hw *hw)
> > > > > > +{
> > > > > > +	struct hw_abilities ability = {};
> > > > > > +	int try_cnt = 3;
> > > > > > +	int err = -EIO;
> > > > > > +
> > > > > > +	while (try_cnt--) {
> > > > > > +		err = mucse_fw_get_capability(hw, &ability);
> > > > > > +		if (err)
> > > > > > +			continue;
> > > > > > +		hw->pfvfnum = le16_to_cpu(ability.pfnum) & GENMASK_U16(7, 0);
> > > > > > +		return 0;
> > > > > > +	}
> > > > > > +	return err;
> > > > > > +}
> > > > > 
> > > > > Please could you add an explanation why it would fail? Is this to do
> > > > > with getting the driver and firmware in sync? Maybe you should make
> > > > > this explicit, add a function mucse_mbx_sync() with a comment that
> > > > > this is used once during probe to synchronise communication with the
> > > > > firmware. You can then remove this loop here.
> > > > 
> > > > It is just get some fw capability(or info such as fw version).
> > > > It is failed maybe:
> > > > 1. -EIO: return by mucse_obtain_mbx_lock_pf. The function tries to get
> > > > pf-fw lock(in chip register, not driver), failed when fw hold the lock.
> > > 
> > > If it cannot get the lock, isn't that fatal? You cannot do anything
> > > without the lock.
> > > 
> > > > 2. -ETIMEDOUT: return by mucse_poll_for_xx. Failed when timeout.
> > > > 3. -ETIMEDOUT: return by mucse_fw_send_cmd_wait. Failed when wait
> > > > response timeout.
> > > 
> > > If its dead, its dead. Why would it suddenly start responding?
> > > 
> > > > 4. -EIO: return by mucse_fw_send_cmd_wait. Failed when error_code in
> > > > response.
> > > 
> > > Which should be fatal. No retries necessary.
> > > 
> > > > 5. err return by mutex_lock_interruptible.
> > > 
> > > So you want the user to have to ^C three times?
> > > 
> > > And is mucse_mbx_get_capability() special, or will all interactions
> > > with the firmware have three retries?
> > 
> 
> > It is the first 'cmd with response' from fw when probe. If it failed,
> > return err and nothing else todo (no registe netdev ...). So, we design
> > to give retry for it.
> > fatal with no retry, maybe like this? 
>  
> Quoting myself:
> 
> > > > > Is this to do
> > > > > with getting the driver and firmware in sync? Maybe you should make
> > > > > this explicit, add a function mucse_mbx_sync() with a comment that
> > > > > this is used once during probe to synchronise communication with the
> > > > > firmware. You can then remove this loop here.

'mucse_mbx_get_capability' is used once during probe in fact, and won't be
used anywhere.

> 
> Does the firmware offer a NOP command? Or one to get the firmware
> version?  If you are trying to get the driver and firmware in sync, it
> make sense to use an operation which is low value and won't be used
> anywhere else.
> 
> 	Andrew
> 

No NOP command.. 'mucse_mbx_get_capability' can get the firmware version
and in fact only used in probe, maybe I should rename it to 'mucse_mbx_sync',
and add comment 'only be used once during probe'?
Or keep the name with that comment?

Thanks for your feedback.