RE: [PATCH v2 19/21] wifi: rtl8xxxu: add hw crypto support for AP mode

[Ping-Ke Shih <pkshih@realtek.com>]

> -----Original Message-----
> From: Martin Kaistra <martin.kaistra@linutronix.de>
> Sent: Monday, January 15, 2024 9:13 PM
> To: Ping-Ke Shih <pkshih@realtek.com>; linux-wireless@vger.kernel.org
> Cc: Jes Sorensen <Jes.Sorensen@gmail.com>; Kalle Valo <kvalo@kernel.org>; Bitterblue Smith
> <rtl8821cerfe2@gmail.com>; Sebastian Andrzej Siewior <bigeasy@linutronix.de>; Zenm Chen
> <zenmchen@gmail.com>
> Subject: Re: [PATCH v2 19/21] wifi: rtl8xxxu: add hw crypto support for AP mode
> 
> Hi Ping-Ke,
> 
> Am 12.01.24 um 07:52 schrieb Ping-Ke Shih:
> > Hi Martin,
> >
> >> -----Original Message-----
> >> From: Martin Kaistra <martin.kaistra@linutronix.de>
> >> Sent: Friday, December 22, 2023 12:44 AM
> >> To: linux-wireless@vger.kernel.org
> >> Cc: Jes Sorensen <Jes.Sorensen@gmail.com>; Kalle Valo <kvalo@kernel.org>; Ping-Ke Shih
> >> <pkshih@realtek.com>; Bitterblue Smith <rtl8821cerfe2@gmail.com>; Sebastian Andrzej Siewior
> >> <bigeasy@linutronix.de>
> >> Subject: [PATCH v2 19/21] wifi: rtl8xxxu: add hw crypto support for AP mode
> >>
> >
> > [...]
> >
> > Zenm reported [1] his RTL8192EU and RTL8192FU don't work in station mode,
> > and cause is this patch. Please try if you can reproduce the symptom, and
> > apply my suggestion to see if help.
> >
> > [1]
> https://lore.kernel.org/linux-wireless/20240112045104.12282-1-zenmchen@gmail.com/T/#me0940f522249becf4
> 9f25bc281f1992c523673f6
> 
> I managed to find two other Realtek USB Wifi devices that are supported by the
> rtl8xxxu driver (RTL8188EU and RTL8192CU) and I can reproduce the issue with
> both of them.
> 
> I also tried creating a patch with your suggestions and this seems to help.
> 
> Looking at it more closely however, I think the main problem is, that
> fops->max_sec_cam_num is not set for the other variants. Without the additional
> patch, this causes rtl8xxxu_get_free_sec_cam() to return 0 for pairwise and
> group key and so using the same spot for both key entries.
> 
> I then created a patch using the numbers suggested by Bitterblue Smith in [1]
> and using 32 for RTL8723AU and RTL8192CU like the rtlwifi driver seems to do.
> This also seems to solve the issue reported, even without reserving the first 4
> slots for group keys.
> 
> Do you think we need both patches?

I think you only need the one that fills fops->max_sec_cam_num.

The search rule of hardware security CAM is to find an entry that matches address
and key_idx, and then use it to encrypt/decrypt packets. If no entry found, it
select entry by key_idx (i.e. key_idx=0/1/2/3 use entry=0/1/2/3). As I can
remember, WEP needs to reserve 4 entries, but I believe no one uses it now.

> 
> [1]
> https://lore.kernel.org/linux-wireless/f73b5afc-d69f-4a7c-8bf0-877a45327e0b@gmail.com/
> 
> >>          case DISABLE_KEY:
> >>                  rtl8xxxu_write32(priv, REG_CAM_WRITE, 0x00000000);
> >>                  val32 = CAM_CMD_POLLING | CAM_CMD_WRITE |
> >> -                       key->keyidx << CAM_CMD_KEY_SHIFT;
> >> +                       key->hw_key_idx << CAM_CMD_KEY_SHIFT;
> >>                  rtl8xxxu_write32(priv, REG_CAM_CMD, val32);
> >> +               rtlvif->hw_key_idx = 0xff;
> >> +               clear_bit(key->hw_key_idx, priv->cam_map);
> >
> > Shouldn't swap these two statements? I missed that during reviewing.
> 
> I don't think that would make a difference. rtlvif->hw_key_idx is set for use in
> rtl8xxxu_tx() and the second line uses key->hw_key_idx to clear the map entry.
> 

Sorry, I misread the "rtlvif->..." and "key->..." that are different.