linux-kernel - Re: [PATCH v2] igb: Allocate MSI-X vector when testing

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Message-ID: <Y3z4SlmtA/u/3ipA@boxer>
Date:   Tue, 22 Nov 2022 17:26:50 +0100
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     Akihiko Odaki <akihiko.odaki@...nix.com>
CC:     <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <intel-wired-lan@...ts.osuosl.org>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "Yan Vugenfirer" <yan@...nix.com>,
        Yuri Benditovich <yuri.benditovich@...nix.com>
Subject: Re: [PATCH v2] igb: Allocate MSI-X vector when testing

On Tue, Nov 22, 2022 at 10:11:45PM +0900, Akihiko Odaki wrote:
> Without this change, the interrupt test fail with MSI-X environment:
> 
> $ sudo ethtool -t enp0s2 offline
> [   43.921783] igb 0000:00:02.0: offline testing starting
> [   44.855824] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Down
> [   44.961249] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
> [   51.272202] igb 0000:00:02.0: testing shared interrupt
> [   56.996975] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
> The test result is FAIL
> The test extra info:
> Register test  (offline)	 0
> Eeprom test    (offline)	 0
> Interrupt test (offline)	 4
> Loopback test  (offline)	 0
> Link test   (on/offline)	 0
> 
> Here, "4" means an expected interrupt was not delivered.
> 
> This change routes interrupts correctly to the first MSI-X vector, and
> fixes the test:

Try to use imperative mood - simply stating something like "To fix this,
route IRQs correctly to the first MSI-X vector by xyz"

> 
> $ sudo ethtool -t enp0s2 offline
> [   42.762985] igb 0000:00:02.0: offline testing starting
> [   50.141967] igb 0000:00:02.0: testing shared interrupt
> [   56.163957] igb 0000:00:02.0 enp0s2: igb: enp0s2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
> The test result is PASS
> The test extra info:
> Register test  (offline)	 0
> Eeprom test    (offline)	 0
> Interrupt test (offline)	 0
> Loopback test  (offline)	 0
> Link test   (on/offline)	 0

Looks better now, would be also good to explain what is the *actual* fix
by explaining the HW registers setting that you're doing.

Thanks!

> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@...nix.com>
> ---
>  drivers/net/ethernet/intel/igb/igb_ethtool.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
> index e5f3e7680dc6..ff911af16a4b 100644
> --- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
> +++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
> @@ -1413,6 +1413,8 @@ static int igb_intr_test(struct igb_adapter *adapter, u64 *data)
>  			*data = 1;
>  			return -1;
>  		}
> +		wr32(E1000_IVAR_MISC, E1000_IVAR_VALID << 8);
> +		wr32(E1000_EIMS, BIT(0));
>  	} else if (adapter->flags & IGB_FLAG_HAS_MSI) {
>  		shared_int = false;
>  		if (request_irq(irq,
> -- 
> 2.38.1
>