linux-kernel - RE: [PATCH v9 07/10] iommu/vt-d: Allow qi_submit

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Message-ID: <BN9PR11MB52768F21FE29A81060ACA4AE8C9DA@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Fri, 29 Dec 2023 02:52:45 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: "Liu, Yi L" <yi.l.liu@...el.com>, "joro@...tes.org" <joro@...tes.org>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>, "jgg@...dia.com"
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	"baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>
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 Zhenzhong" <zhenzhong.duan@...el.com>, "joao.m.martins@...cle.com"
	<joao.m.martins@...cle.com>, "Zeng, Xin" <xin.zeng@...el.com>, "Zhao, Yan Y"
	<yan.y.zhao@...el.com>, "j.granados@...sung.com" <j.granados@...sung.com>
Subject: RE: [PATCH v9 07/10] iommu/vt-d: Allow qi_submit_sync() to return the
 QI faults

> From: Liu, Yi L <yi.l.liu@...el.com>
> Sent: Thursday, December 28, 2023 11:06 PM
> 
> From: Lu Baolu <baolu.lu@...ux.intel.com>
> 
> This allows qi_submit_sync() to return back faults to callers.

this might be useful to add a note that the retry logic itself is being discussed
in a separate thread [1]. Here we keep it intact and just make sure no retry for
the newly added user domain cache invalidation.

[1] https://lore.kernel.org/all/20231228001646.587653-6-haifeng.zhao@linux.intel.com/

> 
> -		if (qi->desc_status[wait_index] == QI_ABORT)
> +		if (qi->desc_status[wait_index] == QI_ABORT) {
> +			/*
> +			 * If the caller is interested in the error, no need
> +			 * to retry, just return the time out error to the
> +			 * caller.
> +			 */
> +			if (fsts)
> +				return -ETIMEDOUT;
> +		}
>  			return -EAGAIN;

indent should be adjusted and it changes the original logic which returns
-EAGAIN only if QI_ABORT is set for the wait_index.

the simpler form is:

		/* No need to retry if the caller is interested in the timeout error */
		if (qi->desc_status[wait_index] == QI_ABORT)
			return fsts ? -ETIMEDOUT : -EAGAIN;

otherwise,

Reviewed-by: Kevin Tian <kevin.tian@...el.com>