linux-kernel - Re: [PATCH v4 2/5] iommu/vt-d: Remove the pasid present check in prq_event

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Message-ID: <90c772ce-6d2d-4a1d-bfec-5a7813be43e4@intel.com>
Date: Mon, 28 Oct 2024 15:50:46 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: Joel Granados <joel.granados@...nel.org>, David Woodhouse
	<dwmw2@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel
	<joro@...tes.org>, Will Deacon <will@...nel.org>, Robin Murphy
	<robin.murphy@....com>, Jason Gunthorpe <jgg@...pe.ca>, Kevin Tian
	<kevin.tian@...el.com>, Klaus Jensen <its@...elevant.dk>
CC: <linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>, Klaus Jensen
	<k.jensen@...sung.com>
Subject: Re: [PATCH v4 2/5] iommu/vt-d: Remove the pasid present check in
 prq_event_thread

On 2024/10/16 05:08, Joel Granados wrote:
> From: Klaus Jensen <k.jensen@...sung.com>
> 
> PASID is not strictly needed when handling a PRQ event; remove the check
> for the pasid present bit in the request. This change was not included
> in the creation of prq.c to emphasize the change in capability checks
> when handing PRQ events.
> 
> Signed-off-by: Klaus Jensen <k.jensen@...sung.com>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> Signed-off-by: Joel Granados <joel.granados@...nel.org>

looks like the PRQ draining is missed for the PRI usage. When a pasid
entry is destroyed, it might need to add helper similar to the
intel_drain_pasid_prq() to drain PRQ for the non-pasid usage.

> ---
>   drivers/iommu/intel/prq.c | 12 +++---------
>   1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/iommu/intel/prq.c b/drivers/iommu/intel/prq.c
> index d4f18eb46475..3c50c848893f 100644
> --- a/drivers/iommu/intel/prq.c
> +++ b/drivers/iommu/intel/prq.c
> @@ -223,18 +223,12 @@ static irqreturn_t prq_event_thread(int irq, void *d)
>   		req = &iommu->prq[head / sizeof(*req)];
>   		address = (u64)req->addr << VTD_PAGE_SHIFT;
>   
> -		if (unlikely(!req->pasid_present)) {
> -			pr_err("IOMMU: %s: Page request without PASID\n",
> -			       iommu->name);
> -bad_req:
> -			handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
> -			goto prq_advance;
> -		}
> -
>   		if (unlikely(!is_canonical_address(address))) {
>   			pr_err("IOMMU: %s: Address is not canonical\n",
>   			       iommu->name);
> -			goto bad_req;
> +bad_req:
> +			handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
> +			goto prq_advance;
>   		}
>   
>   		if (unlikely(req->pm_req && (req->rd_req | req->wr_req))) {
> 

-- 
Regards,
Yi Liu