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Date:   Wed, 28 Oct 2020 10:13:56 +0100
From:   Jean-Philippe Brucker <jean-philippe@linaro.org>
To:     Yi Sun <yi.y.sun@linux.intel.com>
Cc:     joro@8bytes.org, dwmw2@infradead.org, baolu.lu@linux.intel.com,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 2/3] iommu: Fix an issue in iommu_page_response()
 flags check
Message-ID: <20201028091356.GB2328726@myrica>
References: <1603849018-6578-1-git-send-email-yi.y.sun@linux.intel.com>
 <1603849018-6578-3-git-send-email-yi.y.sun@linux.intel.com>
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In-Reply-To: <1603849018-6578-3-git-send-email-yi.y.sun@linux.intel.com>
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Hi,

On Wed, Oct 28, 2020 at 09:36:57AM +0800, Yi Sun wrote:
> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> 
> original code fails when LAST_PAGE is set in flags.

LAST_PAGE is not documented to be a valid flags for page_response.
So isn't failing the right thing to do?

> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> ---
>  drivers/iommu/iommu.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 8c470f4..053cec3 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1200,9 +1200,11 @@ int iommu_page_response(struct device *dev,
>  		return -EINVAL;
>  
>  	if (msg->version != IOMMU_PAGE_RESP_VERSION_1 ||
> -	    msg->flags & ~IOMMU_PAGE_RESP_PASID_VALID)
> +		!(msg->flags & IOMMU_PAGE_RESP_PASID_VALID)) {

It should be OK not to have PASID_VALID set, we're just checking for
undefined flags here.

Thanks,
Jean

> +		dev_warn_ratelimited(dev, "%s:Invalid ver %x: flags %x\n",
> +				__func__, msg->version, msg->flags);
>  		return -EINVAL;
> -
> +	}
>  	/* Only send response if there is a fault report pending */
>  	mutex_lock(&param->fault_param->lock);
>  	if (list_empty(&param->fault_param->faults)) {
> -- 
> 2.7.4
> 
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