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From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Joerg Roedel <joro@8bytes.org>,
        David Woodhouse <dwmw2@infradead.org>,
        "Alex Williamson" <alex.williamson@redhat.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>
CC:     "Liu, Yi L" <yi.l.liu@intel.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        Christoph Hellwig <hch@infradead.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Eric Auger <eric.auger@redhat.com>
Subject: RE: [PATCH V10 04/11] iommu/vt-d: Use helper function to skip agaw
 for SL
Thread-Topic: [PATCH V10 04/11] iommu/vt-d: Use helper function to skip agaw
 for SL
Thread-Index: AQHV/w5fSzCgga8qmUGqovU+x6tW2KhcXtQQ
Date:   Fri, 27 Mar 2020 11:55:09 +0000
Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D19D7ED91C@SHSMSX104.ccr.corp.intel.com>
References: <1584746861-76386-1-git-send-email-jacob.jun.pan@linux.intel.com>
 <1584746861-76386-5-git-send-email-jacob.jun.pan@linux.intel.com>
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> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Sent: Saturday, March 21, 2020 7:28 AM
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
>  drivers/iommu/intel-pasid.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index 191508c7c03e..9bdb7ee228b6 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -544,17 +544,11 @@ int intel_pasid_setup_second_level(struct
> intel_iommu *iommu,
>  		return -EINVAL;
>  	}
> 
> -	/*
> -	 * Skip top levels of page tables for iommu which has less agaw
> -	 * than default. Unnecessary for PT mode.
> -	 */
>  	pgd = domain->pgd;
> -	for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) {
> -		pgd = phys_to_virt(dma_pte_addr(pgd));
> -		if (!dma_pte_present(pgd)) {
> -			dev_err(dev, "Invalid domain page table\n");
> -			return -EINVAL;
> -		}
> +	agaw = iommu_skip_agaw(domain, iommu, &pgd);
> +	if (agaw < 0) {
> +		dev_err(dev, "Invalid domain page table\n");
> +		return -EINVAL;
>  	}

ok, I see how it is used. possibly combine last and this one together since
it's mostly moving code...

> 
>  	pgd_val = virt_to_phys(pgd);
> --
> 2.7.4