Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
IronPort-SDR: bDHF7AK9mZYpouMDPv4hs/0Lm8sqN/o5Oy4bwt2aRbrxs4nE9F6F3g6pPGCx9E/lIQYn/URLYu
 l2Ca7yjDqvBg==
IronPort-SDR: hFmrBJo7Lw54DVGU1sjW1hTTNaRCgzAIqFjN2qN/JhxkRSfx9I9NRSzPJByrrcvg0NjHEQp+ca
 EQYXm41zyQ2g==
Date:   Mon, 30 Mar 2020 10:50:57 -0700
From:   Jacob Pan <jacob.jun.pan@linux.intel.com>
To:     Lu Baolu <baolu.lu@linux.intel.com>
Cc:     "Tian, Kevin" <kevin.tian@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>,
        "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>,
        jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH V10 03/11] iommu/vt-d: Add a helper function to skip
 agaw
Message-ID: <20200330105057.222c5928@jacob-builder>
In-Reply-To: <d17053c3-9a40-837a-dffa-57492cded028@linux.intel.com>
References: <1584746861-76386-1-git-send-email-jacob.jun.pan@linux.intel.com>
        <1584746861-76386-4-git-send-email-jacob.jun.pan@linux.intel.com>
        <AADFC41AFE54684AB9EE6CBC0274A5D19D7ED8FF@SHSMSX104.ccr.corp.intel.com>
        <d17053c3-9a40-837a-dffa-57492cded028@linux.intel.com>
Organization: OTC
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, 29 Mar 2020 15:20:55 +0800
Lu Baolu <baolu.lu@linux.intel.com> wrote:

> On 2020/3/27 19:53, Tian, Kevin wrote:
> >> 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>  
> > 
> > could you elaborate in which scenario this helper function is
> > required?  
> 
> I added below commit message:
> 
>      An Intel iommu domain uses 5-level page table by default. If the
>      iommu that the domain tries to attach supports less page levels,
>      the top level page tables should be skipped. Add a helper to do
>      this so that it could be used in other places.
> 
Thanks Baolu,
I will also add this to my v11, it might save you some time :)


> Best regards,
> baolu
> 
> >     
> >> ---
> >>   drivers/iommu/intel-pasid.c | 22 ++++++++++++++++++++++
> >>   1 file changed, 22 insertions(+)
> >>
> >> diff --git a/drivers/iommu/intel-pasid.c
> >> b/drivers/iommu/intel-pasid.c index 22b30f10b396..191508c7c03e
> >> 100644 --- a/drivers/iommu/intel-pasid.c
> >> +++ b/drivers/iommu/intel-pasid.c
> >> @@ -500,6 +500,28 @@ int intel_pasid_setup_first_level(struct
> >> intel_iommu *iommu,
> >>   }
> >>
> >>   /*
> >> + * Skip top levels of page tables for iommu which has less agaw
> >> + * than default. Unnecessary for PT mode.
> >> + */
> >> +static inline int iommu_skip_agaw(struct dmar_domain *domain,
> >> +				  struct intel_iommu *iommu,
> >> +				  struct dma_pte **pgd)
> >> +{
> >> +	int agaw;
> >> +
> >> +	for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) {
> >> +		*pgd = phys_to_virt(dma_pte_addr(*pgd));
> >> +		if (!dma_pte_present(*pgd)) {
> >> +			return -EINVAL;
> >> +		}
> >> +	}
> >> +	pr_debug_ratelimited("%s: pgd: %llx, agaw %d d_agaw %d\n",
> >> __func__, (u64)*pgd,
> >> +		iommu->agaw, domain->agaw);
> >> +
> >> +	return agaw;
> >> +}
> >> +
> >> +/*
> >>    * Set up the scalable mode pasid entry for second only
> >> translation type. */
> >>   int intel_pasid_setup_second_level(struct intel_iommu *iommu,
> >> --
> >> 2.7.4  
> >   

[Jacob Pan]