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Subject: Re: [PATCH 5/5] iommu/tegra-smmu: Add pagetable mappings to debugfs
To:     Nicolin Chen <nicoleotsuka@gmail.com>
Cc:     thierry.reding@gmail.com, joro@8bytes.org, krzk@kernel.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
        iommu@lists.linux-foundation.org, jonathanh@nvidia.com
References: <20200926080719.6822-1-nicoleotsuka@gmail.com>
 <20200926080719.6822-6-nicoleotsuka@gmail.com>
 <0c9ca297-d656-59a5-eefd-00e0c0542c29@gmail.com>
 <20200926204744.GB4947@Asurada-Nvidia>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <fb0eec94-3a36-0e92-edf7-d8de0966a656@gmail.com>
Date:   Sun, 27 Sep 2020 00:41:51 +0300
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26.09.2020 23:47, Nicolin Chen пишет:
...
>>> +	for (pd_index = 0; pd_index < SMMU_NUM_PDE; pd_index++) {
>>> +		struct page *pt;
>>> +		u32 *addr;
>>> +
>>> +		if (!as->count[pd_index] || !pd[pd_index])
>>> +			continue;
>>> +
>>> +		pde_count++;
>>> +		pte_count += as->count[pd_index];
>>> +		seq_printf(s, "\t[%d] 0x%x (%d)\n",
>>> +			   pd_index, pd[pd_index], as->count[pd_index]);
>>> +		pt = as->pts[pd_index];
>>> +		addr = page_address(pt);
>>
>> This needs as->lock protection.
> 
> Will add that.
> 
>>> +		seq_puts(s, "\t{\n");
>>> +		seq_printf(s, "\t\t%-5s %-4s %12s %12s\n", "PDE", "ATTR", "PHYS", "IOVA");
>>> +		for (pt_index = 0; pt_index < SMMU_NUM_PTE; pt_index++) {
>>> +			u64 iova;
>>> +
>>> +			if (!addr[pt_index])
>>> +				continue;
>>> +
>>> +			iova = ((dma_addr_t)pd_index & (SMMU_NUM_PDE - 1)) << SMMU_PDE_SHIFT;
>>> +			iova |= ((dma_addr_t)pt_index & (SMMU_NUM_PTE - 1)) << SMMU_PTE_SHIFT;
>>> +
>>> +			seq_printf(s, "\t\t#%-4d 0x%-4x 0x%-12llx 0x%-12llx\n",
>>> +				   pt_index, addr[pt_index] >> SMMU_PTE_ATTR_SHIFT,
>>> +				   SMMU_PFN_PHYS(addr[pt_index] & ~SMMU_PTE_ATTR), iova);

Please also note that the addr[pt_index] needs to be protected as well.
Perhaps you could temporally bump the as->count.