linux-kernel - Re: [PATCH 5/5] iommu/tegra-smmu: Add pagetable mappings to debugfs

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Message-ID: <0c9ca297-d656-59a5-eefd-00e0c0542c29@gmail.com>
Date:   Sat, 26 Sep 2020 17:48:54 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Nicolin Chen <nicoleotsuka@...il.com>, thierry.reding@...il.com,
        joro@...tes.org, krzk@...nel.org
Cc:     linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, jonathanh@...dia.com
Subject: Re: [PATCH 5/5] iommu/tegra-smmu: Add pagetable mappings to debugfs

26.09.2020 11:07, Nicolin Chen пишет:
...
> +static int tegra_smmu_mappings_show(struct seq_file *s, void *data)
> +{
> +	struct tegra_smmu_group_debug *group_debug = s->private;
> +	const struct tegra_smmu_swgroup *group;
> +	struct tegra_smmu_as *as;
> +	struct tegra_smmu *smmu;
> +	int pd_index, pt_index;
> +	u64 pte_count = 0;
> +	u32 pde_count = 0;
> +	u32 val, ptb_reg;
> +	u32 *pd;
> +
> +	if (!group_debug || !group_debug->priv || !group_debug->group)
> +		return 0;
> +
> +	group = group_debug->group;
> +	as = group_debug->priv;
> +	smmu = as->smmu;
> +
> +	val = smmu_readl(smmu, group->reg) & SMMU_ASID_ENABLE;
> +	if (!val)
> +		return 0;
> +
> +	pd = page_address(as->pd);
> +	if (!pd)
> +		return 0;
> +
> +	seq_printf(s, "\nSWGROUP: %s\nASID: %d\nreg: 0x%x\n", group->name,
> +			as->id, group->reg);
> +
> +	mutex_lock(&smmu->lock);
> +	smmu_writel(smmu, as->id & 0x7f, SMMU_PTB_ASID);
> +	ptb_reg = smmu_readl(smmu, SMMU_PTB_DATA);

I think the whole traverse needs a locking protection, doesn't it?

> +	mutex_unlock(&smmu->lock);
> +
> +	seq_printf(s, "PTB_ASID: 0x%x\nas->pd_dma: 0x%llx\n", ptb_reg, as->pd_dma);
> +	seq_puts(s, "{\n");
> +
> +	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.

> +		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);
> +		}
> +		seq_puts(s, "\t}\n");
> +	}
> +	seq_puts(s, "}\n");
> +	seq_printf(s, "Total PDE count: %d\n", pde_count);
> +	seq_printf(s, "Total PTE count: %lld\n", pte_count);
> +
> +	return 0;
> +}
> +
> +DEFINE_SHOW_ATTRIBUTE(tegra_smmu_mappings);
> +
>  static void tegra_smmu_debugfs_init(struct tegra_smmu *smmu)
>  {
> +	const struct tegra_smmu_soc *soc = smmu->soc;
> +	struct tegra_smmu_group_debug *group_debug;
> +	struct device *dev = smmu->dev;
> +	struct dentry *d;
> +	int i;
> +
> +	group_debug = devm_kzalloc(dev, sizeof(*group_debug) * soc->num_swgroups, GFP_KERNEL);

devm_kcalloc()