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

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Date:   Sat, 26 Sep 2020 13:47:44 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     thierry.reding@...il.com, joro@...tes.org, krzk@...nel.org,
        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

Hi Dmitry,

Thank you for the review.

On Sat, Sep 26, 2020 at 05:48:54PM +0300, Dmitry Osipenko wrote:
> 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?

Hmm..probably would be nicer. Will move the mutex to the top.

> > +	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.

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);
> > +		}
> > +		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()

Will change it.

Thanks
Nic