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

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Message-ID: <0451e362-30eb-2ba2-33f1-e9ab3972cada@gmail.com>
Date:   Sun, 27 Sep 2020 00:24:54 +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:
...
> +	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;

I guess the idea of this patch is to print out the hardware state, isn't
it? Hence the as->count shouldn't be checked here.

> +		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);
> +
> +		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);
>

Would be nice if you could improve the output formatting by printing out
contiguous ranges that have the same ATTRs, otherwise it could be a bit
too large and unpractical output in a case if lots of pages are mapped.