linux-kernel - Re: [PATCH 14/34] AMD IOMMU: clue initialization code together

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Date:	Wed, 9 Jul 2008 18:55:12 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Joerg Roedel <joerg.roedel@....com>
Cc:	tglx@...utronix.de, mingo@...hat.com, linux-kernel@...r.kernel.org,
	iommu@...ts.linux-foundation.org, bhavna.sarathy@....com,
	Sebastian.Biemueller@....com, robert.richter@....com,
	joro@...tes.org
Subject: Re: [PATCH 14/34] AMD IOMMU: clue initialization code together

On Thu, 26 Jun 2008 21:27:50 +0200 Joerg Roedel <joerg.roedel@....com> wrote:

> This patch puts the AMD IOMMU ACPI table parsing and hardware initialization
> functions together to the main intialization routine.
> 
> index 555fcc9..c792ddc 100644
> --- a/arch/x86/kernel/amd_iommu_init.c
> +++ b/arch/x86/kernel/amd_iommu_init.c
> @@ -643,3 +643,129 @@ static int __init init_memory_definitions(struct acpi_table_header *table)
>  	return 0;
>  }
>  
> +int __init amd_iommu_init(void)
> +{
> +	int i, ret = 0;
> +
> +
> +	if (amd_iommu_disable) {
> +		printk(KERN_INFO "AMD IOMMU disabled by kernel command line\n");
> +		return 0;
> +	}
> +
> +	/*
> +	 * First parse ACPI tables to find the largest Bus/Dev/Func
> +	 * we need to handle. Upon this information the shared data
> +	 * structures for the IOMMUs in the system will be allocated
> +	 */
> +	if (acpi_table_parse("IVRS", find_last_devid_acpi) != 0)
> +		return -ENODEV;
> +
> +	dev_table_size     = TBL_SIZE(DEV_TABLE_ENTRY_SIZE);
> +	alias_table_size   = TBL_SIZE(ALIAS_TABLE_ENTRY_SIZE);
> +	rlookup_table_size = TBL_SIZE(RLOOKUP_TABLE_ENTRY_SIZE);
> +
> +	ret = -ENOMEM;
> +
> +	/* Device table - directly used by all IOMMUs */
> +	amd_iommu_dev_table = (void *)__get_free_pages(GFP_KERNEL,
> +				      get_order(dev_table_size));

Is there a reason for using __get_free_pages() in this manner everywhere? 
kmalloc() or kzalloc() are unsuitable?

> +	if (amd_iommu_dev_table == NULL)
> +		goto out;
> +
> +	/*
> +	 * Alias table - map PCI Bus/Dev/Func to Bus/Dev/Func the
> +	 * IOMMU see for that device
> +	 */
> +	amd_iommu_alias_table = (void *)__get_free_pages(GFP_KERNEL,
> +			get_order(alias_table_size));
> +	if (amd_iommu_alias_table == NULL)
> +		goto free;
> +
> +	/* IOMMU rlookup table - find the IOMMU for a specific device */
> +	amd_iommu_rlookup_table = (void *)__get_free_pages(GFP_KERNEL,
> +			get_order(rlookup_table_size));
> +	if (amd_iommu_rlookup_table == NULL)
> +		goto free;
> +
> +	/*
> +	 * Protection Domain table - maps devices to protection domains
> +	 * This table has the same size as the rlookup_table
> +	 */
> +	amd_iommu_pd_table = (void *)__get_free_pages(GFP_KERNEL,
> +				     get_order(rlookup_table_size));
> +	if (amd_iommu_pd_table == NULL)
> +		goto free;
> +
> +	amd_iommu_pd_alloc_bitmap = (void *)__get_free_pages(GFP_KERNEL,
> +					    get_order(MAX_DOMAIN_ID/8));
> +	if (amd_iommu_pd_alloc_bitmap == NULL)
> +		goto free;
> +
> +	/*
> +	 * memory is allocated now; initialize the device table with all zeroes
> +	 * and let all alias entries point to itself
> +	 */
> +	memset(amd_iommu_dev_table, 0, dev_table_size);
> +	for (i = 0; i < amd_iommu_last_bdf; ++i)
> +		amd_iommu_alias_table[i] = i;
> +
> +	memset(amd_iommu_pd_table, 0, rlookup_table_size);
> +	memset(amd_iommu_pd_alloc_bitmap, 0, MAX_DOMAIN_ID / 8);

Use of __GFP_ZERO in here would relieve us of a lot of memsets.

> +	/*
> +	 * never allocate domain 0 because its used as the non-allocated and
> +	 * error value placeholder
> +	 */
> +	amd_iommu_pd_alloc_bitmap[0] = 1;
> +
> +	/*
> +	 * now the data structures are allocated and basically initialized
> +	 * start the real acpi table scan
> +	 */
> +	ret = -ENODEV;
> +	if (acpi_table_parse("IVRS", init_iommu_all) != 0)
> +		goto free;
> +
> +	if (acpi_table_parse("IVRS", init_memory_definitions) != 0)
> +		goto free;
> +
> +	printk(KERN_INFO "AMD IOMMU: aperture size is %d MB\n",
> +			(1 << (amd_iommu_aperture_order-20)));
> +
> +	printk(KERN_INFO "AMD IOMMU: device isolation ");
> +	if (amd_iommu_isolate)
> +		printk("enabled\n");
> +	else
> +		printk("disabled\n");
> +
> +out:
> +	return ret;
> +
> +free:
> +	if (amd_iommu_pd_alloc_bitmap)
> +		free_pages((unsigned long)amd_iommu_pd_alloc_bitmap, 1);
> +
> +	if (amd_iommu_pd_table)
> +		free_pages((unsigned long)amd_iommu_pd_table,
> +				get_order(rlookup_table_size));
> +
> +	if (amd_iommu_rlookup_table)
> +		free_pages((unsigned long)amd_iommu_rlookup_table,
> +				get_order(rlookup_table_size));
> +
> +	if (amd_iommu_alias_table)
> +		free_pages((unsigned long)amd_iommu_alias_table,
> +				get_order(alias_table_size));
> +
> +	if (amd_iommu_dev_table)
> +		free_pages((unsigned long)amd_iommu_dev_table,
> +				get_order(dev_table_size));

free_pages(0) is legal, so all these tests are unneeded, I expect.

This remains true if you decide to switch to kzalloc().

> +	free_iommu_all();
> +
> +	free_unity_maps();
> +
> +	goto out;
> +}

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