linux-kernel - Re: [PATCH 09/34] AMD IOMMU: add command buffer (de-)allocation

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Message-Id: <20080709184728.6d344e45.akpm@linux-foundation.org>
Date:	Wed, 9 Jul 2008 18:47:28 -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 09/34] AMD IOMMU: add command buffer (de-)allocation

On Thu, 26 Jun 2008 21:27:45 +0200 Joerg Roedel <joerg.roedel@....com> wrote:

> This patch adds the functions to allocate and deallocate the command buffer for
> one IOMMU in the system.
> 
> Signed-off-by: Joerg Roedel <joerg.roedel@....com>
> ---
>  arch/x86/kernel/amd_iommu_init.c |   30 ++++++++++++++++++++++++++++++
>  1 files changed, 30 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
> index ffb8ac8..c2be3ad 100644
> --- a/arch/x86/kernel/amd_iommu_init.c
> +++ b/arch/x86/kernel/amd_iommu_init.c
> @@ -278,3 +278,33 @@ static int __init find_last_devid_acpi(struct acpi_table_header *table)
>  	return 0;
>  }
>  
> +static u8 * __init alloc_command_buffer(struct amd_iommu *iommu)
> +{
> +	u8 *cmd_buf = (u8 *)__get_free_pages(GFP_KERNEL,
> +			get_order(CMD_BUFFER_SIZE));

Can use __GFP_ZERO here

> +	u64 entry = 0;

Unneeded initialisation.

> +	if (cmd_buf == NULL)
> +		return NULL;
> +
> +	iommu->cmd_buf_size = CMD_BUFFER_SIZE;
> +
> +	memset(cmd_buf, 0, CMD_BUFFER_SIZE);

And remove this.

> +	entry = (u64)virt_to_phys(cmd_buf);
> +	entry |= MMIO_CMD_SIZE_512;
> +	memcpy_toio(iommu->mmio_base + MMIO_CMD_BUF_OFFSET,
> +			&entry, sizeof(entry));
> +
> +	iommu_feature_enable(iommu, CONTROL_CMDBUF_EN);
> +
> +	return cmd_buf;
> +}
> +

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