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

From: Andrew Morton
Date: Wed Jul 09 2008 - 21:53:40 EST


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