linux-kernel - Re: [PATCH v5 5/8] iommu/amd: copy old trans table from old kernel

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Date:   Tue, 20 Sep 2016 14:40:31 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Baoquan He <bhe@...hat.com>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, dyoung@...hat.com, xlpang@...hat.com,
        Vincent.Wan@....com
Subject: Re: [PATCH v5 5/8] iommu/amd: copy old trans table from old kernel

On Thu, Sep 15, 2016 at 11:03:23PM +0800, Baoquan He wrote:
> Here several things need be done:
> 1) If iommu is pre-enabled in a normal kernel, just disable it and print
>    warning.
> 2) If failed to copy dev table of old kernel, continue to proceed as
>    it does in normal kernel.
> 3) Re-enable event/cmd buffer and install the new DTE table to reg.
> 4) Flush all caches
> 
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  drivers/iommu/amd_iommu_init.c | 44 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 41 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
> index ce49641..47a8fc9 100644
> --- a/drivers/iommu/amd_iommu_init.c
> +++ b/drivers/iommu/amd_iommu_init.c
> @@ -34,7 +34,7 @@
>  #include <asm/iommu_table.h>
>  #include <asm/io_apic.h>
>  #include <asm/irq_remapping.h>
> -
> +#include <linux/crash_dump.h>

Please keep that empty line, it is there for readability.

>  #include "amd_iommu_proto.h"
>  #include "amd_iommu_types.h"
>  #include "irq_remapping.h"
> @@ -1344,6 +1344,12 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
>  	iommu->int_enabled = false;
>  
>  	init_translation_status(iommu);
> +	if (translation_pre_enabled(iommu) && !is_kdump_kernel()) {
> +		iommu_disable(iommu);
> +		clear_translation_pre_enabled(iommu);
> +		pr_warn("Translation was enabled for IOMMU:%d but we are not in kdump mode\n",
> +			iommu->index);
> +	}
>  
>  	if (translation_pre_enabled(iommu))
>  		pr_warn("Translation is already enabled - trying to copy translation structures\n");
> @@ -1946,9 +1952,41 @@ static void early_enable_iommu(struct amd_iommu *iommu)
>  static void early_enable_iommus(void)
>  {
>  	struct amd_iommu *iommu;
> +	bool is_pre_enabled=false;
>  
> -	for_each_iommu(iommu)
> -		early_enable_iommu(iommu);
> +	for_each_iommu(iommu) {
> +		if ( translation_pre_enabled(iommu) ) {

Coding style, too many spaces. There is more of that below.

> +			is_pre_enabled = true;
> +			break;
> +		}
> +	}
> +
> +	if ( !is_pre_enabled) {
> +		for_each_iommu(iommu)
> +			early_enable_iommu(iommu);
> +	} else {
> +		if (copy_dev_tables()) {
> +			pr_err("Failed to copy DEV table from previous kernel.\n");
> +			/*
> +			 * If failed to copy dev tables from old kernel, continue to proceed
> +			 * as it does in normal kernel.
> +			 */
> +			for_each_iommu(iommu) {
> +				clear_translation_pre_enabled(iommu);
> +				early_enable_iommu(iommu);
> +			}
> +		} else {
> +			pr_info("Copied DEV table from previous kernel.\n");
> +			for_each_iommu(iommu) {
> +				iommu_feature_disable(iommu, CONTROL_CMDBUF_EN);
> +		                iommu_feature_disable(iommu, CONTROL_EVT_LOG_EN);

Could you move that into new helpers (iommu_disable_command_buffer...)?

> +		                iommu_enable_command_buffer(iommu);
> +		                iommu_enable_event_buffer(iommu);
> +		                iommu_set_device_table(iommu);
> +		                iommu_flush_all_caches(iommu);
> +			}
> +		}
> +	}
>  }
>  
>  static void enable_iommus_v2(void)
> -- 
> 2.5.5
>