linux-kernel - Re: [PATCH v11 07/10] iommu/vt-d: enable kdump support in iommu module

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Date:	Wed, 13 May 2015 10:10:27 +0800
From:	Baoquan He <bhe@...hat.com>
To:	"Li, Zhen-Hua" <zhen-hual@...com>
Cc:	dwmw2@...radead.org, indou.takao@...fujitsu.com, joro@...tes.org,
	vgoyal@...hat.com, dyoung@...hat.com,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, kexec@...ts.infradead.org,
	alex.williamson@...hat.com, ddutile@...hat.com,
	ishii.hironobu@...fujitsu.com, bhelgaas@...gle.com,
	doug.hatch@...com, jerry.hoemann@...com, tom.vaden@...com,
	li.zhang6@...com, lisa.mitchell@...com, billsumnerlinux@...il.com,
	rwright@...com
Subject: Re: [PATCH v11 07/10] iommu/vt-d: enable kdump support in iommu
 module

On 05/11/15 at 05:52pm, Li, Zhen-Hua wrote:
> Modify the operation of the following functions when called during crash dump:
>     iommu_context_addr
>     free_context_table
>     get_domain_for_dev
>     init_dmars
>     intel_iommu_init
> 
> Bill Sumner:
>     Original version.
> 
> Zhenhua:
>     The name of new calling functions.
>     Do not disable and re-enable TE in kdump kernel.
>     Use the did and gaw from old context entry;
> 
> Signed-off-by: Bill Sumner <billsumnerlinux@...il.com>
> Signed-off-by: Li, Zhen-Hua <zhen-hual@...com>
> ---
>  drivers/iommu/intel-iommu.c | 95 +++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 83 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 28c3c64..91545bf 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -397,6 +397,7 @@ static int copy_root_entry_table(struct intel_iommu *iommu);
>  static int intel_iommu_load_translation_tables(struct intel_iommu *iommu);
>  
>  static void iommu_check_pre_te_status(struct intel_iommu *iommu);
> +static u8 g_translation_pre_enabled;
Hi Zhenhua,

I haven't checked patch one by one, am going through the code flow.

About g_translation_pre_enabled, I don't think it's necessary to define
it as a global variable. Both its assignment and judgement are in
init_dmars(). In this situation a local variable translation_pre_enabled
in init_dmars() is enough.

You can assign value to it here:

		iommu_check_pre_te_status(iommu);
		if (iommu->pre_enabled_trans) {
			translation_pre_enabled = 1;
			...
		}

Thanks
Baoquan
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