linux-kernel - Re: [PATCH 1/1] x86/iommu: use bit structures for context

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Date:	Fri, 10 Jan 2014 16:31:41 +0800
From:	"Li, ZhenHua" <zhen-hual@...com>
To:	"Li, Zhen-Hua" <zhen-hual@...com>
CC:	David Woodhouse <dwmw2@...radead.org>,
	Joerg Roedel <joro@...tes.org>,
	iommu@...ts.linux-foundation.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Wu, Feng" <feng.wu@...el.com>,
	Kai Huang <dev.kai.huang@...il.com>, jiang.liu@...ux.intel.com
Subject: Re: [PATCH 1/1] x86/iommu: use bit structures for context_entry

This patch is sent again because a ';' was missed in my last mail.

 > +	context->asr = value >> VTD_PAGE_SHIFT

I corrected it and created a new one. And it is tested .
Please use the latest one.


Sorry for that.

ZhenHua

On 01/10/2014 04:27 PM, Li, Zhen-Hua wrote:
> There is a structure named context_entry used by intel iommu, and there
> are some bit operations on it. Use bit structure may make these operations
> easy.
> Also the function context_set_address_root may cause problem because it uses
>   |= operation, not set the new value. And this patch can fix it.
>
> Signed-off-by: Li, Zhen-Hua <zhen-hual@...com>
> ---
>   drivers/iommu/intel-iommu.c | 37 +++++++++++++++++++++++++++----------
>   1 file changed, 27 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 43b9bfe..65cd480 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -221,47 +221,64 @@ get_context_addr_from_root(struct root_entry *root)
>    * 8-23: domain id
>    */
>   struct context_entry {
> -	u64 lo;
> -	u64 hi;
> +	union {
> +		struct {
> +			u64	present:1,
> +				fpd:1,
> +				translation_type:2,
> +				reserved_l:8,
> +				asr:52;
> +		};
> +		u64 lo;
> +	};
> +	union {
> +		struct {
> +			u64	aw:3,
> +				avail:4,
> +				reserved_h1:1,
> +				did:16,
> +				reserved_h2:40;
> +		};
> +		u64 hi;
> +	};
>   };
>
>   static inline bool context_present(struct context_entry *context)
>   {
> -	return (context->lo & 1);
> +	return context->present;
>   }
>   static inline void context_set_present(struct context_entry *context)
>   {
> -	context->lo |= 1;
> +	context->present = 1;
>   }
>
>   static inline void context_set_fault_enable(struct context_entry *context)
>   {
> -	context->lo &= (((u64)-1) << 2) | 1;
> +	context->fpd = 1;
>   }
>
>   static inline void context_set_translation_type(struct context_entry *context,
>   						unsigned long value)
>   {
> -	context->lo &= (((u64)-1) << 4) | 3;
> -	context->lo |= (value & 3) << 2;
> +	context->translation_type = value;
>   }
>
>   static inline void context_set_address_root(struct context_entry *context,
>   					    unsigned long value)
>   {
> -	context->lo |= value & VTD_PAGE_MASK;
> +	context->asr = value >> VTD_PAGE_SHIFT;
>   }
>
>   static inline void context_set_address_width(struct context_entry *context,
>   					     unsigned long value)
>   {
> -	context->hi |= value & 7;
> +	context->aw  = value;
>   }
>
>   static inline void context_set_domain_id(struct context_entry *context,
>   					 unsigned long value)
>   {
> -	context->hi |= (value & ((1 << 16) - 1)) << 8;
> +	context->did = value;
>   }
>
>   static inline void context_clear_entry(struct context_entry *context)
>

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