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Date: Mon, 06 Jan 2014 09:41:29 +0800
From: "Li, ZhenHua" <zhen-hual@...com>
To: "Wu, Feng" <feng.wu@...el.com>
CC: Kai Huang <dev.kai.huang@...il.com>,
David Woodhouse <dwmw2@...radead.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] x86/iommu: use bit structures for context_entry
Yes, that's the problem. And some other structures like this, see "union
irte".
On 12/26/2013 01:12 PM, Wu, Feng wrote:
> I think if using |= operation, it should use &= operation to clear those
> bits first.
>
> Thanks,
>
> Feng
>
> *From:*iommu-bounces@...ts.linux-foundation.org
> [mailto:iommu-bounces@...ts.linux-foundation.org] *On Behalf Of *Kai Huang
> *Sent:* Thursday, December 26, 2013 9:55 AM
> *To:* Li, Zhen-Hua
> *Cc:* David Woodhouse; iommu@...ts.linux-foundation.org;
> linux-kernel@...r.kernel.org
> *Subject:* Re: [PATCH 1/1] x86/iommu: use bit structures for context_entry
>
> Just curious, why would |= operation cause problem? :)
>
> On Fri, Dec 20, 2013 at 4:45 PM, Li, Zhen-Hua <zhen-hual@...com
> <mailto:zhen-hual@...com>> 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 <mailto: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)
> --
> 1.8.4.3
>
> _______________________________________________
> iommu mailing list
> iommu@...ts.linux-foundation.org <mailto:iommu@...ts.linux-foundation.org>
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>
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