Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752491AbaAFBll (ORCPT ); Sun, 5 Jan 2014 20:41:41 -0500 Received: from g6t0185.atlanta.hp.com ([15.193.32.62]:43700 "EHLO g6t0185.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752192AbaAFBlk (ORCPT ); Sun, 5 Jan 2014 20:41:40 -0500 Message-ID: <52CA09C9.7000205@hp.com> Date: Mon, 06 Jan 2014 09:41:29 +0800 From: "Li, ZhenHua" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: "Wu, Feng" CC: Kai Huang , David Woodhouse , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/1] x86/iommu: use bit structures for context_entry References: <1387529101-29769-1-git-send-email-zhen-hual@hp.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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@lists.linux-foundation.org > [mailto:iommu-bounces@lists.linux-foundation.org] *On Behalf Of *Kai Huang > *Sent:* Thursday, December 26, 2013 9:55 AM > *To:* Li, Zhen-Hua > *Cc:* David Woodhouse; iommu@lists.linux-foundation.org; > linux-kernel@vger.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 > 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 > > --- > 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@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/