I think if using |= operation, it should use &= operation to clear those bits first.
Thanks, Feng From: iommu-boun...@lists.linux-foundation.org [mailto:iommu-boun...@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-ker...@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 <zhen-h...@hp.com<mailto:zhen-h...@hp.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-h...@hp.com<mailto:zhen-h...@hp.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@lists.linux-foundation.org<mailto:iommu@lists.linux-foundation.org> https://lists.linuxfoundation.org/mailman/listinfo/iommu
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