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-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; io...@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 <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
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