diff mbox series

[RFC,v2,1/6] cxl/core: correct length of DPA field masks

Message ID 20240329063614.362763-2-ruansy.fnst@fujitsu.com
State New, archived
Headers show
Series cxl: add poison event handler | expand

Commit Message

Shiyang Ruan March 29, 2024, 6:36 a.m. UTC
The length of Physical Address in General Media Event Record/DRAM Event
Record is 64-bit, so the field mask should be defined as such length.
Otherwise, this causes cxl_general_media and cxl_dram tracepoints to
mask off the upper-32-bits of DPA addresses. The cxl_poison event is
unaffected.

If userspace was doing its own DPA-to-HPA translation this could lead to
incorrect page retirement decisions, but there is no known consumer
(like rasdaemon) of this event today.

Fixes: d54a531a430b ("cxl/mem: Trace General Media Event Record")
Cc: <stable@vger.kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
 drivers/cxl/core/trace.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Dan Williams March 30, 2024, 1:37 a.m. UTC | #1
Shiyang Ruan wrote:
> The length of Physical Address in General Media Event Record/DRAM Event
> Record is 64-bit, so the field mask should be defined as such length.
> Otherwise, this causes cxl_general_media and cxl_dram tracepoints to
> mask off the upper-32-bits of DPA addresses. The cxl_poison event is
> unaffected.
> 
> If userspace was doing its own DPA-to-HPA translation this could lead to
> incorrect page retirement decisions, but there is no known consumer
> (like rasdaemon) of this event today.
> 
> Fixes: d54a531a430b ("cxl/mem: Trace General Media Event Record")
> Cc: <stable@vger.kernel.org>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> ---
>  drivers/cxl/core/trace.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
> index e5f13260fc52..e2d1f296df97 100644
> --- a/drivers/cxl/core/trace.h
> +++ b/drivers/cxl/core/trace.h
> @@ -253,11 +253,11 @@ TRACE_EVENT(cxl_generic_event,
>   * DRAM Event Record
>   * CXL rev 3.0 section 8.2.9.2.1.2; Table 8-44
>   */
> -#define CXL_DPA_FLAGS_MASK			0x3F
> +#define CXL_DPA_FLAGS_MASK			0x3FULL

This change makes sense...

>  #define CXL_DPA_MASK				(~CXL_DPA_FLAGS_MASK)
>  
> -#define CXL_DPA_VOLATILE			BIT(0)
> -#define CXL_DPA_NOT_REPAIRABLE			BIT(1)
> +#define CXL_DPA_VOLATILE			BIT_ULL(0)
> +#define CXL_DPA_NOT_REPAIRABLE			BIT_ULL(1)

...these do not. The argument to __print_flags() is an unsigned long, so
they will be cast down to (unsigned long), and they are never used as a
mask so the generated code should not change.
Shiyang Ruan April 1, 2024, 9:14 a.m. UTC | #2
在 2024/3/30 9:37, Dan Williams 写道:
> Shiyang Ruan wrote:
>> The length of Physical Address in General Media Event Record/DRAM Event
>> Record is 64-bit, so the field mask should be defined as such length.
>> Otherwise, this causes cxl_general_media and cxl_dram tracepoints to
>> mask off the upper-32-bits of DPA addresses. The cxl_poison event is
>> unaffected.
>>
>> If userspace was doing its own DPA-to-HPA translation this could lead to
>> incorrect page retirement decisions, but there is no known consumer
>> (like rasdaemon) of this event today.
>>
>> Fixes: d54a531a430b ("cxl/mem: Trace General Media Event Record")
>> Cc: <stable@vger.kernel.org>
>> Cc: Dan Williams <dan.j.williams@intel.com>
>> Cc: Davidlohr Bueso <dave@stgolabs.net>
>> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> Cc: Ira Weiny <ira.weiny@intel.com>
>> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
>> ---
>>   drivers/cxl/core/trace.h | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
>> index e5f13260fc52..e2d1f296df97 100644
>> --- a/drivers/cxl/core/trace.h
>> +++ b/drivers/cxl/core/trace.h
>> @@ -253,11 +253,11 @@ TRACE_EVENT(cxl_generic_event,
>>    * DRAM Event Record
>>    * CXL rev 3.0 section 8.2.9.2.1.2; Table 8-44
>>    */
>> -#define CXL_DPA_FLAGS_MASK			0x3F
>> +#define CXL_DPA_FLAGS_MASK			0x3FULL
> 
> This change makes sense...
> 
>>   #define CXL_DPA_MASK				(~CXL_DPA_FLAGS_MASK)
>>   
>> -#define CXL_DPA_VOLATILE			BIT(0)
>> -#define CXL_DPA_NOT_REPAIRABLE			BIT(1)
>> +#define CXL_DPA_VOLATILE			BIT_ULL(0)
>> +#define CXL_DPA_NOT_REPAIRABLE			BIT_ULL(1)
> 
> ...these do not. The argument to __print_flags() is an unsigned long, so
> they will be cast down to (unsigned long), and they are never used as a
> mask so the generated code should not change.

They will only used to check if such flag is set, not used as mask.  So, 
yes, I'll remove these changes.


--
Thanks,
Ruan.
diff mbox series

Patch

diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
index e5f13260fc52..e2d1f296df97 100644
--- a/drivers/cxl/core/trace.h
+++ b/drivers/cxl/core/trace.h
@@ -253,11 +253,11 @@  TRACE_EVENT(cxl_generic_event,
  * DRAM Event Record
  * CXL rev 3.0 section 8.2.9.2.1.2; Table 8-44
  */
-#define CXL_DPA_FLAGS_MASK			0x3F
+#define CXL_DPA_FLAGS_MASK			0x3FULL
 #define CXL_DPA_MASK				(~CXL_DPA_FLAGS_MASK)
 
-#define CXL_DPA_VOLATILE			BIT(0)
-#define CXL_DPA_NOT_REPAIRABLE			BIT(1)
+#define CXL_DPA_VOLATILE			BIT_ULL(0)
+#define CXL_DPA_NOT_REPAIRABLE			BIT_ULL(1)
 #define show_dpa_flags(flags)	__print_flags(flags, "|",		   \
 	{ CXL_DPA_VOLATILE,			"VOLATILE"		}, \
 	{ CXL_DPA_NOT_REPAIRABLE,		"NOT_REPAIRABLE"	}  \