Re: [RFC PATCH 1/5] cxl/core: correct length of DPA field masks

[Shiyang Ruan]

在 2024/2/10 14:34, 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.
>
> Can you include this user visible side-effect of this change. Looks like
> this could cause usages of CXL_DPA_FLAGS_MASK to return an incorrect
> result?

Ok.  Will change it to this:

The length of Physical Address in General Media Event Record/DRAM Event 
Record is 64bit, per CXL Spec r3.0 - 8.2.9.2.1.1, Table 8-43.  Currently 
CXL_DPA_FLAGS_MASK is defined as int (32bit), then CXL_DPA_MASK is a int 
too, it will be 0x00000000FFFFFFC0 while using "->dpa & CXL_DPA_MASK" to 
obtain real physical address (to drop flags in lower bits), in this case 
the higher 32bit of ->dpa will be lost.

To avoid this, define CXL_DPA_FLAGS_MASK as 64bit: 0x3FULL.


--
Thanks,
Ruan.

> > 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 89445435303a..388a87d972c2 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"      }  \
> > --
> > 2.34.1