Re: [PATCH v3 3/4] hw/block/nvme: Fix pmrmsc register size

[Klaus Jensen]

On Jun 30 17:16, Philippe Mathieu-Daudé wrote:
> On 6/30/20 5:10 PM, Andrzej Jakowski wrote:
> > On 6/30/20 4:04 AM, Philippe Mathieu-Daudé wrote:
> >> The Persistent Memory Region Controller Memory Space Control
> >> register is 64-bit wide. See 'Figure 68: Register Definition'
> >> of the 'NVM Express Base Specification Revision 1.4'.
> >>
> >> Fixes: 6cf9413229 ("introduce PMR support from NVMe 1.4 spec")
> >> Reported-by: Klaus Jensen <k.jensen@samsung.com>
> >> Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
> >> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> >> ---
> >> Cc: Andrzej Jakowski <andrzej.jakowski@linux.intel.com>
> >> ---
> >>  include/block/nvme.h | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/include/block/nvme.h b/include/block/nvme.h
> >> index 71c5681912..82c384614a 100644
> >> --- a/include/block/nvme.h
> >> +++ b/include/block/nvme.h
> >> @@ -21,7 +21,7 @@ typedef struct QEMU_PACKED NvmeBar {
> >>      uint32_t    pmrsts;
> >>      uint32_t    pmrebs;
> >>      uint32_t    pmrswtp;
> >> -    uint32_t    pmrmsc;
> >> +    uint64_t    pmrmsc;
> >>  } NvmeBar;
> >>  
> >>  enum NvmeCapShift {
> >> -- 2.21.3
> > 
> > This is good catch, though I wanted to highlight that this will still 
> > need to change as this register is not aligned properly and thus not in
> > compliance with spec.
> 
> I was wondering the odd alignment too. So you are saying at some time
> in the future the spec will be updated to correct the alignment?
> 
> Should we use this instead?
> 
>       uint32_t    pmrmsc;
>  +    uint32_t    pmrmsc_upper32; /* the spec define this, but *
>  +                                 * only low 32-bit are used  */
> 
> Or eventually an unnamed struct:
> 
>  -    uint32_t    pmrmsc;
>  +    struct {
>  +        uint32_t pmrmsc;
>  +        uint32_t pmrmsc_upper32; /* the spec define this, but *
>  +                                  * only low 32-bit are used  */
>  +    };
> 
> > 
> > Reviewed-by Andrzej Jakowski <andrzej.jakowski@linux.intel.com>
> > 
> 

I'm also not sure what you mean Andrzej. The odd alignment is exactly
what the spec (v1.4) says?