Re: [PATCH v2] hw/nvme: clean up CC register write logic

[Łukasz Gieryk]

On Fri, Jun 03, 2022 at 10:24:51PM +0200, Klaus Jensen wrote:
> On Jun  1 15:28, Lukasz Maniak wrote:
> > On Wed, May 25, 2022 at 09:35:24AM +0200, Klaus Jensen wrote:
> > > 
> > > +        stl_le_p(&n->bar.intms, 0);
> > > +        stl_le_p(&n->bar.intmc, 0);
> > > +        stl_le_p(&n->bar.cc, 0);
> > 
> > Looks fine, though it seems the NVMe spec says the above registers
> > should be cleared during each reset for VF as well.
> > 
> 
> Aren't the values of all other registers than CSTS just undefined? (NVMe
> v2.0b, Section 8.26.3)

My 2 cents –

When VF is online:
- Both Controller Reset (CR) and PCIe Function Level Reset (FLR) can be
  issued to given VF
- Both resets shall return all (except specific) Nvme registers of given
  VF to their reset values (3.7.2)

When VF is offline:
- CR cannot be issued (only CSTS is defined, writes to CC are dropped),
  so doesn’t need an explicit IF
- FLR is allowed as it’s a part of the procedure to bring VF online
  (mentioned in 8.26.3)
- At least FLR shall reset the registers for VF

So I agree with the other Lukasz's suggestion. I would also clear
intms/intmc/cc for both: VF and PF reset paths, regardless of the actual
reset type.