Re: [PATCH] hw/nvme: Add support for setting the MQES for the NVMe emulation

["Berg, John" <jhnberg@amazon.co.uk>]

On Thu, 2024-04-04 at 15:01 +0200, Klaus Jensen wrote:
> On Apr  4 13:04, John Berg wrote:
> > From: John Berg <jhnberg@amazon.com>
> > 
> > The MQES field in the CAP register describes the Maximum Queue
> > Entries
> > Supported for the IO queues of an NVMe controller. Adding a +1 to
> > the
> > value in this field results in the total queue size. A full queue
> > is
> > when a queue of size N contains N - 1 entries, and the minimum
> > queue
> > size is 2. Thus the lowest MQES value is 1.
> > 
> > This patch adds the new mqes property to the NVMe emulation which
> > allows
> > a user to specify the maximum queue size by setting this property.
> > This
> > is useful as it enables testing of NVMe controller where the MQES
> > is
> > relatively small. The smallest NVMe queue size supported in NVMe is
> > 2
> > submission and completion entries, which means that the smallest
> > legal
> > mqes value is 1.
> > 
> > The following example shows how the mqes can be set for a the NVMe
> > emulation:
> > 
> > -drive id=nvme0,if=none,file=nvme.img,format=raw
> > -device nvme,drive=nvme0,serial=foo,mqes=1
> > 
> > If the mqes property is not provided then the default mqes will
> > still be
> > 0x7ff (the queue size is 2048 entries).
> > 
> > Signed-off-by: John Berg <jhnberg@amazon.co.uk>
> > ---
> >  hw/nvme/ctrl.c | 9 ++++++++-
> >  hw/nvme/nvme.h | 1 +
> >  2 files changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
> > index 127c3d2383..86cda9bc73 100644
> > --- a/hw/nvme/ctrl.c
> > +++ b/hw/nvme/ctrl.c
> > @@ -7805,6 +7805,12 @@ static bool nvme_check_params(NvmeCtrl *n,
> > Error **errp)
> >          return false;
> >      }
> >  
> > +    if (params->mqes < 1)
> > +    {
> 
> Please keep the `{` on the same line as the `if`. I think
> checkpatch.pl
> should catch this.
> 
> No need to send a v2, I'll fix it up when I apply it to nvme-next :)
> 
> Thanks!


Hello

Sorry for chasing. I was just wondering when this patch will be
applied. I can send a second revision if that helps.

Kind regards,
John