Re: [Qemu-devel] [Qemu-block] [PATCH] nvme: add Get/Set Feature Timestamp support

[Klaus Birkelund <klaus@birkelund.eu>]

On Fri, May 17, 2019 at 07:49:18PM -0600, Heitke, Kenneth wrote:
> > > > > > +        if (qemu_iovec_from_buf(&iov, 0, ptr, len) != len) {
> > > > > 
> > > > > This should be `qemu_iovec_to_buf`.
> > > > > 
> > > > 
> > > > This function is transferring data from the "host" to the device so I
> > > > believe I am using the correct function.
> > > > 
> > > 
> > > Exactly, but this means that you need to populate `ptr` with data
> > > described by the prps, hence dma_buf_*write* and qemu_iovec_*to*_buf. In
> > > this case `ptr` is set to the address of the uint64_t timestamp, and
> > > that is what we need to write to.
> > > 
> > 
> > I was going to argue with the fact that nvme_dma_read_prp uses
> > qemu_iovec_from_buf. But it uses _to_buf which as far as I can tell is
> > also wrong.
> > 
> 
> Okay, I'm onboard. You're correct. I'll update my patch and re-submit. I can
> also submit a patch to fix nvme_dma_read_prp() unless you or someone else
> wants to.
> 

Hi Kenneth,

The `nvme_dma_read_prp` case is actually already fixed in one of the
patches I sent yesterday ("nvme: simplify PRP mappings"), but I'll
submit it as a separate patch.

Cheers