From mboxrd@z Thu Jan  1 00:00:00 1970
From: kbusch@kernel.org (Keith Busch)
Date: Mon, 13 May 2019 09:16:52 -0600
Subject: [PATCH] nvme/pci: Use host managed power state for suspend
In-Reply-To: <20190513145708.GA25897@lst.de>
References: <20190510212937.11661-1-keith.busch@intel.com>
 <0080aaff18e5445dabca509d4113eca8@AUSX13MPC105.AMER.DELL.COM>
 <955722d8fc16425dbba0698c4806f8fd@AUSX13MPC105.AMER.DELL.COM>
 <20190513143754.GE15318@localhost.localdomain>
 <7ab8274ef1ce46fcae54a50abc76ae4a@AUSX13MPC105.AMER.DELL.COM>
 <20190513145708.GA25897@lst.de>
Message-ID: <20190513151652.GB15437@localhost.localdomain>

On Mon, May 13, 2019@04:57:08PM +0200, Christoph Hellwig wrote:
> On Mon, May 13, 2019@02:54:49PM +0000, Mario.Limonciello@dell.com wrote:
> > And NVME spec made it sound to me that while in a low power state it shouldn't
> > be available if the memory isn't available.
> > 
> > NVME spec in 8.9:
> > 
> > "Host software should request that the controller release the
> > assigned ranges prior to a shutdown event, a Runtime D3 event, or any other event
> > that requires host software to reclaim the assigned ranges."
> 
> The last part of the quoted text is the key - if the assigned range
> is reclaimed, that is the memory is going to be used for something else,
> we need to release the ranges.  But we do not release the ranges,
> as we want to keep the memory in use so that we can quickly use it
> again.

Yes, this. As far as I know, the host memory range is still accessible in
the idle suspend state. If there are states in which host memory is not
accessible, a reference explaining the requirement will be most helpful.