Re: [dpdk-dev] [PATCH 19.11] vfio: fix DMA mapping of externally allocated heaps

From: Thomas Monjalon <thomas@monjalon.net>
To: David Marchand <david.marchand@redhat.com>,
	Anatoly Burakov <anatoly.burakov@intel.com>
Cc: dev <dev@dpdk.org>, Bruce Richardson <bruce.richardson@intel.com>,
	Rajesh Ravi <rajesh.ravi@broadcom.com>,
	Ajit Khaparde <ajit.khaparde@broadcom.com>,
	Jonathan Richardson <jonathan.richardson@broadcom.com>,
	Scott Branden <scott.branden@broadcom.com>,
	Vikram Mysore Prakash <vikram.prakash@broadcom.com>,
	Srinath Mannam <srinath.mannam@broadcom.com>,
	Kevin Traynor <ktraynor@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 19.11] vfio: fix DMA mapping of externally allocated heaps
Date: Wed, 06 Nov 2019 23:12:00 +0100	[thread overview]
Message-ID: <12687014.fTV4V1tnDX@xps> (raw)
In-Reply-To: <CAJFAV8yL-hYToxEkCds+90tXemhGDNjnWB91+0vRC0i=whODRQ@mail.gmail.com>

06/11/2019 22:53, David Marchand:
> On Tue, Nov 5, 2019 at 4:15 PM Anatoly Burakov
> <anatoly.burakov@intel.com> wrote:
> >
> > Currently, externally created heaps are supposed to be automatically
> > mapped for VFIO DMA by EAL, however they only do so if, at the time of
> > heap creation, VFIO is initialized and has at least one device
> > available. If no devices are available at the time of heap creation (or
> > if devices were available, but were since hot-unplugged, thus dropping
> > all VFIO container mappings), then VFIO mapping code would have skipped
> > over externally allocated heaps.
> >
> > The fix is two-fold. First, we allow externally allocated memory
> > segments to be marked as "heap" segments. This allows us to distinguish
> > between external memory segments that were created via heap API, from
> > those that were created via rte_extmem_register() API.
> >
> > Then, we fix the VFIO code to only skip non-heap external segments.
> > Also, since external heaps are not guaranteed to have valid IOVA
> > addresses, we will skip those which have invalid IOVA addresses as well.
> >
> > Fixes: 0f526d674f8e ("malloc: separate creating memseg list and malloc heap")
> >
> > Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> > ---
> >
> > Notes:
> >     This cannot be backported to older releases as it breaks the
> >     API and ABI. A separate fix is in the works for stable.
> 
> I'd say we still have to Cc: stable, on the principle so that the
> stable maintainers know there is an issue on this commit.

Yes I agree. Cc: stable should be in this commit log.
Adding Cc: stable does not mean the patch can be backported without any effort :)