From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: <linux-kernel@vger.kernel.org>,
Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>,
David Airlie <airlied@linux.ie>,
"Daniel Vetter" <daniel@ffwll.ch>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Dan Carpenter <dan.carpenter@oracle.com>, Wei Liu <wl@xen.org>,
"Yan Yankovskyi" <yyankovskyi@gmail.com>,
<dri-devel@lists.freedesktop.org>,
<xen-devel@lists.xenproject.org>, <linux-mm@kvack.org>,
David Hildenbrand <david@redhat.com>,
Michal Hocko <mhocko@kernel.org>,
Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH v4 2/2] xen: add helpers to allocate unpopulated memory
Date: Fri, 14 Aug 2020 11:56:29 +0200 [thread overview]
Message-ID: <20200814095629.GJ975@Air-de-Roger> (raw)
In-Reply-To: <20200814072920.GA6126@infradead.org>
On Fri, Aug 14, 2020 at 08:29:20AM +0100, Christoph Hellwig wrote:
> On Thu, Aug 13, 2020 at 09:54:20AM +0200, Roger Pau Monn?? wrote:
> > On Thu, Aug 13, 2020 at 08:33:37AM +0100, Christoph Hellwig wrote:
> > > On Tue, Aug 11, 2020 at 11:44:47AM +0200, Roger Pau Monne wrote:
> > > > If enabled (because ZONE_DEVICE is supported) the usage of the new
> > > > functionality untangles Xen balloon and RAM hotplug from the usage of
> > > > unpopulated physical memory ranges to map foreign pages, which is the
> > > > correct thing to do in order to avoid mappings of foreign pages depend
> > > > on memory hotplug.
> > >
> > > So please just select ZONE_DEVICE if this is so much better rather
> > > than maintaining two variants.
> >
> > We still need to other variant for Arm at least, so both need to be
> > maintained anyway, even if we force ZONE_DEVICE on x86.
>
> Well, it still really helps reproducability if you stick to one
> implementation of x86.
>
> The alternative would be an explicit config option to opt into it,
> but just getting a different implementation based on a random
> kernel option is strange.
Would adding something like the chunk below to the patch be OK?
---8<---
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 018020b91baa..5f321a1319e6 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -328,7 +328,14 @@ config XEN_FRONT_PGDIR_SHBUF
tristate
config XEN_UNPOPULATED_ALLOC
- bool
- default y if ZONE_DEVICE && !ARM && !ARM64
+ bool "Use unpopulated memory ranges for guest mappings"
+ depends on X86
+ select ZONE_DEVICE
+ default y
+ help
+ Use unpopulated memory ranges in order to create mappings for guest
+ memory regions, including grants maps and foreign pages. This avoids
+ having to balloon out RAM regions in order to obtain physical memory
+ space to create such mappings.
endmenu
next prev parent reply other threads:[~2020-08-14 9:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200811094447.31208-1-roger.pau@citrix.com>
2020-08-11 9:44 ` [PATCH v4 1/2] memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC Roger Pau Monne
2020-08-11 21:07 ` David Hildenbrand
2020-08-20 11:37 ` Roger Pau Monné
2020-08-31 10:19 ` Roger Pau Monné
2020-08-31 20:56 ` Ira Weiny
2020-08-31 19:20 ` Andrew Morton
2020-08-11 9:44 ` [PATCH v4 2/2] xen: add helpers to allocate unpopulated memory Roger Pau Monne
2020-08-12 7:28 ` Jürgen Groß
2020-08-12 7:38 ` Roger Pau Monné
2020-08-13 7:33 ` Christoph Hellwig
2020-08-13 7:54 ` Roger Pau Monné
2020-08-13 9:49 ` Daniel Vetter
2020-08-13 10:02 ` Roger Pau Monné
2020-08-14 7:29 ` Christoph Hellwig
2020-08-14 9:56 ` Roger Pau Monné [this message]
2020-08-14 10:27 ` Jürgen Groß
2020-08-14 12:47 ` Roger Pau Monné
2020-08-14 12:54 ` Jürgen Groß
2020-08-14 13:35 ` Roger Pau Monné
2020-08-14 13:52 ` Jürgen Groß
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200814095629.GJ975@Air-de-Roger \
--to=roger.pau@citrix.com \
--cc=airlied@linux.ie \
--cc=boris.ostrovsky@oracle.com \
--cc=dan.carpenter@oracle.com \
--cc=dan.j.williams@intel.com \
--cc=daniel@ffwll.ch \
--cc=david@redhat.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=hch@infradead.org \
--cc=jgross@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=oleksandr_andrushchenko@epam.com \
--cc=sstabellini@kernel.org \
--cc=wl@xen.org \
--cc=xen-devel@lists.xenproject.org \
--cc=yyankovskyi@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).