linux-kernel - [PATCH 0/6] dax/hmem, cxl: Coordinate Soft Reserved handling with CXL

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Message-ID: <20250822034202.26896-1-Smita.KoralahalliChannabasappa@amd.com>
Date: Fri, 22 Aug 2025 03:41:56 +0000
From: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
To: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<nvdimm@...ts.linux.dev>, <linux-fsdevel@...r.kernel.org>,
	<linux-pm@...r.kernel.org>
CC: Davidlohr Bueso <dave@...olabs.net>, Jonathan Cameron
	<jonathan.cameron@...wei.com>, Dave Jiang <dave.jiang@...el.com>, "Alison
 Schofield" <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Matthew Wilcox <willy@...radead.org>, Jan Kara
	<jack@...e.cz>, "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown
	<len.brown@...el.com>, Pavel Machek <pavel@...nel.org>, Li Ming
	<ming.li@...omail.com>, Jeff Johnson <jeff.johnson@....qualcomm.com>, "Ying
 Huang" <huang.ying.caritas@...il.com>, Yao Xingtao <yaoxt.fnst@...itsu.com>,
	Peter Zijlstra <peterz@...radead.org>, Greg KH <gregkh@...uxfoundation.org>,
	Nathan Fontenot <nathan.fontenot@....com>, Smita Koralahalli
	<Smita.KoralahalliChannabasappa@....com>, Terry Bowman
	<terry.bowman@....com>, Robert Richter <rrichter@....com>, Benjamin Cheatham
	<benjamin.cheatham@....com>, PradeepVineshReddy Kodamati
	<PradeepVineshReddy.Kodamati@....com>, Zhijian Li <lizhijian@...itsu.com>
Subject: [PATCH 0/6] dax/hmem, cxl: Coordinate Soft Reserved handling with CXL

This series aims to address long-standing conflicts between dax_hmem and
CXL when handling Soft Reserved memory ranges.

I have considered adding support for DAX_CXL_MODE_REGISTER, but I do not
yet have a solid approach. Since this came up in discussion yesterday,
I am sending the current work and would appreciate inputs on how best to
handle the DAX_CXL_MODE_REGISTER case.

Reworked from Dan's patch:
https://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl.git/patch/?id=ab70c6227ee6165a562c215d9dcb4a1c55620d5d

Previous work:
https://lore.kernel.org/all/20250715180407.47426-1-Smita.KoralahalliChannabasappa@amd.com/

Smita Koralahalli (6):
  dax/hmem, e820, resource: Defer Soft Reserved registration until hmem
    is ready
  dax/hmem: Request cxl_acpi and cxl_pci before walking Soft Reserved
    ranges
  dax/hmem, cxl: Tighten dependencies on DEV_DAX_CXL and dax_hmem
  dax/hmem: Defer Soft Reserved overlap handling until CXL region
    assembly completes
  dax/hmem: Reintroduce Soft Reserved ranges back into the iomem tree
  cxl/region, dax/hmem: Guard CXL DAX region creation and tighten HMEM
    deps

 arch/x86/kernel/e820.c    |   2 +-
 drivers/cxl/core/region.c |   4 +-
 drivers/dax/Kconfig       |   3 +
 drivers/dax/hmem/device.c |   4 +-
 drivers/dax/hmem/hmem.c   | 137 +++++++++++++++++++++++++++++++++++---
 include/linux/ioport.h    |  24 +++++++
 kernel/resource.c         |  73 +++++++++++++++++---
 7 files changed, 222 insertions(+), 25 deletions(-)

-- 
2.17.1