This is a note to let you know that I've just added the patch titled
cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cxl-pci-fix-disabling-memory-if-dvsec-cxl-range-does-not-match-a-cfmws-window.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 0cab687205986491302cd2e440ef1d253031c221 Mon Sep 17 00:00:00 2001
From: Robert Richter <rrichter@xxxxxxx>
Date: Fri, 16 Feb 2024 17:01:13 +0100
Subject: cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window
From: Robert Richter <rrichter@xxxxxxx>
commit 0cab687205986491302cd2e440ef1d253031c221 upstream.
The Linux CXL subsystem is built on the assumption that HPA == SPA.
That is, the host physical address (HPA) the HDM decoder registers are
programmed with are system physical addresses (SPA).
During HDM decoder setup, the DVSEC CXL range registers (cxl-3.1,
8.1.3.8) are checked if the memory is enabled and the CXL range is in
a HPA window that is described in a CFMWS structure of the CXL host
bridge (cxl-3.1, 9.18.1.3).
Now, if the HPA is not an SPA, the CXL range does not match a CFMWS
window and the CXL memory range will be disabled then. The HDM decoder
stops working which causes system memory being disabled and further a
system hang during HDM decoder initialization, typically when a CXL
enabled kernel boots.
Prevent a system hang and do not disable the HDM decoder if the
decoder's CXL range is not found in a CFMWS window.
Note the change only fixes a hardware hang, but does not implement
HPA/SPA translation. Support for this can be added in a follow on
patch series.
Signed-off-by: Robert Richter <rrichter@xxxxxxx>
Fixes: 34e37b4c432c ("cxl/port: Enable HDM Capability after validating DVSEC Ranges")
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240216160113.407141-1-rrichter@xxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cxl/core/pci.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -376,9 +376,9 @@ static bool __cxl_hdm_decode_init(struct
allowed++;
}
- if (!allowed) {
- cxl_set_mem_enable(cxlds, 0);
- info->mem_enabled = 0;
+ if (!allowed && info->mem_enabled) {
+ dev_err(dev, "Range register decodes outside platform defined CXL ranges.\n");
+ return -ENXIO;
}
/*
Patches currently in stable-queue which might be from rrichter@xxxxxxx are
queue-6.1/cxl-pci-fix-disabling-memory-if-dvsec-cxl-range-does-not-match-a-cfmws-window.patch
