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cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window 

commit 0cab687205 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@amd.com>
Fixes: 34e37b4c43 ("cxl/port: Enable HDM Capability after validating DVSEC Ranges")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20240216160113.407141-1-rrichter@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Robert Richter 2024-02-16 17:01:13 +01:00 committed by Greg Kroah-Hartman
parent 27c1ade606
commit 0312171289
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/cxl/core/pci.c
View File

@ -376,9 +376,9 @@ static bool __cxl_hdm_decode_init(struct cxl_dev_state *cxlds,
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;
}
/*