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

In the Linux kernel, the following vulnerability has been resolved:

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

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.