CVE-2024-26761

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window<br /> <br /> The Linux CXL subsystem is built on the assumption that HPA == SPA.<br /> That is, the host physical address (HPA) the HDM decoder registers are<br /> programmed with are system physical addresses (SPA).<br /> <br /> During HDM decoder setup, the DVSEC CXL range registers (cxl-3.1,<br /> 8.1.3.8) are checked if the memory is enabled and the CXL range is in<br /> a HPA window that is described in a CFMWS structure of the CXL host<br /> bridge (cxl-3.1, 9.18.1.3).<br /> <br /> Now, if the HPA is not an SPA, the CXL range does not match a CFMWS<br /> window and the CXL memory range will be disabled then. The HDM decoder<br /> stops working which causes system memory being disabled and further a<br /> system hang during HDM decoder initialization, typically when a CXL<br /> enabled kernel boots.<br /> <br /> Prevent a system hang and do not disable the HDM decoder if the<br /> decoder&amp;#39;s CXL range is not found in a CFMWS window.<br /> <br /> Note the change only fixes a hardware hang, but does not implement<br /> HPA/SPA translation. Support for this can be added in a follow on<br /> patch series.