ACPI Platform Runtime Mechanism Support Is Getting Underway For Linux
Platform Runtime Mechanism, allows moving of the SMI handlers that do not require SMM privileges to be punted into the OS/VMM context. There are security and performance benefits of PRM and with it now being part of the public ACPI specification, the Linux kernel support is on its way. Microsoft for their part has already offered PRM support as part of Windows Insider Preview builds for months.
More background information on the Platform Runtime Mechanism can be found via the prior article Intel + Microsoft Continue Work On Replacing More SMM "Black Boxes" With PRM.
Now on the kernel front for the upcoming Linux 5.14, an initial PRM pull has landed into linux-pm's -next code. The pull has the initial changes for PRM and implementing the OperationRegion handler for this mechanism. A new Kconfig build time knob of ACPI_PRMT is added for that Platform Runtime Mechanism support.
More PRM technical information in general is available from the documentation.