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POWER9 DD2.1 and earlier has an issue where some cache inhibited vector load will return bad data. The workaround is two part, one firmware/microcode part triggers HMI interrupts when hitting such loads, the other part is this patch which then emulates the instructions in Linux. The affected instructions are limited to lxvd2x, lxvw4x, lxvb16x and lxvh8x. When an instruction triggers the HMI, all threads in the core will be sent to the HMI handler, not just the one running the vector load. In general, these spurious HMIs are detected by the emulation code and we just return back to the running process. Unfortunately, if a spurious interrupt occurs on a vector load that's to normal memory we have no way to detect that it's spurious (unless we walk the page tables, which is very expensive). In this case we emulate the load but we need do so using a vector load itself to ensure 128bit atomicity is preserved. Some additional debugfs emulated instruction counters are added also. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [mpe: Switch CONFIG_PPC_BOOK3S_64 to CONFIG_VSX to unbreak the build] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.