From: Dave Hansen <[email protected]> Finally allow CONFIG_KERNEL_PAGE_TABLE_ISOLATION to be enabled.
PARAVIRT generally requires that the kernel not manage its own page tables. It also means that the hypervisor and kernel must agree wholeheartedly about what format the page tables are in and what they contain. KERNEL_PAGE_TABLE_ISOLATION, unfortunately, changes the rules and they can not be used together. I've seen conflicting feedback from maintainers lately about whether they want the Kconfig magic to go first or last in a patch series. It's going last here because the partially-applied series leads to kernels that can not boot in a bunch of cases. I did a run through the entire series with CONFIG_KERNEL_PAGE_TABLE_ISOLATION=y to look for build errors, though. [ tglx: Removed SMP and !PARAVIRT dependencies as they not longer exist ] Signed-off-by: Dave Hansen <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Rik van Riel <[email protected]> Cc: [email protected] Cc: Denys Vlasenko <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Peter Zijlstra <[email protected]> Cc: Brian Gerst <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Borislav Petkov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: [email protected] Cc: Linus Torvalds <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] --- security/Kconfig | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/security/Kconfig +++ b/security/Kconfig @@ -54,6 +54,16 @@ config SECURITY_NETWORK implement socket and networking access controls. If you are unsure how to answer this question, answer N. +config KERNEL_PAGE_TABLE_ISOLATION + bool "Remove the kernel mapping in user mode" + depends on X86_64 && JUMP_LABEL + help + This feature reduces the number of hardware side channels by + ensuring that the majority of kernel addresses are not mapped + into userspace. + + See Documentation/x86/pagetable-isolation.txt for more details. + config SECURITY_INFINIBAND bool "Infiniband Security Hooks" depends on SECURITY && INFINIBAND
