From 20041a0ebf3f9d99db3a8ffd81a679b925cb9fe4 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 18 Feb 2019 23:42:51 +0100 Subject: x86/speculation/mds: Clear CPU buffers on exit to user commit 04dcbdb8057827b043b3c71aa397c4c63e67d086 upstream. Add a static key which controls the invocation of the CPU buffer clear mechanism on exit to user space and add the call into prepare_exit_to_usermode() and do_nmi() right before actually returning. Add documentation which kernel to user space transition this covers and explain why some corner cases are not mitigated. Signed-off-by: Thomas Gleixner Reviewed-by: Greg Kroah-Hartman Reviewed-by: Borislav Petkov Reviewed-by: Frederic Weisbecker Reviewed-by: Jon Masters Tested-by: Jon Masters Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/common.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/x86/entry/common.c') diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index b0cd306dc527..8841d016b4a4 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -28,6 +28,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -206,6 +207,8 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) #endif user_enter_irqoff(); + + mds_user_clear_cpu_buffers(); } #define SYSCALL_EXIT_WORK_FLAGS \ -- cgit v1.2.3