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| author | Thomas Gleixner <tglx@linutronix.de> | 2019-02-18 23:42:51 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-03-06 21:52:13 +0100 |
| commit | 04dcbdb8057827b043b3c71aa397c4c63e67d086 (patch) | |
| tree | ef837807f05eaf4ce6abe5d62b5ef5703931c3e5 /arch/x86/kernel/nmi.c | |
| parent | x86/speculation/mds: Add mds_clear_cpu_buffers() (diff) | |
| download | linux-04dcbdb8057827b043b3c71aa397c4c63e67d086.tar.xz linux-04dcbdb8057827b043b3c71aa397c4c63e67d086.zip | |
x86/speculation/mds: Clear CPU buffers on exit to user
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 <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Jon Masters <jcm@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>
Diffstat (limited to 'arch/x86/kernel/nmi.c')
| -rw-r--r-- | arch/x86/kernel/nmi.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 18bc9b51ac9b..086cf1d1d71d 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -34,6 +34,7 @@ #include <asm/x86_init.h> #include <asm/reboot.h> #include <asm/cache.h> +#include <asm/nospec-branch.h> #define CREATE_TRACE_POINTS #include <trace/events/nmi.h> @@ -533,6 +534,9 @@ nmi_restart: write_cr2(this_cpu_read(nmi_cr2)); if (this_cpu_dec_return(nmi_state)) goto nmi_restart; + + if (user_mode(regs)) + mds_user_clear_cpu_buffers(); } NOKPROBE_SYMBOL(do_nmi); |