From: Josh Poimboeuf jpoimboe@kernel.org
commit 56aa4d221f1ee2c3a49b45b800778ec6e0ab73c5 upstream.
If the SMT state changes, SSBD might get accidentally disabled. Fix that.
Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Borislav Petkov bp@suse.de Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1335,7 +1335,8 @@ static void __init spectre_v2_select_mit
static void update_stibp_msr(void * __unused) { - write_spec_ctrl_current(x86_spec_ctrl_base, true); + u64 val = spec_ctrl_current() | (x86_spec_ctrl_base & SPEC_CTRL_STIBP); + write_spec_ctrl_current(val, true); }
/* Update x86_spec_ctrl_base in case SMT state changed. */