On Wed, 2017-08-16 at 16:01 +1000, Benjamin Herrenschmidt wrote:
> VSX uses a combination of the old vector registers, the old FP registers
> and new "second halves" of the FP registers.
>
> Thus when we need to see the VSX state in the thread struct
> (flush_vsx_to_thread) or when we'll use the VSX in the kernel
> (enable_kernel_vsx) we need to ensure they are all flushed into
> the thread struct if either of them is individually enabled.
>
> Unfortunately we only tested if the whole VSX was enabled, not
> if they were individually enabled.
>
> Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
And CC stable.
> ---
> arch/powerpc/kernel/process.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 9f3e2c932dcc..883216b4296a 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -362,7 +362,8 @@ void enable_kernel_vsx(void)
>
> cpumsr = msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
>
> - if (current->thread.regs && (current->thread.regs->msr & MSR_VSX)) {
> + if (current->thread.regs &&
> + (current->thread.regs->msr & (MSR_VSX|MSR_VEC|MSR_FP))) {
> check_if_tm_restore_required(current);
> /*
> * If a thread has already been reclaimed then the
> @@ -386,7 +387,7 @@ void flush_vsx_to_thread(struct task_struct *tsk)
> {
> if (tsk->thread.regs) {
> preempt_disable();
> - if (tsk->thread.regs->msr & MSR_VSX) {
> + if (tsk->thread.regs->msr & (MSR_VSX|MSR_VEC|MSR_FP)) {
> BUG_ON(tsk != current);
> giveup_vsx(tsk);
> }
