[1/5] powerpc: Test MSR_FP and MSR_VEC when enabling/flushing VSX

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 <benh@kernel.crashing.org>
---
 arch/powerpc/kernel/process.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

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 <benh@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);
>  		}

On Wed, 2017-08-16 at 06:01:14 UTC, 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 <benh@kernel.crashing.org>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/5a69aec945d27e78abac9fd032533d

cheers