From: Mark Brown broonie@kernel.org
commit 714f3cbd70a4db9f9b7fe5b8a032896ed33fb824 upstream.
Currently as part of handling a SME access trap we flush the SVE register state. This is not needed and would corrupt register state if the task has access to the SVE registers already. For non-streaming mode accesses the required flushing will be done in the SVE access trap. For streaming mode SVE register accesses the architecture guarantees that the register state will be flushed when streaming mode is entered or exited so there is no need for us to do so. Simply remove the register initialisation.
Fixes: 8bd7f91c03d8 ("arm64/sme: Implement traps and syscall handling for SME") Signed-off-by: Mark Brown broonie@kernel.org Reviewed-by: Catalin Marinas catalin.marinas@arm.com Link: https://lore.kernel.org/r/20220817182324.638214-5-broonie@kernel.org Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/fpsimd.c | 11 ----------- 1 file changed, 11 deletions(-)
--- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1463,17 +1463,6 @@ void do_sme_acc(unsigned long esr, struc fpsimd_bind_task_to_cpu(); }
- /* - * If SVE was not already active initialise the SVE registers, - * any non-shared state between the streaming and regular SVE - * registers is architecturally guaranteed to be zeroed when - * we enter streaming mode. We do not need to initialize ZA - * since ZA must be disabled at this point and enabling ZA is - * architecturally defined to zero ZA. - */ - if (system_supports_sve() && !test_thread_flag(TIF_SVE)) - sve_init_regs(); - put_cpu_fpsimd_context(); }