Create a single function that gives everything up (FP, VMX, VSX, SPE). Doing this all at once means we only do one MSR write.
A context switch microbenchmark using yield(): http://ozlabs.org/~anton/junkcode/context_switch2.c ./context_switch2 --test=yield --fp --altivec --vector 0 0 shows an improvement of 3% on POWER8. Signed-off-by: Anton Blanchard <an...@samba.org> --- arch/powerpc/include/asm/switch_to.h | 1 + arch/powerpc/kernel/process.c | 75 ++++++++++++++++++++++++++++-------- arch/powerpc/kvm/book3s_pr.c | 17 +------- 3 files changed, 63 insertions(+), 30 deletions(-) diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h index 9414dcb..8f85678 100644 --- a/arch/powerpc/include/asm/switch_to.h +++ b/arch/powerpc/include/asm/switch_to.h @@ -26,6 +26,7 @@ extern void __giveup_vsx(struct task_struct *); extern void giveup_vsx(struct task_struct *); extern void enable_kernel_spe(void); extern void load_up_spe(struct task_struct *); +extern void giveup_all(struct task_struct *); extern void switch_booke_debug_regs(struct debug_reg *new_debug); #ifdef CONFIG_PPC_FPU diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 9f8444b..a1540ee 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -308,6 +308,64 @@ void flush_spe_to_thread(struct task_struct *tsk) } #endif /* CONFIG_SPE */ +static unsigned long msr_all_available; + +static int __init init_msr_all_available(void) +{ +#ifdef CONFIG_PPC_FPU + msr_all_available |= MSR_FP; +#endif +#ifdef CONFIG_ALTIVEC + if (cpu_has_feature(CPU_FTR_ALTIVEC)) + msr_all_available |= MSR_VEC; +#endif +#ifdef CONFIG_VSX + if (cpu_has_feature(CPU_FTR_VSX)) + msr_all_available |= MSR_VSX; +#endif +#ifdef CONFIG_SPE + if (cpu_has_feature(CPU_FTR_SPE)) + msr_all_available |= MSR_SPE; +#endif + + return 0; +} +early_initcall(init_msr_all_available); + +void giveup_all(struct task_struct *tsk) +{ + unsigned long usermsr; + + if (!tsk->thread.regs) + return; + + usermsr = tsk->thread.regs->msr; + + if ((usermsr & msr_all_available) == 0) + return; + + msr_check_and_set(msr_all_available); + +#ifdef CONFIG_PPC_FPU + if (usermsr & MSR_FP) + __giveup_fpu(tsk); +#endif +#ifdef CONFIG_ALTIVEC + if (usermsr & MSR_VEC) + __giveup_altivec(tsk); +#endif +#ifdef CONFIG_VSX + if (usermsr & MSR_VSX) + __giveup_vsx(tsk); +#endif +#ifdef CONFIG_SPE + if (usermsr & MSR_SPE) + __giveup_spe(tsk); +#endif + + msr_check_and_clear(msr_all_available); +} + #ifdef CONFIG_PPC_ADV_DEBUG_REGS void do_send_trap(struct pt_regs *regs, unsigned long address, unsigned long error_code, int signal_code, int breakpt) @@ -839,21 +897,8 @@ struct task_struct *__switch_to(struct task_struct *prev, __switch_to_tm(prev); - if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP)) - giveup_fpu(prev); -#ifdef CONFIG_ALTIVEC - if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC)) - giveup_altivec(prev); -#endif /* CONFIG_ALTIVEC */ -#ifdef CONFIG_VSX - if (prev->thread.regs && (prev->thread.regs->msr & MSR_VSX)) - /* VMX and FPU registers are already save here */ - __giveup_vsx(prev); -#endif /* CONFIG_VSX */ -#ifdef CONFIG_SPE - if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE))) - giveup_spe(prev); -#endif /* CONFIG_SPE */ + /* Save FPU, Altivec, VSX and SPE state */ + giveup_all(prev); #ifdef CONFIG_PPC_ADV_DEBUG_REGS switch_booke_debug_regs(&new->thread.debug); diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 49f5dad..a78e0e6 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -1490,21 +1490,8 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) goto out; /* interrupts now hard-disabled */ - /* Save FPU state in thread_struct */ - if (current->thread.regs->msr & MSR_FP) - giveup_fpu(current); - -#ifdef CONFIG_ALTIVEC - /* Save Altivec state in thread_struct */ - if (current->thread.regs->msr & MSR_VEC) - giveup_altivec(current); -#endif - -#ifdef CONFIG_VSX - /* Save VSX state in thread_struct */ - if (current->thread.regs->msr & MSR_VSX) - __giveup_vsx(current); -#endif + /* Save FPU, Altivec and VSX state */ + giveup_all(current); /* Preload FPU if it's enabled */ if (kvmppc_get_msr(vcpu) & MSR_FP) -- 2.5.0 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
