Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754516Ab0FMPEm (ORCPT ); Sun, 13 Jun 2010 11:04:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11477 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752730Ab0FMPEP (ORCPT ); Sun, 13 Jun 2010 11:04:15 -0400 From: Avi Kivity To: Ingo Molnar , "H. Peter Anvin" Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/4] x86, fpu: Let the fpu remember which cpu it is active on Date: Sun, 13 Jun 2010 18:03:46 +0300 Message-Id: <1276441427-31514-4-git-send-email-avi@redhat.com> In-Reply-To: <1276441427-31514-1-git-send-email-avi@redhat.com> References: <1276441427-31514-1-git-send-email-avi@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6647 Lines: 254 Add a member fpu->cpu to struct fpu which contains which cpu has this fpu register set loaded (or -1 if the registers were flushed to memory in fpu->state). The various fpu accesors are modified to IPI the loaded cpu if it happens to be different from the current cpu. Signed-off-by: Avi Kivity --- arch/x86/include/asm/i387.h | 115 +++++++++++++++++++++++++++++++++++-- arch/x86/include/asm/processor.h | 4 + arch/x86/kernel/i387.c | 3 + arch/x86/kernel/process.c | 1 + 4 files changed, 116 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index df5badf..124c89d 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -174,7 +174,7 @@ static inline void fpu_fxsave(struct fpu *fpu) #endif } -static inline void fpu_save_init(struct fpu *fpu) +static inline void __fpu_save_init(struct fpu *fpu) { if (use_xsave()) fpu_xsave(fpu); @@ -222,10 +222,7 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx) #define safe_address (kstat_cpu(0).cpustat.user) #endif -/* - * These must be called with preempt disabled - */ -static inline void fpu_save_init(struct fpu *fpu) +static inline void __fpu_save_init(struct fpu *fpu) { if (use_xsave()) { struct xsave_struct *xstate = &fpu->state->xsave; @@ -273,6 +270,33 @@ end: #endif /* CONFIG_X86_64 */ +static inline bool fpu_loaded(struct fpu *fpu) +{ + return fpu->cpu == smp_processor_id(); +} + +static inline bool fpu_remote(struct fpu *fpu) +{ + return fpu->cpu != -1 && fpu->cpu != smp_processor_id(); +} + +/* + * These must be called with preempt disabled + */ +static inline void fpu_save_init(struct fpu *fpu) +{ + ulong flags; + + if (__get_cpu_var(current_fpu) != fpu + || fpu->cpu != smp_processor_id()) + return; + local_irq_save(flags); + __fpu_save_init(fpu); + fpu->cpu = -1; + __get_cpu_var(current_fpu) = NULL; + local_irq_restore(flags); +} + static inline void __save_init_fpu(struct task_struct *tsk) { fpu_save_init(&tsk->thread.fpu); @@ -284,7 +308,7 @@ static inline int fpu_fxrstor_checking(struct fpu *fpu) return fxrstor_checking(&fpu->state->fxsave); } -static inline int fpu_restore_checking(struct fpu *fpu) +static inline int __fpu_restore_checking(struct fpu *fpu) { if (use_xsave()) return fpu_xrstor_checking(fpu); @@ -292,6 +316,47 @@ static inline int fpu_restore_checking(struct fpu *fpu) return fpu_fxrstor_checking(fpu); } +static inline void __fpu_unload(void *_fpu) +{ + struct fpu *fpu = _fpu; + unsigned cr0 = read_cr0(); + + if (cr0 & X86_CR0_TS) + clts(); + if (__get_cpu_var(current_fpu) == fpu) + fpu_save_init(fpu); + if (cr0 & X86_CR0_TS) + write_cr0(cr0); +} + +static inline void fpu_unload(struct fpu *fpu) +{ + int cpu = ACCESS_ONCE(fpu->cpu); + + if (cpu != -1) + smp_call_function_single(cpu, __fpu_unload, fpu, 1); +} + +static inline int fpu_restore_checking(struct fpu *fpu) +{ + ulong flags; + struct fpu *oldfpu; + int ret; + + if (fpu->cpu == smp_processor_id()) + return 0; + fpu_unload(fpu); + local_irq_save(flags); + oldfpu = __get_cpu_var(current_fpu); + if (oldfpu) + fpu_save_init(oldfpu); + ret = __fpu_restore_checking(fpu); + fpu->cpu = smp_processor_id(); + __get_cpu_var(current_fpu) = fpu; + local_irq_restore(flags); + return ret; +} + static inline int restore_fpu_checking(struct task_struct *tsk) { return fpu_restore_checking(&tsk->thread.fpu); @@ -451,18 +516,46 @@ static bool fpu_allocated(struct fpu *fpu) return fpu->state != NULL; } +static inline void fpu_init_empty(struct fpu *fpu) +{ + fpu->state = NULL; + fpu->cpu = -1; +} + static inline int fpu_alloc(struct fpu *fpu) { if (fpu_allocated(fpu)) return 0; fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL); + fpu->cpu = -1; if (!fpu->state) return -ENOMEM; WARN_ON((unsigned long)fpu->state & 15); return 0; } -static inline void fpu_free(struct fpu *fpu) +static inline void __fpu_forget(void *_fpu) +{ + struct fpu *fpu = _fpu; + + if (fpu->cpu == smp_processor_id()) { + fpu->cpu = -1; + __get_cpu_var(current_fpu) = NULL; + } +} + +static inline void fpu_forget(struct fpu *fpu) +{ + int cpu; + + preempt_disable(); + cpu = ACCESS_ONCE(fpu->cpu); + if (cpu != -1) + smp_call_function_single(cpu, __fpu_forget, fpu, 1); + preempt_enable(); +} + +static inline void __fpu_free(struct fpu *fpu) { if (fpu->state) { kmem_cache_free(task_xstate_cachep, fpu->state); @@ -470,8 +563,16 @@ static inline void fpu_free(struct fpu *fpu) } } +static inline void fpu_free(struct fpu *fpu) +{ + fpu_forget(fpu); + __fpu_free(fpu); +} + static inline void fpu_copy(struct fpu *dst, struct fpu *src) { + fpu_unload(src); + fpu_unload(dst); memcpy(dst->state, src->state, xstate_size); } diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 7e5c6a6..98996fe 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -378,8 +378,11 @@ union thread_xstate { struct fpu { union thread_xstate *state; + int cpu; /* -1 = unloaded */ }; +DECLARE_PER_CPU(struct fpu *, current_fpu); + #ifdef CONFIG_X86_64 DECLARE_PER_CPU(struct orig_ist, orig_ist); @@ -892,6 +895,7 @@ static inline void spin_lock_prefetch(const void *x) .vm86_info = NULL, \ .sysenter_cs = __KERNEL_CS, \ .io_bitmap_ptr = NULL, \ + .fpu = { .cpu = -1, }, \ } /* diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index c4444bc..e56f486 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -38,6 +38,9 @@ # define HAVE_HWFP 1 #endif +DEFINE_PER_CPU(struct fpu *, current_fpu); +EXPORT_PER_CPU_SYMBOL_GPL(current_fpu); + static unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu; unsigned int xstate_size; unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32); diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index ebcfcce..16a7a9b 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -35,6 +35,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) int ret; *dst = *src; + fpu_init_empty(&dst->thread.fpu); if (fpu_allocated(&src->thread.fpu)) { memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu)); ret = fpu_alloc(&dst->thread.fpu); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/