diff options
| -rw-r--r-- | arch/x86/include/asm/i387.h | 28 | ||||
| -rw-r--r-- | arch/x86/kernel/i387.c | 13 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx.c | 10 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 4 |
4 files changed, 40 insertions, 15 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index 6c3bd378281..ed8089d6909 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -24,8 +24,32 @@ extern int dump_fpu(struct pt_regs *, struct user_i387_struct *); extern void math_state_restore(void); extern bool irq_fpu_usable(void); -extern void kernel_fpu_begin(void); -extern void kernel_fpu_end(void); + +/* + * Careful: __kernel_fpu_begin/end() must be called with preempt disabled + * and they don't touch the preempt state on their own. + * If you enable preemption after __kernel_fpu_begin(), preempt notifier + * should call the __kernel_fpu_end() to prevent the kernel/user FPU + * state from getting corrupted. KVM for example uses this model. + * + * All other cases use kernel_fpu_begin/end() which disable preemption + * during kernel FPU usage. + */ +extern void __kernel_fpu_begin(void); +extern void __kernel_fpu_end(void); + +static inline void kernel_fpu_begin(void) +{ + WARN_ON_ONCE(!irq_fpu_usable()); + preempt_disable(); + __kernel_fpu_begin(); +} + +static inline void kernel_fpu_end(void) +{ + __kernel_fpu_end(); + preempt_enable(); +} /* * Some instructions like VIA's padlock instructions generate a spurious diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index 6782e398386..675a0501244 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -73,32 +73,29 @@ bool irq_fpu_usable(void) } EXPORT_SYMBOL(irq_fpu_usable); -void kernel_fpu_begin(void) +void __kernel_fpu_begin(void) { struct task_struct *me = current; - WARN_ON_ONCE(!irq_fpu_usable()); - preempt_disable(); if (__thread_has_fpu(me)) { __save_init_fpu(me); __thread_clear_has_fpu(me); - /* We do 'stts()' in kernel_fpu_end() */ + /* We do 'stts()' in __kernel_fpu_end() */ } else if (!use_eager_fpu()) { this_cpu_write(fpu_owner_task, NULL); clts(); } } -EXPORT_SYMBOL(kernel_fpu_begin); +EXPORT_SYMBOL(__kernel_fpu_begin); -void kernel_fpu_end(void) +void __kernel_fpu_end(void) { if (use_eager_fpu()) math_state_restore(); else stts(); - preempt_enable(); } -EXPORT_SYMBOL(kernel_fpu_end); +EXPORT_SYMBOL(__kernel_fpu_end); void unlazy_fpu(struct task_struct *tsk) { diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index c00f03de1b7..70dfcec3c46 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1493,8 +1493,12 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx) #ifdef CONFIG_X86_64 wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base); #endif - if (user_has_fpu()) - clts(); + /* + * If the FPU is not active (through the host task or + * the guest vcpu), then restore the cr0.TS bit. + */ + if (!user_has_fpu() && !vmx->vcpu.guest_fpu_loaded) + stts(); load_gdt(&__get_cpu_var(host_gdt)); } @@ -3730,7 +3734,7 @@ static void vmx_set_constant_host_state(void) unsigned long tmpl; struct desc_ptr dt; - vmcs_writel(HOST_CR0, read_cr0() | X86_CR0_TS); /* 22.2.3 */ + vmcs_writel(HOST_CR0, read_cr0() & ~X86_CR0_TS); /* 22.2.3 */ vmcs_writel(HOST_CR4, read_cr4()); /* 22.2.3, 22.2.5 */ vmcs_writel(HOST_CR3, read_cr3()); /* 22.2.3 FIXME: shadow tables */ diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index cf637f572bd..02b2cd52069 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5972,7 +5972,7 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) */ kvm_put_guest_xcr0(vcpu); vcpu->guest_fpu_loaded = 1; - kernel_fpu_begin(); + __kernel_fpu_begin(); fpu_restore_checking(&vcpu->arch.guest_fpu); trace_kvm_fpu(1); } @@ -5986,7 +5986,7 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) vcpu->guest_fpu_loaded = 0; fpu_save_init(&vcpu->arch.guest_fpu); - kernel_fpu_end(); + __kernel_fpu_end(); ++vcpu->stat.fpu_reload; kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); trace_kvm_fpu(0); |