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KVM: Initialize fpu state in preemptible context 

init_fpu() (which is indirectly called by the fpu switching code) assumes
it is in process context.  Rather than makeing init_fpu() use an atomic
allocation, which can cause a task to be killed, make sure the fpu is
already initialized when we enter the run loop.

KVM-Stable-Tag.
Reported-and-tested-by: Kirill A. Shutemov <kas@openvz.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2011-01-11 12:15:54 +02:00
parent 444e863d13
commit e5c3014282
2 changed files with 4 additions and 0 deletions
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1
arch/x86/kernel/i387.c
View File

@ -169,6 +169,7 @@ int init_fpu(struct task_struct *tsk)
set_stopped_child_used_math(tsk);
return 0;
}
EXPORT_SYMBOL_GPL(init_fpu);
/*
* The xstateregs_active() routine is the same as the fpregs_active() routine,

3
arch/x86/kvm/x86.c
View File

@ -5376,6 +5376,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
int r;
sigset_t sigsaved;
if (!tsk_used_math(current) && init_fpu(current))
return -ENOMEM;
if (vcpu->sigset_active)
sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);