KVM: Initialize fpu state in preemptible context (e5c30142) · Commits · 戴 / test

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>

arch/x86/kernel/i387.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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,

arch/x86/kvm/x86.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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);

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