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KVM: s390: Fix potential crash in preemptible kernels

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There is a potential race for preemptible kernels, where
 the host kernel would get a fault when it is preempted as
 the wrong point in time.
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Merge tag 'kvm-s390-next-5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fix potential crash in preemptible kernels

There is a potential race for preemptible kernels, where
the host kernel would get a fault when it is preempted as
the wrong point in time.
This commit is contained in:
Paolo Bonzini 2021-04-17 08:29:41 -04:00
commit 387cb8e89d
1 changed files with 2 additions and 2 deletions
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4
arch/s390/kvm/kvm-s390.c
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@ -4313,16 +4313,16 @@ static void store_regs_fmt2(struct kvm_vcpu *vcpu)
kvm_run->s.regs.bpbc = (vcpu->arch.sie_block->fpf & FPF_BPBC) == FPF_BPBC;
kvm_run->s.regs.diag318 = vcpu->arch.diag318_info.val;
if (MACHINE_HAS_GS) {
preempt_disable();
__ctl_set_bit(2, 4);
if (vcpu->arch.gs_enabled)
save_gs_cb(current->thread.gs_cb);
preempt_disable();
current->thread.gs_cb = vcpu->arch.host_gscb;
restore_gs_cb(vcpu->arch.host_gscb);
preempt_enable();
if (!vcpu->arch.host_gscb)
__ctl_clear_bit(2, 4);
vcpu->arch.host_gscb = NULL;
preempt_enable();
}
/* SIE will save etoken directly into SDNX and therefore kvm_run */
}