KVM: PPC: Book3S HV: Read kvm->arch.emul_smt_mode under kvm->lock

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Commit 1e175d2 ("KVM: PPC: Book3S HV: Pack VCORE IDs to access full
VCPU ID space", 2018-07-25) added code that uses kvm->arch.emul_smt_mode
before any VCPUs are created.  However, userspace can change
kvm->arch.emul_smt_mode at any time up until the first VCPU is created.
Hence it is (theoretically) possible for the check in
kvmppc_core_vcpu_create_hv() to race with another userspace thread
changing kvm->arch.emul_smt_mode.

This fixes it by moving the test that uses kvm->arch.emul_smt_mode into
the block where kvm->lock is held.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

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Paul Mackerras 2018-07-26 15:38:41 +10:00

parent 1ebe6b81eb

commit b5c6f7607b

1 changed files with 8 additions and 9 deletions

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arch/powerpc/kvm/book3s_hv.c

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