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    Subject[PATCH 3.13 103/187] KVM: PPC: Book3S PR: Take SRCU read lock around RTAS kvm_read_guest() call
    Date
    3.13.11.7 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Paul Mackerras <paulus@samba.org>

    commit ef1af2e29622ff3403926ae801a2b10da075a2de upstream.

    This does for PR KVM what c9438092cae4 ("KVM: PPC: Book3S HV: Take SRCU
    read lock around kvm_read_guest() call") did for HV KVM, that is,
    eliminate a "suspicious rcu_dereference_check() usage!" warning by
    taking the SRCU lock around the call to kvmppc_rtas_hcall().

    It also fixes a return of RESUME_HOST to return EMULATE_FAIL instead,
    since kvmppc_h_pr() is supposed to return EMULATE_* values.

    Signed-off-by: Paul Mackerras <paulus@samba.org>
    Signed-off-by: Alexander Graf <agraf@suse.de>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    arch/powerpc/kvm/book3s_pr_papr.c | 9 +++++++--
    1 file changed, 7 insertions(+), 2 deletions(-)

    diff --git a/arch/powerpc/kvm/book3s_pr_papr.c b/arch/powerpc/kvm/book3s_pr_papr.c
    index 5efa97b..7a801b5 100644
    --- a/arch/powerpc/kvm/book3s_pr_papr.c
    +++ b/arch/powerpc/kvm/book3s_pr_papr.c
    @@ -258,6 +258,8 @@ static int kvmppc_h_pr_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd)

    int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
    {
    + int rc, idx;
    +
    switch (cmd) {
    case H_ENTER:
    return kvmppc_h_pr_enter(vcpu);
    @@ -286,8 +288,11 @@ int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
    break;
    case H_RTAS:
    if (list_empty(&vcpu->kvm->arch.rtas_tokens))
    - return RESUME_HOST;
    - if (kvmppc_rtas_hcall(vcpu))
    + break;
    + idx = srcu_read_lock(&vcpu->kvm->srcu);
    + rc = kvmppc_rtas_hcall(vcpu);
    + srcu_read_unlock(&vcpu->kvm->srcu, idx);
    + if (rc)
    break;
    kvmppc_set_gpr(vcpu, 3, 0);
    return EMULATE_DONE;
    --
    1.9.1


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