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    Subject[PATCH 24/30] KVM: x86: hyper-v: Honor HV_DEBUGGING privilege bit
    Date
    Hyper-V partition must possess 'HV_DEBUGGING' privilege to issue
    HVCALL_POST_DEBUG_DATA/HVCALL_RETRIEVE_DEBUG_DATA/
    HVCALL_RESET_DEBUG_SESSION hypercalls.

    Note, when SynDBG is disabled hv_check_hypercall_access() returns
    'true' (like for any other unknown hypercall) so the result will
    be HV_STATUS_INVALID_HYPERCALL_CODE and not HV_STATUS_ACCESS_DENIED.

    Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
    ---
    arch/x86/kvm/hyperv.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
    index 523f63287636..36ec688cda4e 100644
    --- a/arch/x86/kvm/hyperv.c
    +++ b/arch/x86/kvm/hyperv.c
    @@ -2035,6 +2035,15 @@ static bool hv_check_hypercall_access(struct kvm_vcpu_hv *hv_vcpu, u16 code)
    return hv_vcpu->cpuid_cache.features_ebx & HV_POST_MESSAGES;
    case HVCALL_SIGNAL_EVENT:
    return hv_vcpu->cpuid_cache.features_ebx & HV_SIGNAL_EVENTS;
    + case HVCALL_POST_DEBUG_DATA:
    + case HVCALL_RETRIEVE_DEBUG_DATA:
    + case HVCALL_RESET_DEBUG_SESSION:
    + /*
    + * Return 'true' when SynDBG is disabled so the resulting code
    + * will be HV_STATUS_INVALID_HYPERCALL_CODE.
    + */
    + return !kvm_hv_is_syndbg_enabled(hv_vcpu->vcpu) ||
    + hv_vcpu->cpuid_cache.features_ebx & HV_DEBUGGING;
    default:
    break;
    }
    --
    2.30.2
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