  Two families of models are currently considered to describe an accretion flow
onto black holes and production of the observed X-ray radiation: (1) a standard
cold accretion disk with a hot corona above it and (2) an outer truncated
accretion disk with a hot semispherical inner flow. We compute spectra in the
scenario with a hot inner flow surrounded by a truncated accretion disk covered
by a hot corona and test the results on a sample of high redshift (z > 4)
quasars observed with Chandra. We find that in order to reproduce the ratio of
optical to X-ray fluxes (the $\alpha_{\rm ox}$ parameter), the optical depth of
the Comptonizing plasma has to be rather low ($\tau = 0.02 - 0.15 in the corona
above the disk, and $\tau = 0.15 - 0.70 in the hot inner flow). This, together
with the observed X-ray photon indices, implies either a high temperature in a
thermal plasma ($kT_{\rm e} = 90 - 500 keV), or a nonthermal electron
distribution in the plasma. We put an upper limit on the disk truncation
radius, $r_{\rm tr} \leq 40 R_{\rm S}$. The modeled accretion rate is high,
$\dot{m} > 0.2 Eddington rate, which may suggest that high-z radio quiet
quasars are analogs of X-ray binaries in their high or very high state.
