Method read_config_register

pci/src/vfio.rs:1353–1390

(&mut self, reg_idx: usize)

    }

    pub(crate) fn read_config_register(&mut self, reg_idx: usize) -> u32 {
        // When reading the BARs, we trap it and return what comes
        // from our local configuration space. We want the guest to
        // use that and not the VFIO device BARs as it does not map
        // with the guest address space.
        if (PCI_CONFIG_BAR0_INDEX..PCI_CONFIG_BAR0_INDEX + BAR_NUMS).contains(&reg_idx)
            || reg_idx == PCI_ROM_EXP_BAR_INDEX
        {
            return self.configuration.read_reg(reg_idx);
        }

        if let Some(id) = self.get_msix_cap_idx() {
            let msix = self.interrupt.msix.as_mut().unwrap();
            if reg_idx * 4 == id + 4 {
                return msix.cap.table;
            } else if reg_idx * 4 == id + 8 {
                return msix.cap.pba;
            }
        }

        // Since we don't support passing multi-functions devices, we should
        // mask the multi-function bit, bit 7 of the Header Type byte on the
        // register 3.
        let mask = if reg_idx == PCI_HEADER_TYPE_REG_INDEX {
            0xff7f_ffff
        } else {
            0xffff_ffff
        };

        // The config register read comes from the VFIO device itself.
        let mut value = self.vfio_wrapper.read_config_dword((reg_idx * 4) as u32) & mask;

        if let Some(config_patch) = self.patches.get(&reg_idx) {
            value = (value & !config_patch.mask) | config_patch.patch;
        }

        value
    }

    fn state(&self) -> VfioCommonState {
        let intx_state = self.interrupt.intx.as_ref().map(|intx| IntxState {