Method detect_bar_reprogramming

pci/src/configuration.rs:972–1087

(
        &mut self,
        reg_idx: usize,
        data: &[u8],
    )

    }

    fn detect_bar_reprogramming(
        &mut self,
        reg_idx: usize,
        data: &[u8],
    ) -> Option<BarReprogrammingParams> {
        if data.len() != 4 {
            return None;
        }

        let value = LittleEndian::read_u32(data);

        let mask = self.writable_bits[reg_idx];
        if (BAR0_REG..BAR0_REG + NUM_BAR_REGS).contains(&reg_idx) {
            // Ignore the case where the BAR size is being asked for.
            if value == 0xffff_ffff {
                return None;
            }

            let bar_idx = reg_idx - BAR0_REG;
            // Handle special case where the address being written is
            // different from the address initially provided. This is a
            // BAR reprogramming case which needs to be properly caught.
            if let Some(bar_type) = self.bars[bar_idx].r#type {
                // In case of 64 bits memory BAR, we don't do anything until
                // the upper BAR is modified, otherwise we would be moving the
                // BAR to a wrong location in memory.
                if bar_type == PciBarRegionType::Memory64BitRegion {
                    return None;
                }

                // Ignore the case where the value is unchanged.
                if (value & mask) == (self.bars[bar_idx].addr & mask) {
                    return None;
                }

                info!(
                    "Detected BAR reprogramming: (BAR {}) 0x{:x}->0x{:x}",
                    bar_idx, self.bars[bar_idx].addr, value
                );
                let old_base = u64::from(self.bars[bar_idx].addr & mask);
                let new_base = u64::from(value & mask);
                let len = u64::from(
                    decode_32_bits_bar_size(self.bars[bar_idx].size)
                        .ok_or(Error::Decode32BarSize)
                        .unwrap(),
                );
                let region_type = bar_type;

                self.bars[bar_idx].addr = value;

                return Some(BarReprogrammingParams {
                    old_base,
                    new_base,
                    len,
                    region_type,
                });
            } else if (bar_idx > 0)
                && ((self.registers[reg_idx - 1] & self.writable_bits[reg_idx - 1])