target/arm: Correct calculation of tlb range invalidate length

target/arm: Correct calculation of tlb range invalidate length

The calculation of the length of TLB range invalidate operations
in tlbi_aa64_range_get_length() is incorrect in two ways:
 * the NUM field is 5 bits, but we read only 4 bits
 * we miscalculate the page_shift value, because of an
   off-by-one error:
    TG 0b00 is invalid
    TG 0b01 is 4K granule size == 4096 == 2^12
    TG 0b10 is 16K granule size == 16384 == 2^14
    TG 0b11 is 64K granule size == 65536 == 2^16
   so page_shift should be (TG - 1) * 2 + 12

Thanks to the bug report submitter Cha HyunSoo for identifying
both these errors.

Fixes: 84940ed82552d3c ("target/arm: Add support for FEAT_TLBIRANGE")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/734
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20211130173257.1274194-1-peter.maydell@linaro.org