Re: [PATCH] target/arm: Correct calculation of tlb range invalidate length

[Richard Henderson]

On 11/30/21 6:32 PM, Peter Maydell wrote:
> 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
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/734
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Not marked for-6.2 because this isn't a regression: we
> shipped the TLBI range invalidate support in 6.1.
> I have no repro case for this issue, but this doesn't break
> booting an aarch64 kernel, at least.
> ---

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~