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Re: [Qemu-devel] [PATCH 08/16] translate-all: work page-by-page in tb_in
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH 08/16] translate-all: work page-by-page in tb_invalidate_phys_range_1 |
Date: |
Thu, 29 Mar 2018 11:17:27 +0100 |
User-agent: |
mu4e 1.1.0; emacs 26.0.91 |
Emilio G. Cota <address@hidden> writes:
> So that we pass a same-page range to tb_invalidate_phys_page_range,
> instead of always passing an end address that could be on a different
> page.
>
> As discussed with Peter Maydell on the list [1], tb_invalidate_phys_page_range
> doesn't actually do much with 'end', which explains why we have never
> hit a bug despite going against what the comment on top of
> tb_invalidate_phys_page_range requires:
>
>> * Invalidate all TBs which intersect with the target physical address range
>> * [start;end[. NOTE: start and end must refer to the *same* physical page.
>
> The appended honours the comment, which avoids confusion.
>
> While at it, rework the loop into a for loop, which is less error prone
> (e.g. "continue" won't result in an infinite loop).
>
> [1] https://lists.gnu.org/archive/html/qemu-devel/2017-07/msg09165.html
>
> Signed-off-by: Emilio G. Cota <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
> ---
> accel/tcg/translate-all.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index 816419a..a98e182 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -1381,10 +1381,14 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
> */
> static void tb_invalidate_phys_range_1(tb_page_addr_t start, tb_page_addr_t
> end)
> {
> - while (start < end) {
> - tb_invalidate_phys_page_range(start, end, 0);
> - start &= TARGET_PAGE_MASK;
> - start += TARGET_PAGE_SIZE;
> + tb_page_addr_t next;
> +
> + for (next = (start & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
> + start < end;
> + start = next, next += TARGET_PAGE_SIZE) {
> + tb_page_addr_t bound = MIN(next, end);
> +
> + tb_invalidate_phys_page_range(start, bound, 0);
> }
> }
--
Alex Bennée