Re: [Qemu-devel] [PATCH 08/16] translate-all: work page-by-page in tb_invalidate_phys_range_1
Emilio G. Cota 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
Reviewed-by: Alex Bennée
> ---
> 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
Re: [Qemu-devel] [PATCH 08/16] translate-all: work page-by-page in tb_invalidate_phys_range_1
Emilio G. Cota 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
Reviewed-by: Alex Bennée
> ---
> 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
Re: [Qemu-devel] [PATCH 08/16] translate-all: work page-by-page in tb_invalidate_phys_range_1
On 02/26/2018 09:39 PM, Emilio G. Cota wrote: > 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 > --- Reviewed-by: Richard Henderson r~
[Qemu-devel] [PATCH 08/16] translate-all: work page-by-page in tb_invalidate_phys_range_1
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
---
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);
}
}
--
2.7.4
