[v1] accel/tcg: Convert victim tlb to IntervalTree

[PATCH 06/23] accel/tcg: Early exit for zero length in tlb_flush_range_by_mmuidx*

Posted by Richard Henderson 1 month, 2 weeks ago

Probably never happens, but next patches will assume non-zero length.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/cputlb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index fd8da8586f..93b42d18ee 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -801,6 +801,9 @@ void tlb_flush_range_by_mmuidx(CPUState *cpu, vaddr addr,
      * If all bits are significant, and len is small,
      * this devolves to tlb_flush_page.
      */
+    if (len == 0) {
+        return;
+    }
     if (bits >= TARGET_LONG_BITS && len <= TARGET_PAGE_SIZE) {
         tlb_flush_page_by_mmuidx(cpu, addr, idxmap);
         return;
@@ -839,6 +842,9 @@ void tlb_flush_range_by_mmuidx_all_cpus_synced(CPUState *src_cpu,
      * If all bits are significant, and len is small,
      * this devolves to tlb_flush_page.
      */
+    if (len == 0) {
+        return;
+    }
     if (bits >= TARGET_LONG_BITS && len <= TARGET_PAGE_SIZE) {
         tlb_flush_page_by_mmuidx_all_cpus_synced(src_cpu, addr, idxmap);
         return;
-- 
2.43.0

Re: [PATCH 06/23] accel/tcg: Early exit for zero length in tlb_flush_range_by_mmuidx*

Posted by Pierrick Bouvier 1 month, 2 weeks ago

On 10/9/24 08:08, Richard Henderson wrote:
> Probably never happens, but next patches will assume non-zero length.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   accel/tcg/cputlb.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index fd8da8586f..93b42d18ee 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -801,6 +801,9 @@ void tlb_flush_range_by_mmuidx(CPUState *cpu, vaddr addr,
>        * If all bits are significant, and len is small,
>        * this devolves to tlb_flush_page.
>        */
> +    if (len == 0) {
> +        return;
> +    }
>       if (bits >= TARGET_LONG_BITS && len <= TARGET_PAGE_SIZE) {
>           tlb_flush_page_by_mmuidx(cpu, addr, idxmap);
>           return;
> @@ -839,6 +842,9 @@ void tlb_flush_range_by_mmuidx_all_cpus_synced(CPUState *src_cpu,
>        * If all bits are significant, and len is small,
>        * this devolves to tlb_flush_page.
>        */
> +    if (len == 0) {
> +        return;
> +    }
>       if (bits >= TARGET_LONG_BITS && len <= TARGET_PAGE_SIZE) {
>           tlb_flush_page_by_mmuidx_all_cpus_synced(src_cpu, addr, idxmap);
>           return;

If this "probably never happens", wouldn't that be better to assert that 
len is strictly positive?

Re: [PATCH 06/23] accel/tcg: Early exit for zero length in tlb_flush_range_by_mmuidx*

Posted by Philippe Mathieu-Daudé 1 month, 2 weeks ago

On 9/10/24 12:08, Richard Henderson wrote:
> Probably never happens, but next patches will assume non-zero length.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   accel/tcg/cputlb.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index fd8da8586f..93b42d18ee 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -801,6 +801,9 @@ void tlb_flush_range_by_mmuidx(CPUState *cpu, vaddr addr,
>        * If all bits are significant, and len is small,
>        * this devolves to tlb_flush_page.
>        */
> +    if (len == 0) {
> +        return;
> +    }

Maybe clearer to move the check before the comment, otherwise:

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

>       if (bits >= TARGET_LONG_BITS && len <= TARGET_PAGE_SIZE) {
>           tlb_flush_page_by_mmuidx(cpu, addr, idxmap);
>           return;
> @@ -839,6 +842,9 @@ void tlb_flush_range_by_mmuidx_all_cpus_synced(CPUState *src_cpu,
>        * If all bits are significant, and len is small,
>        * this devolves to tlb_flush_page.
>        */
> +    if (len == 0) {
> +        return;
> +    }
>       if (bits >= TARGET_LONG_BITS && len <= TARGET_PAGE_SIZE) {
>           tlb_flush_page_by_mmuidx_all_cpus_synced(src_cpu, addr, idxmap);
>           return;